Ring bulges I have experienced have been with certain older, maybe milder steels--one an old Ferlach gun. I am not an expert on the steel in his 60's era gun, just describing what I have seen. That ferlach drilling got them on both barrels just by shooting plastic wads according to one gunsmith here in Dallas (of course, it was pretty old). My Funk drilling shows a tiny bit from the high power slugs I tested in it...sad! Briley would tell you that if you hammer certain plain old screw in chokes enough with steel shot, there will be a measurable swell--special hardened choke tubes are supposed to help. Bridging shot is a danger there. Metallurgy in newer barrels has been adjusted for steel shot. And yet I had an old side lock Sauer drilling made in 1927 that was indestructible--there is no telling how many slugs I poured through it. So I could go either way with anecdotal examples. I was trying to be sensitive to his concern that just any old slug might not be the best idea with his tight chokes. But the biggest concern was that he start where he was on finding out what constriction was best for buckshot, and go methodically from there.
