I have given this subject of steel shot in older guns some thought and I conclude a ammo maker or wad maker could indeed create a wad that would allow this to be done with little chance of harm to twentieth century shotgun. As already pointed out the pressure can be made appropriate so the problem of steel shot through the choke remains the problem. A 12 gauge bore is around .729 and the full choke restriction is .040 or a diameter of .689. A 16 gauge bore is .662 that is less than the full choke constriction of the 12 so by designing a wad for a 12ga with a 16 shot column size, has the shot missing the choke by .067 or about the diameter of a piece of 8 shot. Now a problem may arrive with the shot shifting rearward and this causing some exspansion and rigidity, again creating some possibilty that bridging could occur exceed the .067 cushion, so perhaps a countering plastic crusher could be employed to reduce the bridge effect. The result might be a 12ga with full choke throwing 16ga cylinder patterns but if I could keep shooting my old guns for grouse, woodcock, dove and skeet I'd learn to live with it. I will point out the our Pennsylvania Game Commision loses hunters and license sales, every time the price rises even though some point out how reasonable the price remains. The PGC is running a deficit an is scrambling to figure out how to keep people hunting. It is always concluded that since fewer licenses are sold the price must be increased. This works with products like shotshells too. The fewer who want them the fewer are made and the price goes higher. I would use Bismuth or whatever to keep shooting my Fox in the grouse woods, but the preseason practice shooting would be a killer. If I buy another gun for the practice I might as well use it for the grouse. I hope the shell manufacturers are working on those wads.