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The Best AR-15 Cartridges Right Now

by Joseph von Benedikt   |  December 9th, 2013 175

If worst comes to worst and you ever have to pick up your trusty M4 clone and go to protecting hearth and home, which carbine cartridge is most likely to save your life?

While this debate has raged through the decades, flaring with every significant improvement and/or change in firearms design and ricocheting off of every military contract and police department purchase—the subject has grown even more complex of late, due to the introduction of dedicated M4/AR-15 cartridges such as the 6.8 SPC, 6.5 Grendel and .300 Blackout.

Yes, I know: Many deserving carbine cartridges such as the 7.62x39mm want in. And sure, some of them will leave size-14 combat boot-prints all over the cartridges just listed. But much as I deplore the necessity, let’s confine this discussion to rounds in one arena: those appropriate for the M4/AR-15 family. Otherwise this article would turn into a book.

Trouble is, each popular carbine cartridge has significant strengths, especially in certain areas. What will work best really depends on you and your shooting abilities, your environment and lifestyle, and the probable demands those unique elements will place on your carbine.

Here’s a close look at the strengths and weaknesses of a handful of the best AR-15 cartridges available on today’s market. Only you can decide which is best, so be sure to vote for your favorite.

  • Dan

    If only the author did a little research he could have written better summaries about each cartridge! 300blk hits the hardest? How does this make sense? 300blk maxes out at around 1400ftlbs of energy out of a 16″ barrel where both the 6.8 and 6.5 can achieve 1800ftlbs! That’s over 25% more energy and both 6.8 and 6.5 have higher BC’s with supersonic loads so they will have more energy on target! Bottom line is 6.5G and 6.8spc are so close at their effective range it becomes a Chevy vs Ford debate. 300blk is the perfect replacement for a suppressed 9mm MP-5. 5.56 is still adequate for most roles your m4 will be used for with the exception of hunting deer sized game.

    • Ffatcat

      Dan,
      I completely agreed with you until the deer size game part. More deer have been taken with .22cal bullets than any other caliber. I fully understand that deer hunting with 22cal. is illegal in the majority of the U.S. I would also like to point out that the average human is about the same size or larger than deer sized game. This is all pointless, since I prefer the 6.5 and have the ability to reload for awhile.

      • Jeffe

        You can’t substantiate that 22 claim any more than someone else claiming that the majority of deer shot with a 22 were maimed but survived.

        • Ffatcat

          Actually the 22 claim can be substantiated. There are hundreds of books written by hunters of what they used. Plus old hunting records combined with new hunting records. Next cross reference calibers used and….bing! With a little research, verification is not that hard. The hard part would be verifying maimed deer. Poor placed shots can and do happen with any caliber. Poor tracking habits of some hunters lead to false assumptions about maiming, etc.

      • Mark Gamblin

        I don’t know which caliber has the most but I do know I hunt big Kentucky deer with an AR ,223 and a 70 gn projectile and it drops em like a hammer!!!

        • Tedward

          Some states like VA don’t allow hunting and wounding deer with the 22 platform, to small and fast, pass-thrus happen to often with body shots but if people took head shots it probably would be fine. But its the law, so the Grendel is a legal caliber and lots of performance. 223/556 is a fun rifle to shoot but has its limits as even the Grendel does, but the Grendel is just a Grendel and fun to shoot.

  • tyler

    I vote 223 purely for the availability. Although not really mentioned in this article, in a SHTF situation 223 will be the widely used and avail rifle ammunition. Good luck finding 300 and 6.8 without a gunshop.

    • Nicholas Feeley

      In a SHTF situation .223 *will* be the widely used and available rifle ammunition.
      But at the same time, you could just pick up a new upper, too, as those would *also* be obtained at the same location.
      Just sayin’.
      (My go-to AR is chambered in 7.62x39mm. And all I’d need is to pick up that 5.56 upper and I’d be able to use both of the most commonly-used ammo.)

    • john

      With several million 5.56s being owned which ammo do you think will sell out first?
      Just last fall you could find 5.56 or 9mm ammo anywhere.

      • john

        couldn’t find it any where.

  • pwrserge

    Meh… The 5.56×45 round can be tweaked with the right load to do anything a snowflake cartridge can. Will it do it as well as a specialist? No. But it can do everything well enough.

  • JMac

    6.5 “It’s the only cartridge that fits in a standard AR-15-size rifle (less the barrel and bolt),” Are you kidding me? That was the whole point in the design of the 300 BLK, use the same bolt carrier, bolt, and mags, just need a different barrel. This guy has no credibility.

    • DustyG223

      JMac, the point he’s making about standard AR-15-sized rifles appears in the latter part of the sentence you quoted, where he states, “while outperforming both the .223/5.56mm and .308/7.62mm in terms of less wind drift, flatter extreme-range trajectory and more energy.”

  • RockRiverFreak

    .458 Socom nuff said

    • Louis M.

      I agree

  • Christopher Wallace

    I have an FNAR .308, and love it. They were using the right round when they built the AR-10, but instead of exploring the tech to keep the round, they went to the lighter round

    • LilWolfy

      The Army Ordnance Corps actually screwed us over-both soldiers and hunters alike when they tried to cram M1906 .30 caliber performance into a smaller case and action.

      We would have been much better off with what the British had developed with the smaller Enfield cartridges, namely the .270 and 280 Enfields. The pressure and recoil penalties of the .308 require heavier, larger actions, generate more recoil, and are more difficult to train with to get proficient at actually hitting things. .30 bores are terribly inefficient at generating performance, so you need pressure to get them going.

  • SWOArms

    Oh, you mean caliber. Cartridges are composed of case, powder, primer and bullet. You’re whole “article” is about which calibers are relevant.

    • JvB

      On the contrary, “caliber” is typically used to indicate bore diameter. As in: “The .30-caliber family of cartridges.”

  • SWOArms

    Oh, you mean caliber. A cartridge is the specific primer, case, powder and bullet – like 9mm Winchester Whitebox or M855. Von Benedikt, an editor-in-chief, is attempting to discuss the merits of caliber. I now know which caliber you prefer, but which cartridges are the best? That’s what I came here for.

    • Doug Hutter

      No, he means cartridge. Caliber is defined as the diameter of the projectile or barrel bore. The .30 caliber “family” includes “cartridges” such as .300 Blackout, .308 Winchester, .30-30, .30-06, .300 Winchester Magnum, etc.

  • SaxMan

    Why not just buy an AR10 and shoot .308/7.62 and get something that will outperform all these cartridges? Sorry but shoe horning a cartridge into a rifle built for another cartridge doesn’t get me all warm and fuzzy.

    • Adaris

      I agree. While the AR-15 is a great rifle, there are times when you need much more firepower. So just buy an AR-10 .308 rather than trying to upgrade a smaller platform with incrementally larger calibers.

      • Louis M.

        Firepower??

    • Lee Larsen

      Yep, that’s the way I see it too.

    • Lee Larsen

      Yep, that’s the way I see it too.

    • Armor-Hyde

      Different situations call for different calibers. Plus factor in overall cost. MY HYDRA system allows changing to multiple calibers which will fit thru either the standard magwell. It’s nice to have that versatility without having to carry a complete other rifle. There’s definitely nothing wrong with the .308 for most applications, but the block busting capability of a .50 Beowulf or .458 Socom are simply instances even the venerable .308 can’t measure up to!

      • SaxMan

        True both the .50 Beowulf and .458 Socom will do more damage. But at what cost? And where are you going to pick them up. If I walked in to my LGS they would laugh at me. Plus the .50 requires modifying the magazine feed lips, and doing so makes it a .50 only magazine. The biggest limit is the pressure that the AR15 bolt will withstand. It makes the .50 ballistics similar to a .45-70. Certainly no slouch but not gonna reach out and touch someone long distance. The .458 is more promising. But it is still single stack.

        • Tedward

          Well now you touched on another AR-15 platform that I also like. Alexander Arms has both and they both perform. The Beowulf is a great round and ammo is plentiful if you just order on line and get it while you can. (Cabelas, Underwood Ammo, Midway USA) I have over 1,000 rounds and only shoot it once in a while so it will last. It’s not like buring thru the 223 ammo, shout 20 rounds and you and your freinds will talk about it for weeks. You don’t need to shoot 500 rounds. Also you can reload it and that makes it cheap. Satern Machine also makes a 12.7×42 that shoots the Beowulf ammo and Midway USA Sells them when is production. Also the Beowulf uses factory standard 223 straight metal mags. I have used them for quite a long time and the C-products or AR-Stoner 20 round mags work flawlessly. NO Modifying.
          And all this AR-10 talk, this is about the AR-15 platform, find the right place to spill the beans and yes the 308 is good but like a few have said, its bigger, uses more powder to load ammo, heavier, not just the rifle but the ammo and its an AR-10. AR-10, I vote 6.5 Creedmore.

    • Ilpadrino113

      Versatility is why. The only thing you need to do to switch to 300 blackout is swap out the barrel. For the cost of a barrel you can have an awesome hog/coyote gun. Plus standard 223 cartridges can be cut down and resized to load up the 300, simply use plentiful 308 bullets and your in business if you hand load. For less than 250$ and some time you shoot a completely different caliber for a completely different purpose.

    • Rob Joblin

      6.5 Grendel has better long range capabilities than .308. Handloads are still supersonic at 1200 yards and terminally effective.

      • SaxMan

        And where can you buy 6.5 Grendel? True it is a great round but performance is more than just what you can get the round to do if you tweak it just so…. you have to roll your own or pay $2.00 per round from the 1 or 2 companies that are making it. And those companies are ALWAYS sold out. Trust me I have a 6.5 upper and can’t shoot it. I can buy .308 almost anywhere, and it is a NATO round so there will always be military stuff around too.

        • Rob Joblin

          Hey Sax I have the Hornaday progressive press, so reloading is a breeze in my case. 6.5 isn’t real popular as far as bare bullets go so price is medium for the projectile (bullet only). I can get good bullets cheaper than .308′s because they are in demand. Your upper: I’m wanting a super accurate 20 or 24″. Which barrel did you buy? I am looking for a Satern barrel: already have Vltor upper, handguard and incidentals…

          • Rob Joblin

            Is your upper for sale?

          • SaxMan

            I bought an Alexander Arms complete upper with a 24 Inch from Midway. It still has the original 1:9 twist barrel that came on the upper. It is pretty accurate. It was meant to be on a Rock River Arms lower with a Geissele G2S trigger. I built this just for the 6.5 and then had a hard time getting stuff to load with so I threw a Stag Arms .223/5.56 on the lower and my son shoots it a lot now. I think I’ll keep it for when/if the materials for reloading get easier to find. I like the way it shoots.

            Where do you buy bullets (projectiles). They are hard to find where I am.

          • joe anthony

            how can i tell if i have the saturn barrel, i was told it was ,when i bought this gun , im now looking to sell it for a 50 bmg .i purchased it from a sgt in army, its only had 20 rds run thru it ,break in .. any info on saturn barrel would help.

        • mike gee

          SaxMan, different strokes for different folks. The 5.56 AR is good enough for HD/SD and the final fanstasy belief in world ending shtf!( a real shtf is hurricane katrina or an 8.0 earthquake on the west coast, where civil security breaks down for a few weeks)

          Anyway, just got my hands on an enterprise arms inch pattern civie FAL. I know its not as accurate as the AR 10 but like the M1A, theres a REASON the rest of the free world went for the FAL!

          I want my “battle rifle” to be just that, and my civie BCM upper’d/ LMT lowered M4 clone to be the,lightweight clone it is. IF I had to reach past legally DEFENSIBLE HD range it will be my bolt action 10FP for accuracy and my FAL for”combat”( can’t believe as urban civie shooter I’m even entertaining the words”combat” or long range) the AR 10s cost way too much when you can buy a sturdier FAL or a M1A…

        • LilWolfy

          There are over 30 factory loads for it, with Hornady’s offerings being the most popular. Selway Armory has been selling a crapload of the 123gr SST’s at $17.99 per box, you can find plenty of it at prices that beat .308 match ammo if you check gunbot.

          Alexander Arms and Precision Firearms have a wide selection of factory loadings, and you end up with Lapua brass afterwards, which is highly valued even if you don’t reload. You normally can recover 65%-85% of your total ammo costs just be re-selling the once-fired Lapua brass.

      • Charles in Charge

        Much rather convert an AR-10 to .260 Rem instead of trying to cram a 6.5 into a shorter action

        • LilWolfy

          I have both. The .260 Rem spends a lot of time at home. Affordable, readily available factory ammunition plays a huge part in that, as does the fact that 6.5 Grendel is easier to pack up and go with. Rifle weight is drastically different in my case, and they are both supersonic for me well past 1000yds.

      • Craig Black

        I’m a Grendel owner with 3 in the house but sorry the Grendel does not have better long range ballistics. Thats just completely cool aid drinking silliness.

        • Rob Joblin

          Well believe what you like. You can Google for information if you are interested in more than just your opinion. Be sure to check long-range competition reviews while you are at it.

          • DaveS

            Great things, those internet searches. Not only do they back your position, Rob, but they also turn up Mr. Black as someone who is no stranger to contrary positions, in spite of overwhelming evidence against him.

          • Craig Black
          • Craig Black

            The Grendel is a sweet like caliber that is highly efficient and gets a lot of performance out of a little package but 308 performance it does not have.

        • LilWolfy

          If you run the comparison of even the 175gr SMK versus any of the 123gr 6.5mm target bullets, anyone can see that reality does not support your claims.

          And again, your reference to Jim Jones’ cult shows your level of debating skills. Demonize the opponent, associate them with crazy, lunatic fringe, drug consuming cult in the jungles who mass murdered infants, women, children, and men.

          The reality is that the Grendel provides real performance advantages within the AR15 that can be readily enjoyed by those who own it.

          Sounds like you have a personal vendetta.

          • PhillyBuster

            I saw the charts, as well, and came to similar conclusions. A short visit to his website quickly revealed that he really does have some kind of axe to grind, and explains the selection. Name calling and marginalization seems to be a favored tactic.

            Any honest analysis of the two cartridges supports the general conclusion that the Grendel not only can match the ballistics of the .308, it can exceed them with the appropriate loads.

            It’s a pity that some never outgrow the “My Dad can beat up Your Dad” phase.

          • GrendelFan99

            Craig Black is a rable rouser from way back. He was banned from the 65Grendel forum for his vendetta’s and misinformation.
            read the 65gredel forum about the liberty barrel (Satern) buy and the short throats and all the conflict and misinformation he spewed. He has an agenda against the Grendel. read the 65Grendel forum he is called xcountryrider there. or read his own blog mshunt

        • julio

          AR 15/ 6.5/16″/ 7.5 twist: 1/2″ at 100 yards 3 shoots, my best 1/4, 3 shoots at 100 yards. 120/123 gr hornady amax/sst. This Bullet is a Kick Asss.

      • Craig Black

        Rob put away the caliber coolaid. Heres a graph showing 6.5 Grendel using Hornady factory 123gr SST Vs factory 308 Nosler 150gr BT. http://www.shooterscalculator.com/ballistic-trajectory-chart.php?t=89ec1ba2

        • LilWolfy

          I looked at your comparison. You listed a 150gr NBT at 2875fps, compared to a 123gr at 2580fps. If you want to make a more unbiased comparison, run the 123gr SST at 2650fps, if 24″ gun velocity with hand loads was your goal, because you aren’t going to have a pleasant experience with hot factory ammunition in the .308 gas gun.

          Your 150gr NBT speed is the hottest load listed by Nosler for a 24″ bolt gun with N140. I spent years shooting .308 gas guns with 147gr, 150gr, 155gr, 167gr, 168gr, and 175gr, as well as hand-loading for it with Vihtavuori powders, among others. No way are you going to get a stable 2875fps speed with 150gr NBT from a .308 gasser in most cases. It will get there with a 24″ bolt gun no problem, but that speed is a bit optimistic with the gas-operated guns. 2820fps was really on the edge for me, as well as at least 6 other AR10 owners with 24″ and even 26″ barrels with a 155gr.

          You also have .308 recoil to contend with, which isn’t an issue with a heavy target gun, but definitely is with a lightweight hunting rifle.

          You use the colloquialism of “cool aid”, which is a reference to Jim Jones’ mass murder down in Guyana in 1978. That’s the definition of hyperbole. The 6.5 Grendel provides some very balanced performance options for those of us that like the AR15 and lightweight rifles, with negligible recoil that the .308 simply can’t deliver.

      • Deven Stoops

        Until the wind blows lol.

    • Lakan Kildap

      most AR-10′s of good quality are too heavy.

      • SaxMan

        8.61 LBS is too heavy? http://www.armalite.com/ItemForm.aspx?item=10TCBNF&ReturnUrl=Categories.aspx?Category=f4bd4a13-55d1-41aa-aea0-49488ec48776
        That is for an AR10TCBNF 1MOA rifle with a flat top receiver. Competition barrel and match trigger. I bet if you put a different handguard and butt stock on it you could get it sub 8 LBS

        Hell a stripped down Colt M4 is almost 7 (6.91). I’ll carry the extra 1 1/2 LBS any day for the added stopping power and range.

        But you can carry a lot more .556 pound for pound. That is why it is best to have both and not have to worry about switching uppers.

        • Lakan Kildap

          I should have said 7.62 AR. I get it, the AR-10 is an Armalite brand name. Most 7.62 AR-pattern rifles weigh more than 8.6. Some weigh more than 10 lbs. The new Smith is the only exception.

          The Armalite is fine, but it’s not the only choice. It’s often not the choice.

          • LilWolfy

            Actually, Eagle Arms started using the “Armalite” name back in the 1990′s. Their design is less like the original Hollywood Armalite AR10 of the 1950′s when compared to other AR10 variants on the market. The Knight’s SR25 was designed by Eugene Stoner and Reed Knight II, and is the most copied AR10 on the market, starting with DPMS’s LR-308 and AP4 series. It pre-dates the EA-10, and later “Armalte”-named AR10 that uses the modified M14 magazine.

            They all are “AR10′s”, or variants of Stoner’s original AR10, which is a completely different gun in terms of the receivers, BCG, fire control group, furniture, barrel, FSB, muzzle device, extension tube, buffer and recoil spring, sights, and charge handle.

        • julio

          AR 10 8.61 lb???…/ My is 6.5 creedmoor, 24″, SS, and weight 14.0 lb. Was your AR 10 made it from paper.

    • Justin Reid

      AR10 models that are truly trained hard with are very unreliable. There are a couple high end ones out that are good. The average ones are not designed to be truly put through their paces. The HK Mr7.62 I think it is, the LWRC REPR, and from the limited experience I have with it the SIG 716 are the only three I would rest my life on. Anything under $2,000 and I’m going with a Springfield M1A fitted with an EBR stock. That easy. I’ve seen way too many off the shelf AR10′s malfunction after a good number of rounds (500-1000) to trust them. I owned a DPMS and a Bushmaster and they didn’t hack it. Turned around and sold them. It’s funny because after I became a fan of James Yeager’s youtube channel, I find he feels exactly the same way. Without spending in excess of $2,500, it won’t work well enough to depend on.

      • SaxMan

        There is only ONE AR10 and they are made by Armalite. There may be other AR type rifles that fire .308/7.62 rounds but they are NOT AR10′s. I have easily 3000 rounds through my AR10 and it has been one of the most reliable AR type weapons in my stable. Like any rifle you need to look at the history and past issues. And I paid significantly less than $2500 for my AR10 ($1800 and some change before prices went crazy on AR’s). Others may say they are AR10′s but when I say AR10 I am referring to Armalite AR10 rifles. HK, DPMS, LWRC and SIG do not make AR10′s they make AR type rifles that are chambered in .308/7.62 and for the most parts have no interchangeable parts with each other or AR10′s.

        The AR10 has been in development since 1955 and was actually in development before the M-16. Like the M-16 it had some teething problems early on but those problems are way in the past. Check out the history of Armalite at http://www.armalite.com/images/Library%5CHistory.pdf

        • LilWolfy

          The Armalite companies you are talking about are two, totally different companies. One is the real one, the other is Eagle Arms re-branded.

          Would you consider a Dutch Armalite AR10 to be one of the only real ones? They were made under licensed contract from Fairchild/Armalite.

          This debate about which ones are the ONLY REAL ones is rather silly.

    • LilWolfy

      I’ve owned a bunch of AR10′s. The Grendel really put me in a position where I could no longer justify owning anything in .308 Winchester, especially in a light rifle. I’m at a point where I have zero desire to own anything with a .30 bore.

      The .222 Remington Special, aka 5.56×45, was shoe horned into the AR15. With the right components, assembly methods, and quality control, it can be done reliably and effectively.

      I have had nothing but reliable performance with the 6.5 Grendel for the 5 years that I have owned it, and it is night and day difference performance-wise compared to the .223 Rem.

    • shaw08

      Mostly because the idea is that the AR15 is the most common of the tactical rifle designs, atleast in america. So parts and accessories are inherently cheaper because its so common. While I like the AR10 and the abilities you get by stepping up the to bigger platform its a bit overkill once you know anything about ballistics and the applications of different bullet designs. Most people wont ever shoot more then 100m and if they do most of their targets are paper or steel. So if you can get a bullet that will provide the same or similar results out of a smaller platform using smaller bullets why lug around extra material? its the path of advancement that is the current market is all

    • julio

      6.5 creedmoor is superior to .308.

    • idiotfinder

      uhh… that is a VERY ignorant comment. 6.5 smokes .308 in every aspect, 5.56 smokes 5.56 for CQB, where maneuverability and fast accurate shots are king. .300BLK smokes it if you are wanting to run a suppressed and compact weapon… and by your very logic, the AR-10 should not get you warm and fuzzy. So tell us again oh wise one where your precious .308 is so great?

  • SaxMan

    Why not just buy an AR10 and shoot .308/7.62 and get something that will outperform all these cartridges? Sorry but shoe horning a cartridge into a rifle built for another cartridge doesn’t get me all warm and fuzzy.

  • clay blasdel

    The .223 is fine for defense but for survival (hunting) the .308 is a more versatile round. That means the AR10.

    • pwrserge

      There are very few things in North America that will not go down to a 5.56×45 78gr OTM.

    • Louis M.

      So, if I got some crazy ass coming to kill me I should have a .223 but if I want to shoot a rabbit or deer I best use a 308?

    • Norm Morris

      I tend to agree for larger game, but just checked out an article in G&A where a bunch of writers went hunting for big boars and even through and through shots with big bore cartridges (.45/70; heavy 12 ga slugs) were not as effective one-shot stoppers as a .223/5.56. I couldn’t believe it myself, but evidently those big hogs are much more sensitive to hydrostatic shock. Not saying a .308 wouldn’t be better for deer or elk, but just saying don’t discount the .223 Rem for a lot of game.

  • THE_SE7EN_SINS

    7.62×40 WT :)

  • bellinR

    .223 or Nato 5.56 was designed to poke holes in the enemy, not kill them.

    • wjkuleck

      Actually, Stoner designed the .223 to tumble and break in half inside the body. Increasing the twist of the M16 from 1 in 14 to 1 in 12 attenuated that effect to the point that Project Agile’s very satisfactory terminal ballistic findings in VietNam with the original Model 601s were never to be replicated.

      • Norm Morris

        ???? I have no idea what you just said.

        The orginal M-16′s were chambered with the same twist rate as the .22 LR. After all, they are both the same caliber within a thousandth, but the 55 grain 5.56 didn’t stabilize in such a slow twist barrel, so they changed it to 1:12. That still wasn’t fast enough, so 1:9 became the standard for 55 grain and 62 (SS109) bullets. Now with bullets running 70 and even 77 grains, 1:7 is the new defacto standard for stability, with a lot of 3-gun guys going 1:8 as a compromise. My only beef with the 1:7 crowd is that they insist that in addition to handling the heavier bullets better (true), the 1:7 also handles 55 grain just as well as the 1:9 (not true.)

        Stoner didn’t design the bullet to do anything you are saying, but the fast moving 55 grain fragmented like crazy. The North Vietnamese complained bitterly that the cartridge violated the Geneva convention (but of course pungi sticks were OK), because it fragmented and did so much tissue damage.

        The change to 1:12 made the bullet more stable, not less.

        • wjkuleck

          The standard twist for .22LR is 1in 16, not 14. Note that “attenuated” means “reduced,” so we are in agreement on the increased stability point.

    • USPatriotOne

      bellinR…You really got that one wrong! The 5.56 was designed to tumble and flatten out and by doing so causes max damage in the body. I don’t know how many times I have heard that the 5.56 went into the chest and came out of the enemies a*s or leg, and just think of all the terminal damage this round did on it’s way out! This round does the same damage to a deer as well for those that don’t believe the 5.56 can’t take down a deer! Do some research then write a comment. Sorry, but I don’t like dis-information and new shooters might believe what you have written as the truth.

      • Norm Morris

        USPatriot, it wasn’t “designed to tumble.” It didn’t tumble in any case; the incorrect barrel twist rate made the bullet unstable so it would keyhole. If it actually tumbled (which is the wildly common misperception) it’s effective range would be a few hundred feet.

        Fixing the twist rate fixed the keyhole effect and made the bullet more stable and accurate. Whether it was then less damaging I have no idea.

      • ditchdigger

        .22 long rifle does the same thing , at lower velocity. Works on targets under aroung 300 lb. Predators over 350 lbs, wild bovines over 900 lb. to 3000, deer,”Moose” to 3000 lbs, no toy rifles.

  • 3084Life

    I would like to own an AR15 chambered in 22-250: superior to the 223 in all aspects except maybe barrel life expectancy. Just throwing it out there. I would suggest shooting all calibers in question and choose the one you like the most. You know the old saying opinions are like assholes…we’ve all got em’.

    • ditchdiger

      Having shot coyotes with .220 swift, .22-250, .30-30, 30-06, ’45 acp, ,.44 mag, .22 and mag, even .45-70, shotguns. Mostly were targets of oppertunity, after predating on livestock or pets. Anything that will let the air out of them.

  • petru sova

    You forgot the .260 Remington way better than the anemic 6,5 grendel

    • Suzy QueBall

      Petru, this is an article on the AR-15, not AR-10 platform. The .260, being a .308-length round, fits neatly inside the dimensions of the larger AR rifle. No doubt it is much more impressive from a ballistics standpoint. The “anemic” 6.5 Grendel cartridge was designed around the dimensions and limitations of the AR-15 rifle, a firearm designed around the .223/5.56 cartridge, not to mention the Grendel harnesses the insane ballistic properties of .264 bullets. Anemic? Not hardly. Maximizing the capabilities of the AR-15 platform? Affirmative.

    • JvB

      Sure it’s better. But it won’t fit into the standard AR-15 receiver, which is what we’re discussing here.

  • Lee Larsen

    Except for the 5.56 all the others are compromise rounds designed to fit around the AR-15 platform. While most have merit they still remain compromise cartridges though I do like the 6.5 Grendel ballistics. If it comes down to a SHTF cartridge, I’ll stick with the 5.56 because it’s readily available and lighter to carry. Sure, it’s not the hammer of Thor but there’s a bunch of dead guys out there that can attest to it’s ability to end a fight.

  • CANRAY

    For the snickers and grins of it: has anyone considered the 9×39 cartridge used by Russian SWAT. Like the 300 Blackout, its range is limited, however, within 200 yards it’s got the knock down power of your uncle’s mule and feed problems are non-existant.
    I’m not making a statement here, but I’m curious as to whether or not anyone has considered this particulas cartridge?

  • CANRAY

    For the snickers and grins of it: has anyone considered the 9×39 cartridge used by Russian SWAT. Like the 300 Blackout, its range is limited, however, within 200 yards it’s got the knock down power of your uncle’s mule and feed problems are non-existant.
    I’m not making a statement here, but I’m curious as to whether or not anyone has considered this particulas cartridge?

  • Guest

    In my humble opinion, the.223/556 will always reign supreme. It has the versatility and s priced right to match any need, and It’s availability is stellar. Great for reloading, hunting, target shooting, matches, and self-defense, Its proven it’s usefulness, over and over again. While the other cartridges certainly fill a certain “niche” – my take is, the .223/556 will continue to be very popularity with a majority to shooters for a very long time.

  • GoldenClays

    In my humble opinion, the.223/556 will always reign supreme. It is superbly accurate, has great versatility and is priced right to match any need, and It’s availability is stellar. It’s really great for reloading, hunting, target shooting, matches, and self-defense. It’s proven it’s usefulness, over and over again. While the other cartridges certainly fill a certain “niche” – my take is, the .223/556 will continue to be very popular with a majority to shooters for a very long time.

  • petru sova

    Maybe if some of you arm chair commandoes read what “real hunters” did back in the early 1900′s like Agnes Herbert you would know what she proved i.e. that when comparing her 450 elephant gun to her 6.5 rimmed Mannlicher cartridge firing a 160 grain bullet at about 2,300 fps she found absolutely no difference in killing power proving that bullet diameter is totally irrelevant but shot placement and penetration are the key factors. Karamomo Bell said much the same after shooting 1,000 elephants, he said that the 6.5 WAS THE ONLY CALIBER HE EVER USED THAT ALWAYS WENT RIGHT THROUGH THE HEAD OF AN ELEPHANT AS THE BIG CARTRIGES FAILED TO DO SO. When a man shoots 1,000 elephants with the 6.5mm all the other peoples comments about the necessity of using big bore calibers are nothing more than hot rectum gas.

    I might also mention the turn of the century .22 Savage high power that fired an 70 grain bullet at 2,600 fps and they were killing grizzly bears with it.
    A friend of mine regularly kills big white tail deer out of his kitchen window at 200 yards with the 55 grain .223 bullet and they seldom move more than a few feet if they do not immediately fall down dead on the spot.
    And how about the supposedly anemic 9×19. I have killed 180 lb deer dead in their tracks with the Remington 125 grain hollow point bullet loaded hot with Unique powder. Dead is dead not deader no matter what caliber you use.

    • John Bush

      Penetration rules.

  • Steve

    Just a personal choice. I like the .308/ 7.62. Been using it a long time and see nothing that would make me change.

  • USPatriotOne

    First, I am a Certified NRA Rifle/Hand Gun Expert (going to instructor training soon), that being said I look for a few things when purchasing a weapon:

    1. What’s the main function I am purchasing this weapon for?

    2. Cost and Quality of the weapon?

    3. Replacement parts for the weapon?

    4. Availability of the Ammo?

    5. Rounds per magazine (5 to 30 round magazine or more)?

    6. Max effective range of the weapon? (With or without a scope and easy of use with both)

    I have fired several different AR15 platforms and evaluated these AR’s based on the criteria stated above.

    So from my research the best weapon based all of the above is the DPMS AR-15 AP4 Panther 16 Semi Auto Rifle chambered in both .223 Rem/5.56x45mm Rounds.

    1. The weapon being a Carbine (16″ Barrel) works well in close quarter engagements as well as having the pouch power out to 300 yards with very little bullet drop, and what drop is does have can be managed very well by a semi-experienced shooter. By no means do you need to and expert firing 800 to a 1,000 rounds of .223/5.56 rounds every weekend to manage the bullet drop.
    2. Found the DPMS AP4 Panther to be a very high quality weapon and the cost won’t break the bank either.
    3. Parts for the DPMS AP4 are available from a number of sporting resources!
    4. The Ammo for the DPMS AT4 is the .223/5.56. If the DHS and the Feds stop buying up all the Ammo, the .223/5.56 Ammo is cheap compared to other semi-powerful Ammo and normally available from nearly all sporting locations that sell Ammo.
    5. I like the fact that the DPMS AT4 (all AR15 can hold these types of magazines) can use 5, 10, 20, 30, and 100 Round Magazines, and you can a fit bump stock to this AR15 platform. Most rifles, in fact I don’t know of one, that has the ability to fit all this different magazines.
    6. The Max effective range for this AR15 platform is by far not the best, but for what most of what the common shooter wants this platform can’t beat it. Firing out to 300 yards accurately on a consistent bases with Iron Sights and out to 600 to 800 yards with a scope, in my eyes, says it all.

    I hope my evaluation helps anyone looking to purchase and AR15 platform, and NO I do not work for DPMS. Good luck and God bless.

    • John

      An expert and chose a DPMS????

      • Norm Morris

        Snort, guffaw!

      • MikeDH

        Given this article was about home defense use, not fighting wars in Afghanistan, I’d actually agree that the DPMS should be considered given the cost/role ratio. Someone in a once in a lifetime home intruder situation likely doesn’t need a Daniel Defense or Noveske rifle to get the job done. I wouldn’t be using an AR in that situation anyway, so YMMV.

    • Norm Morris

      By your own criteria a Colt AR, or a Daniei Defense or Larue or BCM AR, or my pre-ban Bushy or any other quality AR all meet the standard.

      Also, as far as I know (being an NRA Certified Basic Pistol Instructor and RSO), there is no such thing as a “Certified NRA Rifle Expert”, or a “Certified NRA Hand Gun Expert.” Did you mean to say you had taken the basic rifle / pistol courses? Or that you had shot “Distinguished Expert” in both? Neither qualifies you to say what you said, again IMNSHO.

      • LilWolfy

        I noticed the same thing. I’m also an NRA Certified Instructor in several disciplines, and familiar with the program. There is no NRA certified “expert”. The DPMS AP4 has basically not one single part in or on it that complies with the certifications required for a Mil-spec gun, and corners are literally cut on every part down to the detents to hit an affordable price point.

        If you just want a thing that looks like an AR15 and sits in the safe, that can be taken out and make it through a few mags in slow fire over a few hours, it’s fine. I have torture-tested DPMS carbines across temperature ranges, and the aluminum gas blocks are one of the first failure points. The barrels actually tend to be quite accurate with the bull profiles, but 6000-series aluminum, low standard FCG, non-certified bolts, cheap barrel extensions, cheap springs, and cheap everything don’t come together like you would expect.

    • Guest

      When you mentioned a bump stock your predictability plummeted.

    • John Bush

      When you mentioned a bump stock your credibility plummeted.

      • Rob Joblin

        Have one, bolted it up, then LAUGHED AND LAUGHED, AND LAUGHED. It’s for sale, if you want to buy one… :)
        (And I have a Noveske barrel made from m-249 machine gun steel, double thickness chrome lined that shoots 1moa) Yeah, that barrel could take a dump and be fine, but still THE STUPIDEST THING I EVER BOUGHT PERIOD.

        • Derek Shea

          how much you want for the barrel?

          • Rob Joblin

            Sorry, couldn’t sell that rifle. Will keep for the rest of my life, just used it as an example because it is one of the few that can stand up to the kind of abuse a bump-stock and 100rd clip can deliver….

    • John Bush

      Kind of a blowhard, arn’t you?

    • John Bush

      It is painfully obvious from your rant that you have never been in the military, but how many merit badges do you have?

    • huntingdave

      DUD, oops I mean Dude, do you know what mil spec is? All basic AR platforms are created equal. I personally can guarantee you DPMS is no better than White Oak Armament or most any other manufacturer you probably don’t know of. Personal mods like, premium barrel and free-floating are paramount for precision. Don’t want you instructing me, you don’t know Jack but appear to be very opinionated, HeeHaw.

      • SaxMan

        If they are built to mil-spec. A lot of AR’s aren’t built to mil-spec.

        • LilWolfy

          Not one part or assembly method even is Mil-spec on the AP4′s. I could literally go through every single component, from the pistol grip to the detents, springs to the barrel, muzzle device to the extension tube, and list why and how each part is not even close to Mil-spec.

          This goes for almost every AR15 manufacturer on the market. They couldn’t be bothered with material certs, coating certs, metallurgy processes, assembly methods, and testing. That’s for suckuh’s who actually want to make a quality product that will work in cold weather, mag after mag.

  • oldbill

    I had my first M-16 in 1967 when I went through Vietnam Familiarization at Camp Pendleton. I didn’t particularly like it. I was used to the M-14 and when I arrived in Vietnam, I was issued a selectable M-14 which served me well for thirteen months, when I extended. When I go back they issued me an M-16. Not quite as bad as the earlier “muzzle loader” M-16, I didn’t like it. You clean it and lube it and watch it corrode as you are looking at it. I was used to taking my M-14 into the shower to clean it! I now have three AR’s and two AK’s. In a real gun fight, I would rather have the AK. I have built an AR in Blackout, and I really like it for most rifle functions under 200 yards. I have made 1,200 cartridge cases out of 5.56 blanks and there is a huge range of possibilities. I am using 110 grain 30 Carbine lead bullets for target practice and they work great. I have tried up to 150 gr jacketed, and I have casting molds for up to about 210 gr. I think I will convert one of the other AR’s to Blackout.

  • Sivispace

    I like the .300 aac because it uses the standard bolt. It is quite effective out to 300 meters and is easily suppressed. When suppressed and firing subsonic ammunition, the report is similar to a suppressed 9mm with quite a bit more kinetic energy which makes the subsonic .300 aac frangible round an excellent round for close quarters battle indoors.

  • Tim-LV

    I’m happy with the 450 Bushmaster. Then again I’m a big fan of the 45/70.

  • Dave

    243 or 7mm 08 would be the best

  • Dave

    243 or 7mm 08 would be the best

  • Dave

    243 or 7mm 08 would be the best

  • Tortoise

    I’ve been shooting the 338 Federal for awhile now and I think it’s become my go to round for my main AR….. my Bushmaster in 5.56 is feeling a little lonely lately…

  • Tortoise

    I’ve been shooting the 338 Federal for awhile now and I think it’s become my go to round for my main AR….. my Bushmaster in 5.56 is feeling a little lonely lately…

  • Tortoise

    I’ve been shooting the 338 Federal for awhile now and I think it’s become my go to round for my main AR….. my Bushmaster in 5.56 is feeling a little lonely lately…

  • 308plinkerVT

    straight up SHTF – 5.56 is going to be king, projectiles make is useful all round if you’ve been truly paying attention. if you can pillage, uh, borrow from, stockpiles across the country, supply will be near always be there. best case scenario though – 5.56 for up to mid range, 300 blackout for close and quiet. in a cool world where 6.5 is as plentiful as 308, then add that one to the list. until then 308 will be as plentiful (in those hordes of course…) as the 5.56, and just makes more sense. call me crazy.

    • MikeDH

      Agreed.

  • 308plinkerVT

    straight up SHTF – 5.56 is going to be king, projectiles make is useful all round if you’ve been truly paying attention. if you can pillage, uh, borrow from, stockpiles across the country, supply will be near always be there. best case scenario though – 5.56 for up to mid range, 300 blackout for close and quiet. in a cool world where 6.5 is as plentiful as 308, then add that one to the list. until then 308 will be as plentiful (in those hordes of course…) as the 5.56, and just makes more sense. call me crazy.

  • JuhHeard

    .338 federal

  • JuhHeard

    .338 federal

  • JuhHeard

    .338 federal

  • CrusaderII

    I picked the .300 AAC Backout because it reminds me of the .22L when compared to a .308 Winchester/7.6 NATO round = not all the recoil of a .308 Winchester/7.62 NATO BUT sill a VERY effective round within it’s range limitiations.
    Plus I can reform my .223 Rem/5.56 NATO brass into .300 AAC Blackout which is a HUGE cost savings right now considering that there is hardlay any .223 Rem bullets (projectie part) to be had BUT there are plently of .30 caliber bullets to be found.

  • Chris

    It would be nice to see the 6.5 Whisper standardized like the 300 Whisper was with the introduction of 300 Blackout.

  • Ce`arr

    Talk about drinking the kool – aid …….. give the troops something decent for Christmas, a 6.5 Grendel with a 140 gr. spitzer boat tail. 20 round mags don’t matter so much when you can stop with one shot. What difference does it make to carry more rounds of a cartridge that can’t stop a large angry man intent on stuffing a grenade down your throat with one shot. Doesn’t anyone remember the .38 Colt? The Moro’s ? Colt .36 Navy’s and the Sepoy Mutiny? Doesn’t anyone remember past battles? AM I THE ONLY ONE WHO GETS THIS? ….kool- aid…jebez……

    • Practicaltac

      How many people have that one shot ability, this isn’t the movies. The fact is round counts matter, you can carry a round that takes up twice the space, weights more, and doesn’t make the other guy any more dead. Check the battle field those bodies can’t talk but they still tell a story! CHECK YOUR HISTORY…

      • truth will out

        You do know the US marines now do 2 shots to the body, one to the head, don’t you ?

        So much for your 30 round magazine which is now effectively 10.

        Its NOT just about killing people, its about hurting them so badly that they stop (unable) fighting. Instead of falling down, and then getting up after you are passed them and trying to re-engage you.

        The 5.56, despite its success, has a long history or not stopping people reliably. There is a reason its banned from hunting in the majority of States. That should be a clue for you.

        And don’t even begin about barrier penetration.

  • Ce`arr

    ….pass me the rum, Purity, I needs a drink…..

  • Ce`arr

    And while I’m on this jag, the M-14 is a GREAT Rifle…….the AR series is an example of shameless Foggy Bottom lobbying.
    Take the M-14 and engineer it down to 6.5 Lapua size. Do the same with the FAL. A hero’s tools for a new age. Remember too, troops become attached to their weapons. At that point, looks matter. The M-4 is the Bride of Frankenstein. Moulded plastic and ergonomics by Thalidomide….eeccch.

    • Spyderman

      I thought the article was geared to civilian use by hunters. There is no argument that the M-14 is a fine rifle, but the discussion is about the AR platform and AR cartridges.

  • Ce`arr

    Thanks for the ear, Ladies and Gentlemen, that’s been festering for a long time.

  • Norm Morris

    Uh, can anyone say 7.62X39 upper for your AR? I don’t get why anyone would spend for a pricy upper in a more expensive cartridge when the 7.62 Russian has been doing the job better and far longer.

    • KissMyRangerPanties

      There is a reason that 7.62X39 is not on this list….which is even mentioned by the author: It’s not a good choice for the AR platform. It works great in lose tolerance platforms like the AK and SKS… no one can really argue that; but it has too many inherent problems in AR’s, to be in this particular conversation.

      • Stan

        I have built over a dozen 7.62X3 AR’s. They run great, hit hard, twice as heavy bullet, more accurate in the AR platform than the AK, and ammo is cheap and available. Reliability is as good as any 5.56 AR. NO PROBEMS !

      • Patrick Moran

        Ranger is correct,I used to own a Colt Ar in 7.62×39 and it had bullet feeding problems all the time.This was about 1992 when you could still get the Chinese Norinco ammo in the yellow boxes.

  • Doug

    Shot Placement & knowing your limits……..

  • pwalker1

    ar in .223/5.56 and another in 7.62/.308.the new colt convertible looks tempting but if it breaks well-one is none and two is one

  • Spyderman

    I don’t think there is a “best” cartridge for this rifle. It depends on how the rifle is to be used, recoil factors, max range requirements, wind factors, reloading capabilities of the shooter, availability of brass, bullets, etc., frequency and amount of shots taken and so forth.

    I chose a .223 because I already had the dies, had tons of bullets, primers and brass for reloading, plus I can shoot ground squirrels and coyotes….which is why I like the cartridge. To use a larger cartridge on ground squirrels is foolish, especially when a few hundred shots per day might have to be taken. The caliber is a good all-around one for coyotes and similar-sized animals up to 250 yards or so…..and at maybe even even greater ranges for more-experienced shooters in low-wind situations.

    The article should have separated out the .223 and asked for opinions only on favored cartridges that are larger than the .223. To include the .223 in the mix really skews the results.

  • Billybob

    I just keep hoping the 6.5 Grendel will catch on. It is fantastic round.

  • Charles Raymond Mccaleb

    Where may I find 357sig ammo

    • Rob Joblin

      I make it in my garage. Use AA#9 for compressed loads at around 12g-13g. You need to long form the cases every reload to ensure reliability. Don’t forget a factory crimp die, you need one for that cartridge.
      ]

  • budhall

    The best cartridge for the AR..??.., well that’s easy….it’s the one the rifle in your hands is chambered for. At the moment you need the rifle, the question becomes purely academic.

  • Ron

    I have a 9mm upper and it is great out to about 150 yards. I do have to do my own custom hot loads and use Hornady 121gr 9mm HAP bullets for that kind of accuracy. However, I can get 10/10 headshots on a target at 100 yards shooting off a bench with a red dot with that load. The other big plus is that I can load those rounds for ~$0.18/rd if I buy the HAP bullets in bulk, i.e. they’re cheap. The bullets, powder and primer are all standard stuff and easy to get and you can easily scrounge a couple hundred 9mm cases in one session at any pistol range. You just need a little extra powder charge to give it the kick it needs on a 16″ barrel.

    The main drawback is the need for a 9mm AR SMG magazine adapter. The upper will work with standard 9mm pistol loads, but accuracy is pretty marginal.

    For all-around versatility, I’d still have to go with the 5.56mm especially if you have hump around with several hundred rounds since a 5.56 is half the weight of a 7.62×39 round.

    LR-308s are cool, but for the 99.999% chance that the zombie apocalypse WON’T happen, ammo gets expensive really quick (not to mention heavy). If I need to reach out and touch someone at 400+ yards, that is what I have my Remington 700/308 for. :-)

  • Christiano

    Absolutely..rightly said @Adaris, @disqus_Cw32IOAVDp:disqus

  • Christiano

    I will always preferAR 10 rather than using AR 15 as it provides with much more horsepower

  • Christiano

    Alternately the AMS-SRC Stryke Series SR15-A4 Carbine AEG Airsoft Rifle
    is a much better option than AR 15…
    The SRC SR15-A4 Carbine features a fiber polymer reinforced receiver, providing higher build quality and is significantly more durable when compared the ABS bodies of Tokyo Marui AEGs. The receiver features a higher density than most standard receivers, and as a result, is more durable and less prone to cracking or breaking due to an inadvertent drop or collision.

  • rdsii64

    When it comes to defending my house, At any distance that a jury of 12 is likely to believe that I had no other reasonable choice, it doesn’t matter which one of those cartridges your carbine is chambered for. My choice is plain jane 556. Its plentiful, cheap and will kill you grave yard dead from any distance you can reasonably make a self defense claim.

  • Some guy

    Some things the author might be unaware of:

    1) The drawback of 6.5 Grendel’s performance….It requires super long barrels to work. While the 6.8 SPC and 5.56 works fine from 16 inch barrels, 6.5 grendel performance falls off horribly below 20 inches and only really puts out decent numbers in the 24+ inch range. Those fat cartridges require slow burning powders to avoid breaking stuff.

    2) 6.8 SPC is a great subsonic load if you use a high twist barrel. You can stabilize 200 grain subsonics with a 1:7 barrel. There is a company making uppers to this spec. The only downside to 6.8 SPC compared to 300 BLK is that you get slightly less mag capacity.

    • barccy

      The Grendel retains its ballistic advantages of greater energy and velocity retention and less drop and windage variation over the 6.8 and 5.56 even in 16″ barrels. The Grendel often uses powders like BLC2 and CF223, which are used extensively in .223 and .308, and aren’t all that slow burning.

      http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

      The 6.8 requires different magazines (and can only use pmags, arguably the best AR mags, with a non-standard lower) and bolts. .308 bullets and 5.56 / .223 brass are more common and cheaper, at least when when surplus and used brass is taken into account.

    • DaveS

      Clearly, you’ve never shot the 6.5 Grendel. There are reports of 16″ Grendels with terrific performance and accuracy that are too numerous to count. There are even documented cases of these 16″ barrels putting rounds on target out to 1200 yards. Not too shabby, in anyone’s book.

    • LilWolfy

      That’s one of the internet myths that has been floating around and just seems to never die. The 6.5 Grendel actually works really well from even 10.5″ barrels. A 14.5″ or 16″ Grendel will still get you out to 900-1200yds for supersonic speed with factory 123gr ammo. No really, I’ve done it. I wouldn’t have believed it myself had I not been behind the trigger and scope.

      6.5 Grendel performance does not fall off horribly below 20″. There is no data to support that at all. The fat cartridge with 30 degree shoulder burns its powder very efficiently, and the medium-slow powders do very well with long projectiles, even with Mid Length Gas Systems and 16″ barrels.

      Does 2550fps with a 123gr .510 BC sound decent….from a 16″ barrel? So I can shoot long range with my little carbine, then turn around and hunt with it with an assortment of projectiles that is at least over 85 hunting pills, aside from the scores of target pills that rival .30 bore for BC easily. You start to see why this cartridge is stirring such debate when you get behind it, because you have a hard time believing that 27-31gr of powder is getting a bullet to do what it does.

  • ACS

    I like the Rem. 7mm-08

  • NicholastheWise

    Whatever happened to the 6x45mm?

  • John

    6MM Hagar or 220 Thunderbolt ( simply a Hagar necked down to .224 dia)

  • Knitepoet

    Owning both 223/5.56s and a 6.5 Grendel, I still chose the Grendel as MY favorite.
    Though you left out the heavy hitters. Of them, I have a 50 Beowulf. It’s a BEAST inside 150 yards

  • Sam

    Saying the 300 Blackout hits harder than the 6.8 with the same size bullet is a pretty stupid comment. If both are 110 gr. and the 6.8 has a higher velocity, simple math says the 6.8 has higher energy.

  • robs44

    6 x 45mm, still affordable varmint bullets, brass easily converted from .223, can use heavy weight hunting bullets. 6mmAR is my second choice, but not as easy to get grendel brass to make it.

  • shaw08

    As the article mentions every cartridge has its strenghts and weakness. Most of these are limited by the magazine length of the AR15 platform. I caught on to some forums about the various wildcats off of the .223Rem cartridge a while ago and ended up in some that push the limits of the AR15 to its max. My opinion for the best cartridge would be the BHW 6.5×6.8. it is simply a 6.5mm bullet that is known for its great BC seated into a 6.8 casing. The reasons why I think its the “best. You get all the pros of a 6.5mm projectile with vary little changes to the AR15. While the 300blk does a better job at keeping almost all the same parts it significatly lacks in velocity(granted it was designed to be for a supressed gun). Youll get increased penetration and terminal ballistics on your target as opposed to 5.56. It mimicks the trajectory of the 6.5grendel without the bolt breaking and feeding issues. The only cons are you need to change the barrel, bolt, and magazine follower. So more then likely it will be a dedicated caliber gun, not something you switch back and forth from like the 300blk, or 6×45.

    But when it comes to the AR15 and the reason most people own one, no caliber will beat 5.56. Even with the marketing that 300blk has been able to put out, the lack of ammo makes it hard to give up 5.56. And no matter what any gun “guru” tries to tell you about the US miltary planning on chaning caliber, DONT BELIEVE IT. The US, all of its allies and NATO have went to great lengths and great cost to make 5.56 and 7.62 the standard round for centuries to come. The amount of money it would take to switch calibers would be unimaginable. And nothing in the realm of modern technology will provide enough added performance to make that change.

    • LilWolfy

      You lose most of the bullet options with the 6.5×6.8 because of case length. You also can’t push the pressures enough to compensate for the Grendel’s performance advantage because of bolt thrust and hoop strength of the barrel tennon.

      Metallurgy and higher standards of QC equate to very long-lasting bolts in the Grendel and 6.8 SPC, just like it did for the 5.56 NATO versus the .222 Remington that the AR15 was designed around.

      If you want to use 6.5mm in the AR15 with as many projectile choices as possible, you mustn’t exceed a 39-40mm case length, and need a certain amount of case capacity for performance. Hence the 6.5 Grendel.

      • shaw08

        yes compared to the grendel the 6.5×6.8 isnt as good but then again the grendel isnt as good as the creedmore either. The reason why I think the 6.5x.68 is a little better then the grendel is that you dont have as many issues with the 6.8 casings as you do with the grendel casing, and you get slightly higher mag capacity. But as I mentioned in my first comment neither are as good as the 5.56 when it comes to practicality because of the shortage of both grendel and SPC bullets. But if you want to make this purely about ballistics then why bother with the grendel why not go with the 6.5 br or something of that nature?

        • LilWolfy

          There are no issues I’m aware of with the Grendel case. It works. CM won’t fit in the AR15, and gives you 90-150yds more range in comparison, both being supersonic well past 1000yds, so then you ask, “Do I really need to be supersonic at 1400yds?” Some people do, most will never see a range in their entire lives that far.

          With fatter cases, we are pushing too far with the AR15 barrel extension/upper receiver/ and barrel tennon diameters in terms of hoop stress. The Grendel and 6.8 are already pushing the performance capabilities of the steel to the limits. That’s why the Grendel is kept to around 50,000psi chamber pressure, even though the case will take 60,000psi no problem. It isn’t the bolt that we’re primarily worried about, it’s the barrel tennon.

          With a carbine being able to reach 1000yds with authority, who really cares though. It turns into a pole-vaulting contest over mouse turds for those that aren’t out actually shooting, whereas those that do just enjoy the performance and keep shooting. I have 4 Grendel’s to take out this spring for some more fun. Factory ammo availability is making it hard to justify reloading for, even though I planned on only reloading for the Grendel from the start.

          • shaw08

            Im not sure if its still an issue, but back when I started researching the grendel the main issues were feeding problems because of the fatter case and the bolts were breaking either because of pressures or because of the metals used to make the bolt. I know some guys who have grendels and using good mags and the right follower they dont have any issues.

            But like you said were getting into a pole vaulting contest over mouse turds. Quality 5.56 will reach 800m, it doesnt have much energy at that distance but I’ve never given the knock down energy argument any validity because I know from experience it doesnt matter how much energy a bullet has its where you put it.

            Also something you mentioned that we are starting to push the upper reciever/barrel of the platform to its limits. DPMS has started making an AR15/10 variant that uses mostly 15 parts but shoots 7.62nato. I havent seen much on them so far I think its called the GII series. This has really gotten me interested because that would combine the best of both worlds when it comes to cost and availability of parts. If they are as advertised now you’d be able to just buy a new lower and use whatever parts they have changed to be able to push remington 260′s which would make this topic a thing of the past.

          • LilWolfy

            GII doesn’t use AR15 parts, other than the FCG, extension tube, and some of the furniture. It’s a totally different animal in regards to size of the components, and none of them are compatible with anything else on the market

            .260 Rem performance brings with it pressure and recoil penalties, for marginal increases. I have both, and my Grendel is supersonic past 1300yds, while the .260 Rem is supersonic past 1500yds with the same bullet.

            Powder consumption is significantly more with the .260 Rem, about 10 grains greater, and recoil is much closer to .308 Winchester. Rifle and magazine sizes are much larger, so they are less easy to carry.

            5.56 will get to 800m, yes, but it is extremely unpredictable with the wind deflection at that range, whereas the Grendel is not.

          • shaw08

            The article I read on it said the both recievers, fire control group, and furniture was the same, the only thing it spoke of that wasnt mil spec was the barrel extension and one other peice I cant remember off the top of my head. But we have both seen how even the best of ideas havent gotten anywhere on the market because they are too different…

            Now your starting to talk about some of my biggest pet peeves, size, wieght, and recoil. All of which are not significant between the two platforms, yes its more but its not that much more. Wolfy Im starting to get the feeling that you dont really care what we talk about, as long as you get to say that your opinion is better. Ive carried quite a few firearms platforms over very long distances with redundant ammounts of ammo. None of them was any more fun to carry than the other in a military application,since if I was carrying less in respect to guns, or ammo, it was made up for with other gear so the ones carrying more guns, and ammor could carry less gear and vice versa. The recoil of the .260 is about half of that of a .308 in my opinion without a muzzle break on either. Now add a can or compensator and it goes away pretty quickly. And complaining about recoil from any short action is really just nit picking, even when shooting heavier bullets. I’ve shoulder fired .308 guns between 5 and 200m and its really not that hard to engage quickly and accurately using the right techniques. The reason these are my pet peeves, is because there are a lot of people in the civilian market that find it easier to just buy another caliber gun or another uneccessary accessory to compensate for their lack of experience, and if it doesnt help then its still the guns fault in their opinion.

          • LilWolfy

            DPMS GII receivers, Bolt Carrier Group, barrel extension, barrel nut, and charge handle are totally unique to the GII. I’ve spent a lot of time going over the components by hand, to include all 6 of their introduction models of the GII.

            As to opinions, I don’t really see the relevance of one in this discussion when it comes to technical facts. Either the facts are what they are, or they aren’t. I actually prefer 5.56 currently for home protection, proceeded by my pistol with a light, but for a general sense of one AR15 cartridge to do it all, the Grendel is the current factory offering to beat in terms of performance in a compact, lightweight package.

            I too have humped a boat load of weaponry all over the globe, to include a laundry list of foreign weapons, in places most couldn’t find on a map, across all environmental conditions, in almost every duty position you will find in a Light Infantry, Airborne, or Reconnaissance unit. It’s one of the main reasons why I’m not a big fan of the 7.62 NATO.

            I’ve spent 20 years behind machine guns, assault rifles, sniper systems, SMG’s, anti-armor weapons, and sidearms, and I can tell you for a fact that the .260 Remington’s recoil is comparable to a .308, especially with 140gr projectiles at 60,000psi, compared to 147gr in the 7.62 NATO at 58,000psi. I’ve owned several of each. Recoil may not be an issue for your physique, but in a light rifle, when it comes to training, recoil is a significant consideration. Current trend within SOCOM is going to lighter Semi Auto Sniper Systems, with 16″ barrels, telescoping stocks, compact optics, and higher BC projectiles a la KAC M110K.

            http://pro-patria.us/yahoo_site_admin/assets/images/M110K1_w_can_and_cqbss.33102508_std.JPG

            If we are talking appropriate calibers for military small arms, I think that’s a different discussion than civilian use, and one that needs to come well after a serious sit-down on training, force structure, doctrine, logistics, and the geopolitical forces that will drive future conflict.

  • John Brown

    Both the 6.8 and Grendel need dedicated mags to feed property. Precision Reflex, C Products Defense, ASC and Magpul make 6.8 mags. ASC and C Products Defense make Grendel mags.
    The 6.8 and Grendel both “hit” much harder than the 300 bLk Joseph. If you use the same weight bullets in the 6.8 or Grendel and 300 you would see the 6.8 is 150-200fps faster. The same weight bullet 200fps faster will have more energy. Please do some research before writing tech articles.
    “It shoots more bullet weight faster than either the 6.8 SPC or .300 Blackout” Saying that after saying you are biased toward the Grendel makes that a flat out lie.
    Any time you want to prove that the Grendel shoots heavier bullets faster than the 6.8 out of the same length barrels just come on over to 68forums and make the offer to meet at the range I’m sure several will take you up on the offer.
    The 6.8 when hand loaded can push a 120gr bullet to 2800fps out of a 20″ barrel. According to Alexander Arms and the loading manual published by some of the guys on the Grendel forum the Grendel can only push a 123gr up to 2550-2600fps out of the same 20″ barrel.
    The Grendel according to Bill Alexander should not be loaded to pressures over 52,000 psi to keep the bolts from breaking and not reach the maximum hoop stress limit in the weaker stainless barrels since the cartridge is larger in diameter than the other cartridges and the chamber walls of the barrel are so thin. Even the 5.56 in a stainless barrel does not have a safety factor of 2:1 that the military requires. The 5.56 and 6.8 need 4150 11595E steel to meet the 2:1 safety factor.
    The Grendel using Lapua match bullets may have better exterior ballistics than a 308 using 175gr military bullets but use Lapua match bullets in the 308 if you want a FAIR comparison. By cheating you can sway any outcome, compare them fairly to learn the truth.

  • no

    If cost and availability was not a concern, and all things related to that being equal, then 6.8 SPC is probably the best mesh of long-range performance whilst still being controllable for up-close work. The problem is cost, availability in bulk, and cost of the platform. A close second would be the .300 BLK out of a 16″ barrel which is slightly better, ballistically, than the 7.62×39. Out of the two, again in a perfect world, I would probably opt for the .300BLK with a 16″ barrel and sacrifice on the longer range performance in order to keep 30rnd mags as opposed to 25rnd. .300BLK also is very versatile in that it is fully stabilized by 8-9″ and can be loaded sub-sonic to be very suppressor friendly. It also sticks very close to the original design of the m4 (m16/AR15…whatever you want to call it) and to me, that is a plus because you can realistically keep a 5.56 barrel around and swap back and fourth… although not recommended, it is technically possible. All that makes it a very versatile round. All that said, we don’t live in a perfect world, and parts availability, ammo availability, and cost is a huge consideration TO ME- 5.56 is it for me… at least until I can get a case of .300 BLK for $300 and it becomes widely used by NATO, and LEO across the country. So I guess in the end, it depends on the person and their mission.

  • Peter Orlando

    Can someone just give me a straight answer. I want an ar15 for plinking and defensive purposes not hunting. What caliber would I need to get Shots maybe out to 200 yards. I am not a reloader and would buy ammo straight up from a gun store.

    • Grendel Medlord

      Get a standard .223/5.56 and never look back. They are cheep to feed, proven effective man stoppers and plenty accurate out past 300 yards.

  • Spyke Gunster

    My Sig 716 weights 9.5 lbs empty. That’s why I don’t hump around a .308. The 300 blk is the best

  • Kir Rich

    It seems to me that each cartridge would be used for different purposes or situations. The lighter 5.56/.223 is readily available and a lot more rounds can be carried than the heavier, larger calibers. The 6.5 may shoot farther and flatter and outperform the 6.8 at distance, but for CQB, the 6.8 is more effective for stopping power. Even a .22 fired from a firearm with a silencer has it’s uses. An argument could be made for any caliber round, it all depends on what you need it to do.

  • Michael Muha

    .50 Beuwulf

  • Andrew

    50 beowulf

  • Michael Moniz

    If I had the cash to drop, for home defense, I’d go 300 Blackout using
    subsonic rounds in an AR pistol, 8″ barrel with suppressor and the SB15
    brace

  • Tom

    6.8 hits a LOT harder than 300blk!!!!!!! And I own a 300. Would love to see 6.5 take off.

  • Noah Ford

    i have a question about difference in ammo, there is an ammo that cost $8.99 (the pmc) and the Hormandy that is up to $20 dollars. is my gun at risk from shooting the cheaper ammo?

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