The OBR (Optimized Battle Rifle) in 5.56 is LaRue's full-featured precision-grade AR-15 with a stainless match barrel, LaRue rail, and proprietary adjustable gas block, backed by a sub-half-MOA guarantee. Type: Rifle Action: Semi-Automatic Caliber: 5.56 NATO Capacity: 30 Year introduced: 2007, USA Weight: 96 oz Overall length: 36.5" Status: Active Intended use: Precision, Sport, Competition