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Review: Rock River Arms ATH V2

Review: Rock River Arms ATH V2

Photos by Mark Fingar

Several years ago, I was visiting with a good friend of mine when the discussion turned to the guns he carried on duty.. He was an agent with the Diplomatic Security Service (DSS) and a member of their tactical team. He fired tens of thousands of rounds each year, which made me curious about what firearms he used and how they fared.

The rifles they were issued were manufactured by Rock River Arms, and were carbine variants in similar spec to the U.S. military’s M4. My buddy had a significant amount of experience on several of them, so I value his opinion of the platform.

He loved his Rock River rifle. When asked about maintenance, he responded with, “I like to shoot it, but I let the armorer take care of it.” Each rifle he was issued was carried for about a year and typically saw 20,000 rounds before replacement with a new one. He had nothing but respect for those Rock River rifles.

The New Kid 

My experience with Rock River AR-­pattern rifles hasn’t involved round counts like my friend’s, but they’ve been just as positive. I have yet to find a Rock River rifle that wasn’t extremely accurate, so it’s only natural to have a favorable impression of the brand.

A subtle mark on the upper receiver indicates the manufacturer. This one features a square shape that tells us it was made by Brass Aluminum Forging Enterprises in Michigan.

A big reason that these rifles shoot so well is the barrel. The barrels Rock River use come from the Connecticut-­based company, Wilson Arms ( Wilson makes the barrel, contours it and starts the chambering process. Once the barrels get to Colona, Illinois, Rock River finishes the chambering job and then cryogenically stress-­relieves the barrel before mating it to an upper receiver.

The tight adherence to exacting tolerances of their chamber dimensions and the stress-­relieving effort are two of the big contributors that I credit for this brand’s reputation for accuracy. This attention to accuracy is especially evident in Rock River’s new model, the Advanced Tactical Hunter V2 (ATH V2).

The ATH V2 comes with an 18-­inch, stainless steel, heavy match barrel. The rifle I tested was chambered in .223 Wylde, meaning that it can shoot both .223 Remington and 5.56x45mm (NATO) ammunition.

The lower receiver is a standard LAR-15 model. It features a magazine well that’s slightly beveled to accept most AR-15 pattern magazines.

The .223 Wylde chamber has a tight .224-­inch freebore that keeps bullets — especially long 69-­ and 77-­grain types — from yawing in the chamber prior to engaging the rifling. If a bullet enters the rifling crooked, accuracy will always suffer. The Wylde chamber and tight freebore prevent that from occurring. Since the freebore area only surrounds the bullet when a cartridge is chambered, variation in brass thickness causes no trouble.

The deep-­freeze cryogenic process that each barrel receives removes any stress imparted on it during the manufacturing process. I know several manufacturers that swear by the process and they all turn out highly accurate rifles, so there is something to be said for the treatment.

Putting a barrel through the cryogenic process at Rock River means the barrel is cooled down in steps until it reaches 300 degrees Fahrenheit below zero. At each temperature step, Rock River will let the barrels soak at that temp for a specific period of time.



Once they hit 300 below zero, they’ll bring the barrels up (also in steps) to 200 degrees above zero. Metallurgists indicate that the extreme temperatures eliminate the stress imparted on the metal from cutting the chamber and contouring the barrel profile. At those temperatures, the molecules align with their neighbors. This eliminates all stress risers in the barrel that can cause a barrel to shift point of impact as it heats when shot.

The 18-­inch barrel that Rock River chose to install has a 1:8-­inch twist and features a mid-­length gas system. The gas block has two setscrews that hold it in place, and the contour is Rock River’s “heavy match.” Far from what you’d call a heavy match barrel on a bolt-­action rifle, the barrel on the ATH V2 has almost a straight contour and measures three-­quarters of an inch at the muzzle.

Rock River sells many styles of muzzle devices, and includes its RRA Tactical Muzzle Brake with the new ATH V2. It’s very effective while adding 2 inches in length and 3.1 ounces of weight.

The combination of barrel weight, the proprietary process used to manufacture the barrel and the mid-­length gas system makes for one of the lightest recoiling and most accurate AR-­pattern rifles I’ve tested. Rock River has also correctly set up the gas system where the rifle is neither under-­ or over-­gassed. For me, all cases extracted and landed at about 4 o’clock relative to the muzzle.

The Package 

The rest of the ATH V2 compliments the barrel work. The rifle follows the AR-­pattern designed by Eugene Stoner and Jim Sullivan very closely. It’s a direct-­impingement (DI) rifle manufactured to all the standard dimensions.


While the location and function of the trigger is identical to what Stoner and Sullivan originally specified, Rock River includes a two-­stage trigger of their design, which is superior to the standard semiautomatic trigger found in most ARs. Rock River’s trigger has a lighter 3½-­pound pull weight and a very crisp let-­off. It’s much easier to shoot with this trigger than with a standard variant.

Rock River Arms has been making their two-­stage match trigger for more than a decade. The first time I bought one was in 2006 when one of my Special Forces’ teammates built an AR-­15 for me.

The Assault Weapon’s Ban had sunset and I wanted a really nice AR. My teammate, SFC Tung Nguyen, was a hardcore competitive shooter and offered to build me exactly what I wanted. He pointed out how good the Rock River trigger was, so I’ve had it in that rifle ever since. Sadly, Nguyen was killed in action in Iraq later that year, so the rifle is particularly special to me and will always remain in my possession.

Everything about the ATH V2 suggests accuracy including its hammer designed by Rock River. With more mass near the trigger pin, less disturbance is generated to harm accuracy.

Rock River’s triggers not only have a lighter pull weight and crisper let-­off, the hammer shape promotes excellent accuracy. In comparison, the standard AR trigger has most of its mass as far away as possible from the pin about which it rotates. This gives the hammer considerable inertia. All that inertia transfers to the back of the bolt carrier when the hammer slams home. Take any AR with this trigger and watch what happens to the crosshairs of a magnified optic during dry fire. The crosshairs bounce all over the place.

The hammer in Rock River’s trigger moves most of the mass to a location much closer to the trigger pin. This allows the hammer to move faster (once released) and still get positive ignition of the cartridge without generating a ton of reticle disturbance. There is a reason almost all of the so-­called “match” triggers available today have a hammer shape very similar to the one found on this Rock River. Rock River started this trend long before it became mainstream. The accuracy increase gained by this hammer profile makes every other hammer shape irrelevant.

Instead of compromising its historical success, Rock River installed a mid-­length gas block that produced consistent cycling. It is low profile and visible through open M-Lok slots.

The handguard on the ATH V2 is ideal for a general-­use rifle. It is 11 inches long, so it covers the mid-­length gas system and has sections of M-­Lok cut into the sides and bottom. This handguard is very comfortable in the hand while still leaving plenty of attachment options for any accessories the shooter might want to employ.

The winter triggerguard not only allows for a gloved finger, it also closes the gap between the guard and grip that was notorious for tearing skin off knuckles.

Rock River cured a couple other standard AR failings with parts they developed in-­house. One I especially like is the winter triggerguard; it’s oversized and creates an opening large enough for a gloved finger. But the best feature is the way it eliminates the gap normally found where the grip’s frontstrap meets the triggerguard. Usually, there is about a ¼-­inch gap that will shred the knuckle of the shooter’s middle finger if they fire a couple hundred rounds (or more) in a day. Rock River’s winter triggerguard solves this problem.

The company has created a unique, so-called “Star” safety selector switch that is both fast and positive. A normal throw lever found on an AR works fine for a right-­handed shooter firing off the right shoulder. However, the standard selector lever can be a struggle when a right-­handed shooter moves the rifle to the left shoulder and tries to work the selector with the index finger. Not everyone likes to shoot off both shoulders, but those who do are familiar with how difficult the selector struggle is.

To improve usability of the selector switch by the left index finger when used on the left shoulder, a small extension was added.

To fix this issue, Rock River has given its Star selector a nipple that sits at the end of the lever, and it protrudes away from the receiver. The increased profile of the unit makes it easy to locate, engage and manipulate with the left hand’s index finger when firing off the left shoulder. We should all get a little more practice shooting off our weak shoulder. The Rock River Star selector makes that process more intuitive and does it without the expense of purchasing an ambidextrous switch.

At The Range 


Performance of Rock River’s new ATH V2 was exceptional. This is not the first time I’ve tested a Rock River rifle with their stainless-­steel match barrel, so I was not surprised when group averages hovered near ¾ MOA for five shots at 100 yards. Contrary to what you’ll find on the internet, most rifles are not capable of this kind of performance with factory ammunition.

While I was pleased to see the new rifle perform well, I like to know all the reasons why. The barrel and trigger are certainly the two greatest contributors to the V2’s accuracy, but Rock River gets the small things right that most others miss.

The forend on the ATH V2 was manufactured for Rock River Arms by Midwest Industries (MI), a popular supplier of AR-15 products. It is a free-float model that securely locks to the upper receiver.

An important accuracy check you can run on any AR without even firing the rifle is to separate the receivers and remove the charging handle and bolt. Place just the bolt carrier back in the upper receiver and slide it into battery while observing the short section of gas tube that comes into the upper receiver.

Rock River Arms properly stakes the gas key to the bolt carrier. Building on a reputation for offering quality components, Rock River also sells complete chromed bolt carrier groups.

If that gas tube moves when the bolt carrier comes forward, the carrier key is hitting the gas tube. This will cause the occasional flyer when shooting groups because the other end of that gas tube is attached directly to the barrel. When the carrier key hits the gas tube, that disturbance travels down the tube and into the barrel. It’s like tapping the barrel with a hammer between shots, but the folks at Rock River obviously found a consistent way to avoid this from happening in the V2 during its assembly process.

Notes: Accuracy is the average of five, five-shot groups at 100 yards from a rest. Velocity is the average of 10 shots recorded by a LabRadar chronograph adjacent to the muzzle.

Rock River has been around for a long time and they maintain a devoted following because they continue to use quality components while giving attention to the details. The ATH V2 will continue that proud tradition. 

Rock River Arms ATH V2
Type: Gas operated, direct impingement, semiautomatic
Cartridge: .223 Wylde
Capacity: 20 or 30 rds.
Barrel: 18 in., 1:8-in. twist, stainless steel
Overall Length: 36.5 in.
Weight: 7 lbs., 14 oz.
Stock: Rock River Operator A2
Grip: Ergo Suregrip
Length of Pull: 13.5 in.
Finish: Type III, hard coat, anodized
Trigger: RRA Match
Sights: Adjustable, flip-up
Safety: Selector, two position
MSRP: $1,370
Manufacturer: Rock River Arms,

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