I have been making my own out of AR500. You can shoot 3/8 Ar500 with FMJ till you go bankrupt. It will also take steel core a long time to render AR500 useless but because of the cost of the AR500 I never shoot AP at them but everything else is fair game. I haven’t had a problem with 3/8 all the way up to 30-06 FMJ. Closest I have shot is 50 yards with the 06 FMJ and it just leaves a small dimple.
This is the one shot with M855 5.56 at 100 yards the rest are FMJ from .223, 243, 30-06 and a couple 12 ga slugs
5/8" T7 with M855 and two 300Win Mag(holes) at 100 yards, the shallower ones are from 200 yards