Angstadt Arms UDP-9, Semi-automatic, Short Barreled Rifle, 9MM, 6 Barrel, A2 Style Flash Hider, Anodized Finish, Black, 5.5 Free Float M-LOK Handguard, B5 Systems Bravo Stock, Manual Safety, 17 Rounds, 1 Magazine AAUDP09S06 The UDP-9 SBR is a compact, lightweight 9mm AR-15 short barrel rifle. It accepts 9mm double stack GLOCK magazine and features last round bolt hold open.