Q. Can you safely shoot a .45 Auto Rim cartridge in a revolver chambered for a .45 Colt? A buddy of mine gave me some the cartridges, but I don’t have a gun in .45 Auto Rim. I do have a .45 Colt, though, and it looks like it should work.
A. I would not encourage anyone to attempt to fire a .45 Auto Rim cartridge in a cylinder chambered for .45 Colt. Aside from differences in the dimensions of the cartridge case, the Auto Rim round has a significantly thicker rim, approximately 0.090" versus approximately 0.060". This could certainly cause headspace and functioning problems. If the revolver in question is supplied with a separate cylinder specifically for the Auto Rim cartridge, there should be no problem. A number of firearm manufacturers have over the years offered .45 revolvers with dual cylinders, one for .45 Auto Rim or .45 ACP cartridges and one for .45 Colt.
Originally published September, 2006