David,
Can you give me the link to the 16g forum? I'm in the middle of relaying ribs on my Parker. Maybe I can pick up a tip or two.

I recall looking for shotgun barrels yrs ago when Brownells dropped them. I found an Italian manufacturing company that specialized in contract work and parts, including barrels. I wanna say the name was Emmbi or something like that. I did see some of their guns labeled with their name on rare occasion.

As to how many barrels are rejected for misalignment, I'll say probably none on production guns since they don't seem to check them and none on custom/bespoke guns because they straigten the tubes before starting and shoot and re-regulate until right, then finish the gun (watched that on the H&H video). On production guns, I've run across a few with barrels that were bent (curved) over their length bad enough that you could see it clearly and would print POI in two different places. It was a 3200 that I owned for about a day. Another was a Grulla sxs that had the barrels clearly swept upward so much that it shot like a trap gun. It went down the road from that owner. On a production gun, I'm willing to bet few shooters ever notice misalignment.