Ultimate Arms Gear .22 Caliber Internal Interbore Pistol Revolver Handgun Chamber Barrel Bore Borelock Muzzle Security Safety Key Lock for .22LR .22 Long Rifle Fits 4 3/4 " - 6 1/4" Revolver Barrel Length & 5 3/4" - 7 1/4" Auto Pistol Barrel Length