Here are some 1/2" mild steel plates that I used for a penetration test a couple of years ago. They were placed one about a foot behind the other. Range was about 75 yards.
F= front plate, R= rear plate
1. 8mm Turk ball. Almost penetrated the front plate.
2. 8mm Italian AP. Easily blew through both plates.
3. 7.62X54R Chinese API. Penetrated the front plate, core broke in the rear plate.
4. 7.62X54R Russian API. Penetrated the front plate, core broke in the rear plate.