Buffalo Bore loads their ammunition up to maximum SAAMI specifications, which delivers devastating performance on a wide range of game. These Heavy .45 Colt +P loads are safe in all LARGE FRAME Ruger revolvers.(includes Blackhawk, Super Blackhawk, all pre-2005 Vaquero, Bisley, Redhawk) These Heavy .45 Colt +P loads are NOT intended for the New Model Vaquero (small frame). These loads are also safe in all modern Model 1892 leverguns as well as all Winchester & Marlin 1894’s Please note that this ammunition is not intended for older guns. It is made for modern firearms only, as some of the ammunition could damage older and weaker firearms. This ammunition is new production, non-corrosive, in boxer primed, reloadable brass cases.