I have a .45 Win mag. I use all .45 mag cases, but I do load some using .45 auto data. This gives me plinking rounds for my gun. By playing with bullet weight, I can get my handloads to shoot to about the same point of aim. I have heard I could shoot .45 auto ammo in my gun, but my way avoids all possibility of ringing the chamber. Because of the light powder load, I raise the barrel to vertical, then aim, to get the best accuracy.
mike