In my experience if you are shooting at it with rifles it needs to be 400 plus, the brand ie hardox/biz/G450/G500/AR500 is all but Irrelevant.
You NEED 400 plus but no more than that, biz has got a bad name in some circles because of biz80, which is a high strength steel....it is not hard/can easily be drilled and will be cut up by high velocity bullets and was never designed as a high impact/wear steel..... that is 400 also conveniently called "Biz" or Bisalloy