I have pondered this as well, so as said the standard 45 auto is pretty slow moving. I have never used 45 auto or 45 colt for hunting but i have a Ruger convertible and it got me thinking, 45 acp is real similar to 45 colt cowboy loads, so many people say 45 acp is ok for hunting close range but i have seen many people say 45 colt cowboy loads are not. So what would be the difference? Say 230 grain at 800fps VS 250 grain at 800fps? I am not bashing either, i use a 44 mag with 240 grain SWC's at 1100fps for hunting, but the 45 colt is just plain fun to shoot.