He asked if there was an alternative to steel safe for his gun and I offered one...sheesh. If he'd of asked if there was a way to shoot steel from his gun, I would have answered as Ben did. You really need to pause a moment before jumping all over everything I post and read the original question. It is getting a bit tiresome.....you shotgun geeks really are a different bunch.
I agree that Ben has a way better idea too but a question was asked and I answered it.......

Maybe try picking your nose instead of at everything I post.

BTW, bismuth is readily available once again. Pinnacle Ammunition is loading it using the same components as Bismuth Cartridge. But I'm sure an expert like yourself was well aware of that.