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CORE 15 Hardcore AR Review

The Hardcore is the flagship rifle of the Core 15 brand.

The AR market is awfully crowded these days, so it's hard for any one company to stand out. A lot of manufacturers rely on adherence to military specifications set back in the late 1950s to do the heavy lifting on the marketing side of the house. While I harbor no ill will toward Mil-Spec rifles, modern techniques and materials (not to mention several decades of experience with the design) allow those willing to push the envelope to build a better AR-type rifle, such as CORE 15.

CORE 15 is a small company located in Florida that has been growing fast and working hard to continuously improve its product line. While it was once similar to many other boutique AR manufacturers, it has progressed into a company capable of offering premium products designed and built almost entirely in-house. This transition resulted from an accumulation of AR tribal knowledge that comes only through years of experience and willingness of upper management to take risks in the quest for better, more relevant products.

The bolt and bolt carrier have been coated in nickel boron, an exceptionally hard material that is also very slick. The coating makes cleanup a snap and helps keep parts from seizing when the gun gets dirty.


CORE 15 has been building AR-type rifles for more than five years, surviving the volatile swings associated with this market. With the lift of the assault weapons ban in 2004, ARs quickly rose in popularity. Their light weight, potentially generous magazine capacity and modularity made them desirable for any use from home defense to hunting.

Unfortunately, ARs have also been the target of unjust scrutiny from politicians and the media alike. When the political landscape changes and it appears there might be additional gun legislation on the horizon, the AR market experiences wild swings in demand.

As long as legislation appears imminent, there is no end to demand. This causes the big forging houses that make the unfinished receivers to start cranking out product as fast as they can. They cut corners to maintain the production line, which means that a lot of the forgings they try to dump on AR manufacturers such as CORE 15 are substandard. Also, if the heat treat for these forgings is done incorrectly (which occurs with greater frequency when trying to ship as much as possible out the door), the forgings will warp once manufacturers start cutting on them.

The Hardcore 15 is finished in gray Cerakote, a hard ceramic finish that wears like iron.

There are a couple of ways a company such as CORE 15 could and did survive in that kind of climate, and both are painful. One is to run exhaustive quality control on the forgings as they come in and send back anything that doesn't look right. This keeps CORE 15 viable in the market, but it also means some potential lost revenue by not just accepting and selling everything it can get its hands on.

The other way to survive is to bring as much of the manufacturing as possible in-house. This makes CORE 15 impervious to the type of supply-chain chokepoints that occurred during past periods of peak demand. Historically, those chokepoints have been barrels and receivers. A lot of backorders occurred because there are only a few barrel and receiver makers out there.

The downside of bringing barrel and receiver manufacturing in-house is the additional expense from the overhead. In effect, a manufacturer has to be really committed to quality control and long-term presence on the market to make this type of investment. CORE 15 recently unveiled its new Hardcore model, showcasing its new billet receivers and the barrels it makes in-house. This rifle is the flagship model and the direct result of years of hard work and a commitment to building only the highest-quality rifles.

Core 15 is now making its own barrels, and this 18-inch fluted model shot extremely well.

Barrel Magic

There's witchcraft involved in barrel making. Any other aspect of a rifle comes down to good old-fashioned manufacturing using quality materials, but there really seems to be some black magic involved in turning out a good barrel.

Barrels are the source of about 80 percent of a rifle's accuracy. There are some well-known barrel makers out there, and most have a healthy backorder. They will also require that our gun make a visit to a quality gunsmith before we can take advantage of said barrel.

In a perfect world, manufacturers would make (or have never-ending access to) their own premium barrels and put one on each of their rifles. This way, we could buy from the factory and not have to ship our new acquisition to a gunsmith if we wanted maximum accuracy right from the start. I know of very few manufacturers willing and able to do this. CORE 15 is one of those companies.

The rubber Hogue grip mates well with the triggerguard and lower receiver.

I visited the CORE 15 factory as part of my research for this article and spent some time watching how it made and finished its barrels. Each CORE 15 barrel starts out as a length of 4150 steel that gets drilled to form the bore. The barrel's next stop is the button-pulling station, where the appropriate button for caliber and twist rate gets selected and placed in the machine. Pulling the button and rifling the bore only take a moment.

The barrels then move to a CNC machine that begins the contouring process. There are a couple of steps here, but each one only takes a couple of minutes. The last step is cutting the chamber and the crown, which is done in the same general area.

Drilling the bore, cutting the rifling, contouring the barrel and cutting the chamber and crown are only part of what it takes to make a good barrel. The other key component is the heat treating process (this is where the magic happens). I didn't see the heat treat process that CORE 15 uses, but it's a complicated step that should probably be kept a secret anyway. Just being able to watch each step of how the barrel was made was enough of a treat that I couldn't wait to see how it shot. I was pleasantly surprised, but more on that later.

The midlength gas system and Lantac muzzlebrake almost completely eliminated recoil.

All of CORE 15's rifles will ship with its barrels on them in the future. The 5.56mm rifles are all shipping with CORE's barrels on them now, and the 7.62mm barrels will probably complete the transition by the time this article hits the newsstand. The plan is to use 4150 steel on all models and finish them with Melonite. I think this is an excellent choice, especially now that I've seen how well they perform.

Not Just Barrels

While the most exciting news is the movement of barrel production in-house, CORE 15 is now also making its own upper and lower receivers out of billet aluminum. We've discussed some of the headaches associated with using forgings, and the move to billet solves all of those problems.

Billet aluminum receivers start as a solid block of aluminum that gets milled down to the exact dimensions needed. The process gives manufacturers the opportunity to create the exact shapes they need, but the trade-off is that it takes a lot longer to machine away the excess material, so the cost goes up. This is why we only see billet receivers from the more committed AR manufacturers.

The billet aluminum receivers allow Core 15 to shorten the magazine well, utilize an integral triggerguard and have some fancy machine work on a normally plain upper receiver.

CORE 15's latest offering, the Hardcore, comes with the new billet receivers and CORE's own barrel. The receiver set is an excellent foundation for the rifle, and the barrel is 18 inches long, fluted and carries a midlength gas system. The midlength gas system is superior to the more common carbine length because the midlength system places the gas port farther from the chamber, reducing the pressure (and speed) at which the direct-impingement system operates. The speed reduction greatly prolongs bolt life.

The Hardcore ships with a single-stage CMC trigger that is very crisp and breaks at 3½ pounds. The flat trigger shoe with a 90-degree turn at the bottom creates very consistent finger placement when we desire maximum precision. Also standard on the Hardcore is an ambidextrous safety selector.

CORE 15 also brought Cerakoting in-house and will now offer various finishes on some of its rifles. Cerakote is a very hard ceramic coating that must be baked on to completely cure. It is by far my favorite finish on any rifle. It has excellent corrosion resistance, can be had in almost any color and is almost impossible to scratch. The rifle seen here is finished in gray.

The Picatinny rail section that runs the top length of the rifle has been inletted.

Not wanting to leave any surface untreated, CORE 15 also coats the bolt-carrier group with nickel boron in each of the Hardcore rifles. This treatment has exceptional surface hardness while still retaining a high degree of lubricity. The result is a bolt-carrier group that is easy to clean and can still function even after the lube burns off. 

At the Range

Taking the Hardcore out of the case at the range, I was reminded why I greatly prefer the new KeyMod forends over their older quad-rail counterparts. The forend on the new Hardcore rifle is much more slender than a quad rail, yet it still free floats the barrel. We get all the accuracy we're used to without the bulk of the older system. The KeyMod slots along the sides and bottom make it possible to attach sections of Picatinny rail just where we need them should we want to mount a bipod or light on the rifle.

The KeyMod handguard is very slender and sits comfortably in the hand. The lean shape also lends itself well to positional shooting.

I was genuinely excited to see how the new CORE 15 barrels would do, especially the fluted version on the top-of-the-line model. While I was visiting the factory, I saw the company armorer take two of CORE's cheapest rifles off the rack and accuracy test them in a fixture at 100 yards. Both rifles had nonfree-floating barrels, yet they still grouped five rounds into .86 and .91 inch. For new, rack-grade ARs, this is unusually good accuracy.

The first load I tested in the Hardcore was Winchester's 69-grain Match. The best five-shot group fired at 100 yards yielded a .42-inch group, with an average of .68 inch. I measured the smallest group a couple of times to make sure I wasn't misreading my calipers.

Placing five shots into less than a half-inch at 100 yards is no easy feat, even for bolt-action rifles. I've been fortunate enough to accuracy test a lot of ARs, and I've only seen two other manufacturers get into the .4s; both cost about a thousand dollars more than this CORE 15 rifle. While initially surprised at the level of accuracy achieved with this Hardcore, I am genuinely excited about what CORE 15 has been able to accomplish. I love to see small companies do so well because both the company and the consumer win.


While the Hardcore loved Winchester's 69-grain Match load, it also did well with Black Hills' 52-grain Match ammunition. The best group fired with the Black Hills ammo measured .84 inch at 100 yards, with an average group size of 1.03 inches. Considering the 1:7 twist rate in the barrel, I wasn't surprised that the heavier load outperformed the lighter one.

The last ammunition tested was Hornady's 55-grain FMJ. I thought it would be beneficial to see how inexpensive range ammo would perform out of the rifle. The best group measured 1¼ inches, and the average was 1.43 inches.

CORE 15 made some decisive strategic moves bringing barrel production in-house while simultaneously investing in the machines and people to start making billet receivers. These decisions were risky because they were expensive and necessary for a new premium product line, and success was far from guaranteed. After a few hours on the range with the Hardcore, I'm happy to pronounce the effort a raging success. Congratulations, guys. Nice work!

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