Drop-in conversion system replaces the top end of your Glock 20/21 pistol and converts it to fire the hard-hitting, yet controllable, 50 GI cartridge. Developed by Guncrafter, the 50 GI’s head is the same diameter as a .45 ACP, so the rest of your pistol remains stock, allowing easy conversion back to the original caliber. 50 GI ammo can be loaded to drive a 185 grain bullet at 1,200fps, with a felt recoil similar to 230 grain .45 ACP ball ammo. Delivers greater knock-down power, while remaining controllable during rapid fire. Conversion unit comes fully assembled with 4 1/2″ stainless steel barrel, firing pin, and guide rod with captive recoil spring. Slide and barrel are Mfg: Guncrafter SPECS: Slide/Barrel Assembly – Stainless steel, matte finish. Magazine Stainless steel liner, black polymer shell, base pad, and follower. 9-round capacity. May require some fitting of conversion unit’s locking lug and/or pistol’s locking block. Fits Glock 20/21 pistols only.