It would be a wild guess but what the hell - maybe 1000 rounds?

I am thinking it's a bit soft based on how the rims of the craters push out - that metal is getting squished out & that can't happen if the metal is too brittle.
It is developing a crack & Jassenb's piece already cracked off a corner & his has seen less use.
I wonder if these are cast iron? anybody know a good test?
I saw some AR500 steel yesterday and the dents are way shallower and don't have the raised lip. But it does dent & will obviously fail eventually.
The truck spring material didn't raise a lip as much as this stuff does either.