Those rounds will go straight through a human body, straight through a brick wall, and still be lethal.

This is incorrect. The 5.56 / .223 cartridge is not like in the movies. The nose of the bullet deforms on impact by design.

There are precious few cartridges that will “go through a brick wall”. There are even fewer that would be lethal on the other side of that wall.

My thought is that these rifles have no business being leveraged for this application.