October 2006

9mm AR-Style Carbines: RockRiver, Bushmaster, and Olympic

The carbine offers greater accuracy and power than a handgun but is less clumsy to put into action than a ri?e. This makes the carbine especially handy when operating inside a building where walls and doorways limit movement and acquisition. Today's most popular carbines are built on the AR-15 platform, which normally shoots 5.56mm or .223 Remington ammo-ri?e cartridges. But we recently evaluated three AR-15-style carbines with 16-inch barrels chambered for 9mm ammunition--normally handgun fodder. They were the $1050 Bushmaster Carbon 15, the $1035 Rock River Arms CAR A4, and from Olympic Arms the $834 model K9.

Why 9mm? The manufacturers said the round's low cost and diminished penetration into walls were the main reasons. Two out of three reps said that civilian sales of 9mm carbines were higher than the total number sold to law enforcement, but the value of the 9mm carbine for training indoors is widely recognized. They also noted that the 9mm (0.355-inch diameter) bullet produced a larger wound canal in many instances than .223 Remington, the most common AR-15 round.

We decided to bench-test our carbines for accuracy at 50 yards using a Caldwell Tack Driver sandbag rest. Adding a scope of nearly any design would likely have improved our scores, but we shot all three weapons with open sights. For protection from the Texas sun, we set up beneath the covered benches of American Shooting Centers in HoustonĄ's George Bush Park (amshootcenters.com). We also decided to try shooting each carbine from a three-point prone position. Lying atop a Dillon Shooting Mat, ($65 from Dillon Precision, 800-762-3845), the long magazines played a part in support, along with the elbows. We wanted to know if pressing down on the long, thin 9mm magazines would affect reliability. Given that virtually all the 9mm ammunition we found was intended for use in a handgun, we went so far as to seek advice in choice of test ammunition from Rock River Arms, Olympic Arms and Bushmaster. All three recommended the 115-grain FMJ round. FederalĄ's American Eagle 115-grain FMJ ammunition was the only name speci?cally mentioned, so we started with this round. We also tested with 115-grain FMJ Match rounds from Atlanta Arms and Ammo (atlantaarmsandammo.com). Next we tried a 75-grain frangible training round from Precision Ammunition (precisionammo.com). PrecisionĄ's CM9 Matrix NTF featured a copper non-toxic bullet that was designed to disintegrate rather than penetrate or ricochet off of hard surfaces, making training at close range with steel targets and walls much safer. But with so many different types of 9mm ammunition to choose from, we decided to try three different types of expanding ammunition as well. We tested with FederalĄ's 105-grain expanding FMJ rounds, Black Hills 115-grain JHP remanufactured loads and SpeerĄ's 124 grain GDHP "Gold Dot" hollowpoints. The Gold Dots are among the most popular choice of professionals, so we wanted to see if it was viable to carry the same ammunition for pistol and carbine.

Here's what we found:

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