T36C Pistol 5,56 cal. 9" Barrel Threaded 1/2x28 . Included G36 P-mag. This is a piston system and These are designed to run 556 Nato ammo and will not cycle properly with lighter .223 or steel cased ammo. The C set up does require the use of specific G36C QD's designed to clear the handgaurd if you plan to use a suppressor check for compatibility with you suppressor manufacturer.High back pressure suppressors may cause damage to the gas system. These are compatible with our pistol braces.