I used to carry a magnum handgun while hunting, but gave up on hauling the extra weight. I do sometimes carry one when bird hunting in pig country. Sometimes, while carrying a rifle, I will carry my .38 snubby with shotshells that I've loaded myself using the Speer capsules filled with #12 shot for snakes.
Like others have said, I feel there is little else that I can do with a handgun that I can't do with the rifle I am carrying, including finishing off wounded game.