5.56 chambering. Comes with accessories but I will sell without them for $650. They include...Streamlight Light with pressure pad, Troy drop-in quad rail, Somogear Peq (IR and visible laser), Midwest Industries gas block rail (with QD points). This was a spare rifle for NV training and no longer need. Gun's iron sights are currently zeroed at 100 yards with M193. PEQ is a converging zero at 25 yards. LOCATED IN MCKINNEY