Colt AR-15 "SP-1", .223 cal. semi-auto rifle. Serial #SP131316 mfg. 1973. Excellent condition. Nice early version of the Vietnam era M16 with triangular forearm, bayonet lug, no forward assist, hollow pistol grip, fixed buttstock, 20" skinny barrel. Excellent chrome bore, birdcage flash-hider and fixed carry handle. Finish is nice at 98%.  Triangular forearm. Missing magazine. These are becoming quite collectible and this one is super nice. A must have for your collection!