I really don't think with pins it was richochets... I think it is off center hits with SLOW 45 bullets that cause the pin to start to rotate, and it exits the "back" of the pin but "facing" you. At least thats what we concluded as it happened a few times with new pins, first shot, only one shot in the pin, and it had both entrance and exit, but pretty far off center line....
The steel pretty much splatters most lead bullets in plates is why thats pretty safe.
