Remember Newton's laws, the one that says that for every action there's an equal and opposite reaction. The force that the bullet applies to the target is never going to be any greater than the recoil force that the gun has. So, if shooting the gun does not knock you off of your feet, the bullet isn't going to knock the adversary off of his feet, either.
Now, I've been knocked flat by a shotgun's recoil -- first time I shot one when I was 12. That proves that a shotgun actually can do it. But that's a shotgun, a different animal than a handgun.