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Buildsheet: The SnipAR Rifle

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This article originally appeared in RECOIL Issue 40

The theme of this issue being precision marksmanship, and the guns and gear that go with it, we felt it was only appropriate to build a reach-out-and-touch-something AR for this edition of build sheet. Specifically, we looked to the military’s SPR program for inspiration. The Special Purpose Rifle was a concept developed by Naval Surface Warfare Center Crane Division to fill a perceived gap in the ability of Special Operations troops to engage targets at long range. The idea was to find a weapon that could reach out beyond the range of a standard M4, or the shorter Mk 18 10.5-inch rifles, without the additional logistics of a full-blown 7.62mm sniper rifle.

The end result was a rifle known as the Mk12 — an AR variant with an 18-inch match barrel and a 3.5-10x scope, allowing a shooter to engage targets out to 600 meters while still using all the same mags, mag pouches, cleaning kit, and ancillaries associated with the M4. The use of heavier Mk 262 Mod 0 ammo enhanced ballistics at the receiving end of this equation.

The precision AR you see here was in no way intended to clone the original Mk12. Instead, we revisited the concept with newer components to assemble a gun that mirrors, or arguably exceeds the SPR’s capabilities. The heart of our build is a Rosco Manufacturing Purebreed barrel. Rosco Manufacturing has been behind the scenes for years, thriving on the OEM side of the barrel industry. Now they’re breaking out their own brand of barrels made completely in house. Their Purebreed line is dedicated to enhanced precision at extended ranges. All Purebreed barrels are made from 416R stainless, sporting 223 Wylde chambers and nickel boron barrel extensions. We used the 20-inch version with a rifle length gas system, and crowned with a SureFire muzzle brake. Rosco Manufacturing also produces full melonited BCGs, gas tubes, and gas blocks, which we also used in this build.

The barrel is nestled into an American Defense Manufacturing UIC billet receiver set. Their Universal Improved Carbine was designed from the ground up to be a fully ambidextrous rifle. The magazine release, bolt release, safety, and charging handle are all ambi, allowing an identical manual-of-arms regardless of which shoulder you fire from. The 15-inch M-LOK handguard is also of ADM origin. It’s industry-standard fare, providing three sides of M-LOK slots and a full-length top rail. The final ADM component on this rifle is the scope rings. Said scope rings secure a Vortex PST Gen II 3-15X. The PST uses Vortex’s illuminated EBR-2C MRAD reticle in the first focal plane, for accurate ranging at full magnification. The build was finished off with Magpul furniture and a Geissele trigger.

Of course, all these great components don’t mean much if they can’t work in harmony to produce the kinds of groups you’d expect out of a rifle meant for long-range work. To test this build we used Federal 77-grain ammo, which utilizes the same Sierra Match King bullet loaded into the original Mk 262 military ammo. Shooting from the prone off of a GG&G bipod, we were able to produce a group that looked somewhat like the Olympics symbol — that’s to say, three neatly punched interlocking bullet holes touching side-by-side from the 100-yard line. End to end, the group was a hair over a ½ inch. This, while shooting in the dirt in triple-digit heat, at the very end of a three-hour range session. While 15-power may be overkill for 100 yards, it allows more than enough leeway to reach out to the ragged edges of the .223 cartridge’s effective range.


The folks at Rosco have affectionately dubbed this build the #BarrelGang20 — based on their growing #BarrelGang Instagram tag. Whatever you want to call it, this rifle has demonstrated the potential to make head shots at a third of a mile. Whether you’re providing overwatch for an assault team, cleaning out a den of pesky prairie dogs, or shooting groups with your friends for beer and bragging rights, Rosco Manufacturing is showing some excellent potential for your high-precision barrel needs.

build sheet 40

Buildsheets: Past and Present

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