308 Socom 16.  Bought new and has not been fired since since I've owned it.  Bought it initially with locked mag, in Archangel chassis.   Changed chassis to Delta 14 (D14C) with Magpul SGA Moss 500 stock, purchased new from Delta 14 Chassis. Inc.,(see their website).  See all specs for rifle on Springfield Armory's website.  I have two 10 round magazines, on is a 20 round size locked for 10 rounds.