I have a berm about twice that size at our place, but don't have the impressive amount of steel you do. The chain hangers get abused at out range.
Have you fired ammo like .300 Win Mag at it?
So far .22, .223/5.56, 762x39, 762x54r (non steel core), 12g slugs and some pistol calibers. The 5.56 and 762 stuff does leave some small pits. But at 1/2" thick it's going to take quite a while to do any serious wear. They also are making a heckuva trench under the stand from the spalling.
Even the .22 makes a satisfying ring on the thick plates.
I really want to make the berm larger. Even though there are no buildings for at least a mile behind it.