YSS The Rock River Arms LAR-15 is a family of AR-15-style rifles chambered in several calibers and offered with different barrel lengths and configurations. Exact specifications depend on the model. Common LAR-15 specifications Action: Semi-automatic Caliber: .223 Remington / 5.56 NATO, depending on barrel markings Barrel length: Commonly 16 inches Magazine capacity: Varies by magazine; commonly 30 rounds Overall length: Approximately 36 inches on a common 16-inch carbine Manufacturer: Rock River Arms