Thank you all for your input. I recognize the irreplaceable nature of the barrels on this gun and that is why I started with discussion instead of with an experiment. Particularly in light of the comment made by 2-piper about the 12 gauge wad in a 10 bore barrel opening enough to let these very hard shot scrub, this idea is dead.
I will use the inserts with lead target loads for practice, so as to become accustomed to shooting this gun. I believe the only non-lead fodder it will see will be Bismuth. Steel and the choke tubes marked steel will only be used in situations where I have failed to have the foresight to have proper ammo available, and then, only steel of moderate pressure.
