Like the company's original LAR-9 pistols, the new RRA LAR-9 A4 is constructed on a unique lower-receiver assembly, which is purpose-built to feed Colt SMG-style stick magazines without a cumbersome and awkward magwell-conversion block. Other caliber-specific features found in the lower receiver include a trigger-group spring and ejector designed to function reliably with 9mm rounds. The lower receiver is paired with Rock River Arms' 9mm-specific upper receiver, including a blowback bolt-carrier group, redesigned ejection-port cover and case deflector, all designed around the performance of the 9mm round.
Paired with this upper-and-lower receiver group is a chrome-moly barrel complete with a 1:10-inch twist rate. Barrels are available in either 7- or 10.5-inch lengths and are surrounded by the company's new, free-float handguard design, machined from aluminum and complete with M-Lok accessory-attachment slots. On guns with a 7-inch barrel, the handguard measures 6 inches long, while 10.5-inch barreled guns feature 9.25-inch long handguards. The barrels are topped with 1/2-36 TPI threaded muzzles and include an A2-style flash hider.
At the other end of the Rock River Arms LAR-9 A4 pistol is the new SB Tactical pistol-stabilizing brace. Consumers have a choice between the SBX-K brace or the newer SBA3 adjustable brace. Both braces offer enhanced stabilization of the pistols, enabling users to easily make more-precise, accurate shots at extended distances. Depending on barrel length, the LAR-9 A4 pistol measures 24.75 or 29.25 inches long, and the overall weight of the platform is 5.6 pounds. Other features found on the guns include a Hogue rubber pistol grip and a single-stage trigger.
Each RRA LAR-9 A4 pistol ships with one Colt SMG-style magazine. The suggested retail price on the guns starts at $980.