Since many of our targets are VERY old, continual pounding by round balls, most pure lead, but many of WW alloys in .60cal, lots of
the plates show damage. The damaged plates are mostly mild steel, some with eventual holes while others are simply bent or have chunks missing.
Many of these have been with us for close to 40years, though. They have been quite resilient, overall.
One target not quite that old, was a fairly long steel cylinder, 3/8" to 7/16" thick. Hanging inside, was a steel rod with a flat plate welded to it. A hit
on the outside of the cylinder would cause movement, which in turn cased the rod with plate to ring like a bell. Even the little .32 would make it ring
once. "ding"
My .69 would make it ring - ding-ga-ding-ga-ding for a full minute.
That one actually has a hole through the first layer of steel, facing the shooting line. Over time, the pounding takes it's toll, however slightly. There are a few
targets like this, but they still work.