They tested this on Mythbusters.
They hung a man sized pig from a toggle that could easily be dislodged by a light push.
Then they shot it with various firearms. 9mms, .45, various submachine guns, rifles, etc. At one point three of them were shooting it with submachine guns simultaneously.
The only thing that dislodged it from the toggle was a 12ga shotgun. Even then, the slow mo didn't show it getting knocked back, it just got bumped enough for it to pretty much fall straight down.
They decided that too much energy was getting wasted by bullets going stright through the pig so they put a bullet proof vest on it and repeated the test.
Same results. Only the 12 ga dislodged it and it fell pretty much straight down--no significant movement backwards.
Amazing that experiments bear out what the mathematics and science predict, eh?
