Would common steel or metal reinforced with iron withstand the impact of bullets?
Mostly steel wouldn’t as it is purposely malleable and ductile. Iron has possibilities especially wrought iron, when you make iron you make a very tough but brittle metal harder to work but a lot better to stop bullets than steel. It is possible by overquenching iron to make a metal impossible to drill, it wears the tip off a drill so if you want to cast the iron shape exactly into a mold then quench it from molten to solid rapidly you get an impenetrable metal. One inch thickness of such a metal will deflect bullets and just possibly be of some service now of course you want the thing to be able to move and to that aim a neodymium panel at the bottom could give maglev properties but if we open the issue of force shields we do a better composite and the military art of finding the jugular becomes harder and more technically challenging.
