I don't know if the rim will work in a 45 ACP revolver, but I started using 5 in 1 blank cases from Starline to make shotshells. I size them in a 38-40 die so they'll fit anything I own, from 44-40 to 44 Special to 45 Colt. They are already the correct length and easy to stuff with whatever shot size is desired. I compared weight to a plastic 44 Speer capsule and the 5 in 1 will hold a few more pellets but it's not a huge difference. The most important thing to me is that the brass cases are much more robust than the Speer capsules. 4-5 grains of a fast pistol powder gives enough ooomph to kill snakes and birds up close.