The Colt M4 OPS is a version of the M-16 machine gun issued to United States special forces operators. The Colt M4 OPS has an upper and lower receiver made of high quality aluminum and features a threaded muzzle, steel flash suppressor, bolt catch, CNC machined tactical railing with rail covers, functioning dust cover, adjustable telestock, as well as a removable tactical rear sight, rear sight adjustable for windage and elevation, and a front sight adjustable for elevation. Walther Colt M4 OPS .22lr 30rd 5760302