.45 Colt. If you've got a Ruger or Thompson Contender, you can load them up to .44 mag. ballistics. Very versatile round that will run from 'bout 650 fps up to and over 1400 + fps. I now own two revolvers that caliber. I am currently looking for a Winchester Model 94 Trapper in .45 Colt (probably have a better chance winning the lottery!).