Lets clarify a few things :
We talking modern rifles like Winchester model 92 or 94 .
Handloads not limited to 45 Colt black powder low pressure loads .
Not limited to factory ammo but using ammo we handload .
If yes ... Then 45 Colt !
Bullet of choice - Lyman #454424 - 255 gr. SWC
Being a graduate of the Elmer Keith school of thought ...
A big heavy slug will kill deer better than a smaller lighter faster one .
Gary