If you somehow shoot a gun hard enough to knock it out of someone's hands, then at minimum, you're breaking all the bones in that hand and bruising all the muscles that were holding onto the gun. Most likely scenario, at least one finger is getting severed/wrecked by the impact. Worst case scenario (for the target), you hit the gun and/or hand in such a way that the wrist gets bent beyond what it can handle, breaking the bones there (if not outright tearing the skin/muscle and largely severing the target's hand).

Force from a bullet takes a little more time/distance to dissipate than depicted in Hollywood, and the human body can be more fragile than it appears some times.

If you somehow shoot a gun hard enough to knock it out of someone's hands, then at minimum, you're breaking all the bones in that hand and bruising all the muscles that were holding onto the gun. Most likely scenario, at least one finger is getting severed/wrecked by the impact. Worst case scenario (for the target), you hit the gun and/or hand in such a way that the wrist gets bent beyond what it can handle, breaking the bones there (if not outright tearing the skin/muscle and largely severing the target's hand).

Force from a bullet takes a little more time/distance to dissipate than depicted in Hollywood, and the human body can more fragile than it appears some times.