Years ago we had a bunch of 12 ga shells, not fit to hunt with so my bud said if we cut them they would be able to go thru a car rim. Well I said no way and cut the shell, well it went right thru that car wheel. Then a old timer I knew was a ww2 vet gave me some 30-06 steel core rounds, he said the ywere armour piercing. Well he was right they went right thru car engines, plate steel etc.
So one day about 15 years later my cuzz shows up wit hsome rail road tie, this stuff is very heavy steel, we cut a shell and shot it, looked like the steel plate you shot. Didnt go thru but made a hole like that one.