Rock River Arms, Inc. is a manufacturing company based in Colona, Illinois.

RRA manufactures firearms and parts and accessories for M1911 pistols and AR15/M16 type rifles in .223/5.56 & AR15 9mm. The company enjoys a solid reputation in the firearms industry. RRA was awarded a contract with the Drug Enforcement Administration to manufacture a new-issue AR15 carbine after they beat several high profile manufacturers in strenuous qualification testing.

The DEA subsequently purchased a substantial number of RRA carbines in 2003.

Rock River Arms is owned and operated by brothers Mark and Chuck Larson. Between them, the Larsons have almost half a century of gun making experience, with emphases on both semiautomatic pistols and gas operated self loading rifles. Indeed, the brothers' collective resume reads like a who's who of the American precision firearms industry: Between 1981 and 1991 the Larsons worked at Springfield Armory, Inc., where Mark was the head armorer. From Springfield Armory, the Larsons went into partnership with Les Baer to form Les Baer Custom, and produced some of the finest custom 1911 style pistols that have ever been seen on the US market. Parting ways with Les Baer in 1993, the Larsons began to build AR-15 type rifles for Eagle Arms in Coal Valley, Illinois. At around the same time, they began their own venture, Tolerance Plus (the name was later changed to Rock River Arms), producing custom 1911 pistols. The Larson brothers severed their connection with Eagle Arms in 1997 when that firm moved to Geneseo, Illinois. At the same time, Rock River Arms began to build AR-15 style rifles, with a commitment to producing the highest quality, most accurate AR's on the market.

Every major component of a Rock River AR15 starts out as either bar stock or a forging. Upper and lower receivers are made from forged and milled mil-spec 7075 T6 aluminum alloy that is then hard anodized to a surface hardness of 70 on the Rockwell scale. Lower receivers are held to extremely tight tolerances to ensure compatibility with the widest range of uppers possible. But that's just the start of the process. After final machining, each receiver is carefully polished to remove dings, scratches, and other small imperfections left over from the forging and milling processes. Once polished to a perfect mirror sheen, the receivers are then sandblasted and sent out for anodizing. This polishing step is unique, and is why minor receiver imperfections, such as those normally found in front of the magazine well, are not encountered on Rock River guns. Smaller parts, like the bolt stop, safety, and trigger components are investment castings made from 8620 steel that are case hardened to between 89 and 92 Rockwell.

Every Rock River Arms rifle features a 1:9" (1:8" in the DCM competition rifle) button rifled barrel made by Wilson Arms. All barrels are made from high grade chrome-moly steel. Each barrel is air gauged prior to assembly, and any that do not meet the most stringent criteria are rejected.

While the chambers of the rifle and the carbine that were the subject of this review were cut to SAAMI .223 Remington specifications, in the future all carbines will feature chambers cut to 5.56mm NATO specifications. After installation, the barrel's feed ramp is highly polished and contoured into the upper receiver, thus eliminating the common " step" between the barrel extension's feed ramp and the upper receiver that is found on most AR type rifles. As a result of these ministrations, Rock River Arms claims significantly improved reliability with all types of 5.56mm ammunition.