As this post is showing,, the laws do vary state by state. I doubt there is a complied list of details. So,, if you are looking for details for hunting in certain states,, I'd get a copy of that state's current regs. And realize,, they can change yearly. Here in NC for years we had a minimum length for handguns & big game. It has changed,, along with the caliber restrictions. So,, to keep current,, check the most up to date printed material.
Now,, if your question was one to help you in a future hunting handgun purchase,, then,, I'd suggest something in about 6" or more to be legal in almost all places,, and a caliber starting with a 4.