The Bullet Proof firing pin is a simple drop-in retrofit for shooters who want the toughest part available in their hard use gun. This part is a drop-in part for Series 70 or Series 80 style 1911 designs and for guns with a standard .45 ACP USGI/Colt diameter (.093) firing pin. *Note on 1911 firing pins- Most 1911 handguns on the market use one of three different diameters of firing pins. Standard .45 ACP/USGI 1911 is .093". Most Springfield Armory Pistols use .075". Current Production Wilson Combat 1911's of all calibers and many other brands uses a .38 Super/9mm pin regardless of caliber of .065 diameter.If the firing pin diameter needed is unknown, check the hole size in the recoil face or measure your pin diameter to determine the caliber firing pin needed for your slide before ordering.