Originating in 1957, the .454 Casull is one of the most powerful revolver cartridges available today. This is basically a magnum version of the .45 Colt. It has been lengthened by .100" so it can't be fired in a .45 Colt firearm, though .45 Colt can be fired safely in a .454 Casull. Gun systems are available from Freedom Arms, Taurus, Ruger, Magnum Research, and Thompson/Center.