That Ruger 10 has me salivating! I have no experience with the 10 mm auto cartridge but I have taken three whitetails with a cast swc in a .45 super which duplicates the velocity and KE of the 10mm with the same bullet weights. None were instant kills but none traveled more than 20 steps after the shot. My experience with light JHP's in the .44 mag has not been good as in lack of penetration on deer at high velocities but again, I have no experience with the 10 but it should be a very fine whitetail gun!