ORC (Optics Ready Carbine) — Bushmaster's stripped-essentials carbine with a flat-top upper, six-position stock, and no iron sights, sold as a platform for buyers who planned to mount an optic from day one. A post-AWB budget-tier addition that undercut the standard XM15-E2S. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2006, United States Weight: 96 oz Overall length: 32.5" Status: Discontinued Intended use: Recreational Shooting, Home Defense