Introduced in 2012, ATI's Mil-Sport M4 Carbines became instant hits among customers looking for top quality AR-15 style rifles with forged aluminum receivers. Fine-tuned with many popular features, these American-made beauties perform flawlessly right out of the box at a price anyone can afford. The Mil-Sport M4 HD9 Carbine features a 9" Head Down KeyMod handguard that allows the rifle to be fitted by an enormous variety of aftermarket accessories. The 16" 4150cv M4 barrel is nitride treated and has a 1 in 9" twist. The buttstock is a Rogers Super-Stoc with six positions of adjustment. The rifle is optics-ready with a full-length Picatinny top-rail. The M4E1 upper receiver and the lower receiver are both constructed from 7015-T6 aluminum. A 30-round Magpul Pmag is included.