7.62X39 Rifle Kits AR-15 4140 Chrome Moly Steel HBAR barrel attached to mil-spec upper, with rifle and Carbine length handguards. This kit comes with your choice of A-2 or standard flat-top upper, includes lower parts kit, and your choice of A-2 Buttstock or M-4 Style 6 Position buttstock. this Rifle Kit has a 1x10 twist, 4140 chrome moly barrel with a 1/2x36 TPI Flash Hider. This AR-15 Rifle kit is headspaced, and ready to mount to your lower receiver. Once you have an assembled lower with the parts provided in the kit, and mount the upper, this is an operational firearm in 7.62 X 39 Cal.