Reminds me of a story I heard about a friend of a friend (so grain of salt and all) who worked as security at a nuke plant. They've got a well-stocked armory and he liked to borrow guns to shoot with in his back yard.

He had brought a .50 cal rifle home and was shooting cans or something with a hill as a backdrop.

Then the cops showed up. Turns out the bullets were going through his targets (assuming he was hitting them), then passing right through the hill and hitting a house on the other side whose occupants called the police because they thought someone was shooting at them from the hill.

Not sure if anything came of it afterwards, though I remember he wasn't allowed to borrow guns from that armory anymore.

Okay, so if we are going to give batman flack for having super-alloys, where do we stand on Tony Stark putting a reactor in his chest with no concernable heat sink. (He wears it without the suit)

So many movies show people getting into gun battles indoors, and they will jump behind a couch or flip over a coffee table and take shelter from a hail of bullets, like that thin furniture is going to stop anything.

I recently watched Hunter-Killer, and one of the good guys was killed while swimming underwater and the bullets kept coming. They did it right at least in that sense

And notably, plates that do stop bullets often still only work once.

Also, among rifle calibers, .223/5.56 is quite weak on purpose. Many common rifles are far more powerful.

That last part is bullshit. If the force distributed across the plate were enough to break bones, then firing the rifle would dislocate the shoulder of the shooter.