How thick was that cutting edge? daaaamn!
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...