The USMC variant of the M16A4 with Knights Armament RIS II handguard and ACOG optic. The primary USMC service rifle from 2000 through 2016 when the Corps began transitioning to the M4A1. Type: Semi-Auto Rifle Action: Gas-Operated Caliber: 5.56x45mm Capacity: 30 Year introduced: 1998, USA Weight: 8.9 oz Overall length: 40" Status: Active Military use: Yes Intended use: Military, Service Rifle