Kel-Tec's SU16 was designed from the ground up to be a lightweight AR15 alternative. This is the lightest gas piston-driven rifle on the market to date, weighing in at 4.7lbs unloaded. The lightweight is achieved by the polymers that Kel-Tec uses in the frame and furniture. This model has a built-in pistol grip and Kel-Tec's proprietary handguard that features a Picatinny rail on the underside for the mounting of grips and bipods. The SU16E utilizes a buffer tube so you can mount your favorite AR-15 stock or keep the adjustable one. - CALIBER .223 REM/ 5.56MM NATO - MAGAZINE (1) 10rd capacity PMAG - BARREL 16" 1:7" Twist, Threaded 28 x 1/2" - FURNITURE Kel-Tec polymer