I have a comment to make that although I may be a little off topic, I think bears some thought regarding bulging of barrels near the muzzle. A few years ago I inspected an Italian (less common maker) 410 over/under that had about 47 thou of choke in one barrel---about double the normal full choke constriction ---my bore gauge would not fit into the muzzle! Although it bore Italian proof, I had a safety concern---I also had a concern how it would pattern. I declined to purchase it.