Rifleman Review: Rock River Arms LAR-15M .17 HMR

 Building a reliable semi-automatic rifle chambered for the .17 HMR can be a challenge, but Rock River Arms seems to have solved the issue with its unique RRA .17 HMR AR-style rifle. Watch our "American Rifleman Television" Rifleman Review segment above to see the details of how this rifle works.

"So this week on Rifleman Review, we're taking a look at a Rock River Arms RRA .17 HMR semi-automatic rifle," American Rifleman Managing Editor Christopher Olsen said. "Now this gun is patterned after the company's rimfire offerings that we've seen before. They do have a National Match version, so if you need a trainer, you've got one in .22 Long Rifle. There's a few other variants, too, but now they've got the .17 HMR."

In terms of overall construction, the RRA .17 HMR is built like many other AR-style rifles on the market, with a six-position adjustable Magpul SKL stock, a two piece receiver design like that of the AR-15 and a full-length, M-Lok handguard that provides plenty of room for accessories.

" But what really gets interesting is what's inside of this gun and how this gun works," Olsen said. "So with a Rock River RRA .17 HMR, you get a pretty unique gas system. It is gas operated, but it's also delayed blowback. So you get that direct impingement like you get on a standard AR where gas is going rearward, but there's a ball detent mounted inside of the upper receiver that is designed to hold the bolt just temporarily to reduce some of the pressure in the barrel before clearing it and going rearward."

The benefit of this operating system is that it offers reliable operation within a certain range of .17 HMR ammo offerings, notably with bullet weights ranging from 15.5 to 20 grains. The rifle ships with a 10-round detachable polymer magazine with a translucent body.

 "So Rock River's built quite a reputation with its rifles and pistols, but this .17 HMR version is quite a new entrant that we've not seen before from the company," Olsen said. "And if .17 HMR is a cartridge that you are into, this might be your next great rifle."

Rock River Arms LAR-15M .17 HMR Specifications
Manufacturer: Rock River Arms
Action Type: gas-operated, semi-automatic, rimfire rifle
Chambering: .17 HMR
Lower Receiver: forged RRA LAR-15M
Upper Receiver: billet aluminum; RRA A4
Barrel: 18" 41V50 chrome-moly steel
Magazine: 10-round detachable box
Sights: none, Picatinny rail
Handguard: 15" lightweight aluminum; M-Lok compatible
Grip: Magpul MOE
Stock: six-position adjustable Magpul MOE SL-K
Trigger: two-stage, NM Ultra Match
Overall Length: 33.5" (collapsed)
Weight: 6 lbs., 12 ozs.
Accessories: owner's manual, lock
MSRP: $1,190

To watch complete segments of past episodes of American Rifleman TV, go to americanrifleman.org/videos/artv/. For all-new episodes of ARTV, tune in Wednesday nights to Outdoor Channel 8:30 p.m. and 11:30 p.m. EST.