Wouldn’t the type of bullet also factor in?
I designed a machine to separate lead from chopped rubber backstops. I recovered 10,000 lbs of lead from one gun club. I’ve handled thousands of examples of pretty much anything that can occur during impacts. Some bullets just flatten out. Others disintegrate. Quite a few hit so hard they open into petals and the copper shell is empty. Some fuse together and actually appear to melt a bit.
We used to shoot steel targets. If the target was smallish the bullets would usually deflect downward. The bullets shatter on hitting heavy steel. Occasionally one will bounce back and even hit the shooter and make a bruise. About 10% of my recovered lead is as fine as sand and even flour.
It wouldn’t matter as they’re going to duck when you throw the gun at their head, anyway.
(I don’t remember which comedian that was from.)
That’s my theory regarding Superman. Clark Kent is bound to come in physical contact with people, and bumping into a shoulder that feels like a lead pipe in a suit would be startling.