“Rock River Arms LP2113 LAR-PDS 5.56 NATO 9″” 30+1 Alum Handguard Rubr Grip Blk The RRA LAR-PDS Pistol is the first of a generation of firearms employing RRA’s patent-pending Piston Driven System (PDS). Featuring a purpose-designed bolt carrier, an adjustable gas piston and an over-the-barrel spring and guide rod arrangement, the LAR-PDS is able to completely do away with the traditional recoil system associated with AR-style firearms, making for an extremely versatile weapon platform. The pistols feature an A2 flash hider and a muzzle threaded at .5-28, a folding, non-reciprocating ambidextrous charging handle, full-length top mounting rail, Tri-Rail handguard and the RRA two-stage trigger. The 9″” barrel is chrome moly with a 1:9″” twist.”