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Alexander Arms .17 HMR AR-15

Alexander Arms makes the king of rimfires not only AR compatible but also insanely enjoyable.

Alexander Arms .17 HMR AR-15
Photos By Mark Fingar 

When the .17 Hornady Magnum Rimfire (HMR) was launched in 2002, it rocked the shooting world. Obscenely accurate, affordable, flat-shooting and lethal on even coyote-sized game, the little cartridge made believers out of anyone who used one. While it’ll never pass the .22LR in popularity or the .17 WSM in performance, when it comes to balancing cartridge capabilities with gun/ammo availability, the HMR is the king of the rimfire world.

Because of its success, a plethora of firearms have been offered in .17 HMR. The vast majority are bolt actions due to the difficulties in getting a semiauto to run reliably. Luckily, the geniuses at Alexander Arms — creators of the 6.5 Grendel and .50 Beowulf — figured that out years ago. The Radford, Virginia, company now offers complete AR rifles, pistols and upgrade kits to allow homebuilders to merge the mighty .17 HMR with the most versatile firearm system ever designed.

According to Alexander Arms’ Wayne Holt, who was at Hornady during the time of the cartridge launch, the key to Alexander Arms’ success was beginning with a standard AR-15 platform in the first place.

Alexander Arms .17 HMR AR
The dimensions of an AR allowed Alexander Arms the room to create the magazines and inner parts that makes the .17 HMR work flawlessly.

“During my time at Hornady, I bought every semiautomatic .17 HMR that came out,” said Holt. “None of them worked perfectly. Instead of shoehorning the .17 HMR into an existing rimfire design, Alexander Arms started with an AR platform, giving them all the space necessary to build and fit custom components to reliably run the firearm.”


Key Differences

Holt explained that while the .17 HMR feels and functions like an AR-15 should, there are a few key differences in the design. These include the bolt carrier, buffer system and magazine.


Standard centerfire ARs use high-pressure gas to unlock the bolt and cycle the firearm. Due to the .17 HMR’s smaller size and lack of pressure, the rifle works using a simple blowback operation. Size wise, the bolt carrier is similar to the standard 5.56 carrier, but since it eliminates the rotating bolt of a direct-impingement system, the bolt face is integral with the carrier. Its weight, along with a unique buffer modeled on a standard AR buffer, is precisely balanced to properly regulate the cycling. Because of the proprietary bolt carrier, the barrel extension was also modified to accept rounds from a detachable 10-round magazine.

Alexander Arms .17 HMR AR
The blowback design eliminates the rotating bolt while integrating the bolt face with the carrier.

Constructed of polymer and made by Alexander Arms in-house, the magazine cycles rounds exactly as it should. As an added bonus, spare mags cost only $11.54, making them the best bargain in the magazine world. According to Holt, the magazine design has always worked, but they did tweak the material’s properties a bit early on.

“Bill Alexander designed the magazine, and it went through several iterations,” said Holt. “Ultimately, he went with a new polymer because cleaning solvents could deteriorate the polymer walls. Since that change, there’s been no other issues.”

Alexander Arms .17 HMR AR

According to Holt, these little .17s run and run, and they shoot just as accurately as a bolt-action design.




“With my personal Alexander Arms .17 HMR, I can’t remember the last time I had it jam,” said Holt. “It runs like a clock. In fact, my kids nearly wiped out every small animal on our family farm with that .17 HMR. It works flawlessly. As for accuracy, I have not noticed any tradeoffs compared to a bolt action.”

Multiple Options

Shooters interested in a .17 HMR AR-15 have multiple options. The most common is the rifle version, which uses an 18-inch barrel with a 1:9-inch twist rate. For high-volume rodent assassins or target shooters, this may be the best option. It’s affordable to feed and possesses almost no recoil, making it ideal for shooters of all ages. Prices on complete rifles range from $1,096 up to $1,674.

Alexander Arms .17 HMR AR

The most unique option is their new Highlander pistol. Featuring an 11-inch barrel with a 1:10-inch twist, the pistol is compact, easy to store and makes a great suppressor host. Due to the small amount of propellant in a .17 HMR case, the shorter barrel doesn’t lose much velocity. Price for the Highlander pistol is $1,659.


Alexander Arms .17 HMR AR
The .17 HMR rifle (left) features an 18-inch barrel while the Highlander pistol uses an 11-inch barrel.

In addition to complete firearms, Alexander Arms offers uppers that snap onto your favorite lower as well as all the accessories needed to build your own .17 HMR AR. While assembling a .17 HMR AR takes a bit more work than a standard 5.56, experienced builders shouldn’t have much difficulty. Plus, this option enables a firearm built to your exact specs.

Over the past decade, the AR-15 has seen an explosion in interest and innovation. From dedicated .22LRs to a plethora of centerfire cartridges designed to operate within the confines of the AR magazine, the options are nearly limitless — with one exception. If you’re after a .17 HMR that runs reliably and produces accuracy on par with the bolt actions, Alexander Arms is still the only option.

For fans of the AR-15 and the .17 HMR, it’s not a match made in heaven; it’s a match made possible by tireless design and tinkering in Radford, Virginia.


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