I've carried a Ruger Redhawk in 45 Colt with some bloody hot handloads for brown bear protection while working in the bush in Alaska. I've also carried the same chambered for the 500 Linebaugh. For some reason, I feel a little more comfortable with the Linebaugh chambering. Something to look into if you can use a .510 handgun chambering. If not, the 500 S&W round might work for you or the 475 Linebaugh. The problem with 500 S&W is the handgun is huge owing to the 1.6" cartridge length. The Linebaugh rounds will fit any Ruger Redhawk or Blackhawk type frame. The cylinder should be replaced with a 5 shot cylinder though.