Thanks guys, the bullet is a 220 gr MK from a .300 Wby. I will only shoot it at 100 yards. Oneone today said his cousin shot at one and the bullet came back and killed him. Then again he was shooting at rocks too.
I shot a 300 WinMag with factory 180gr CoreLokt bullets thru 3/4" mild steel plate at 100yds. I've also shot my 300 RUM with 190gr SMK's going 3200fps at 3/8" 500 brinell hardened steel plate at 300yds and but a tiny and I mean tiny dimple was all that happened.
For mild steel it seems very tough to me. We use it to build the base for tool grinders. I know that my friend and I were shooting a steel pipe coming out of the ground which was holding up a log downrange. It was a about 1/4 in both sides and with a .300 Winchester and a 150 grain hunting bullet it went through it like paper. Then again I don't know the strength of that pipe. I wold think that it will go through. A couple of people want to see it in a week and a half. I spray painted it bright red then used layout die to make a target on it. Looks pretty cool.
Do not shoot mild steel at 100 yds. Not only will chunks of bullet richochet, but chunks of steel will leave the surface of the target and occasionly travel back at the shooter at dangerous velocity. I have seen more than one Navy Seal pull steel splatter out of bleeding flesh on their legs and arms after engaging targets with steel in the background area from 30 to 100 meters.
Dave I think said a bunch, I've noticed the dimples protrusion on the steel noticably different with only slight changes of MV in the same load. It would be an interesting test to compare the same bullet at stepped up velocity increments to see where the dimple just starts to appear and then finally completely exits.
Doing this with several commonly used bullets around here on different levels of steel hardness would be a valuble reference. All you'd need to know then was the bullet, steel hardness and impact velocity to decide what range you needed to be at to keep from destroying the plate.
T-1 steel, I think someone said it was 300 brinell, the 165gn Sierra GK's I shot at it were at about 2600 fps and they made the slightest dimple at 100 yds, almost not noticable. My dads 300wsm with a 180 something put a hole right through it though. Interesting...