I have some older Hornady HP 250's, pre XTP, that have an exposed lead tip and have been loading those for my reduced 45 Colt @ 1,150 fps. They would likely shoot through a cat, but I'd bet they would work at slower velocities as well, as they are pretty soft up front. They have long been discontinued, but I have a couple boxes so can spare a few if ya wanna try them out. 8 grains of HS-6 should put them @ 800 fps + or -, similar to my 45 ACP defense load.

Your 300 will work fine. Go for the shoulder and break bones.