If you're talking about deer hunting with a revolver, the heavy .357 is known to work. Most any .45 bullet of around 235 grains or more is known to work.
The key is a bullet with a large meplat.
Defense? Whichever handgun with which you can best hit a target when in a hurry and being stressed.
As for shooting skill in hunting, my belief is that the range should be limited to that distance at which one can reliably hit the end of a beer can.
You're from BATFE? Come right in! I use all your fine products!