It's going to depend on how the gun is oriented to the body, and how powerful the given revolver is. With a .22 Short tight to the body and the shooting taking place in a nudist camp, I would be expecting nothing more than a little embedded gunpowder and a minor burn. With an Elmer Keith Memorial .44 Magnum handload and the barrel cylinder gap against the body, you could get a very severe flame cutting effect that could even open an eviscerating wound if that part of the body was right up against a morbidly obese shooter's abdomen.
When practicing retention shooting with the revolver, make sure the barrel-cylinder gap is ahead of the torso. To get an idea of flame cutting effect, buy a cheap piece of meat and drape it snugly over that part of the revolver, and fire into a safe backstop. Examine what it does to the meat.
Yours for caution,