I picked up a piece of steel today label on it reads, hr carbon steel plate q&t400 brnll. Its 3/8. Lady said a guy ordered it for shooting and never picked it up so she gave it to me cheap. I'll be shooting it with a 7mm ultra at probably 800+. Will it be OK?????oh I think I can see a place on the label where it says ar400 too but its kind of rubbed off. Any help would be great.