Hooch........you're kind of new to the game, aren't you? Now you're going to hear it from two barrel makers. Hugh and I.
Put a little pipe dope on the threads, makes em' go in nice and easy. What is your concern about the barrel? Are you afraid
it will blow out on one side, or, maybe leak some gas back thru the threads.....I doubt it. Just screw that plug back in and build
your gun, no problem. You have a plug that measures .750 diameter on the outside, which has been fit into a barrel with a
bore about .665, not a whole lot but enough. You run into these situations a lot in those big bores. Bear in mind, the pressures in a big smoothbore are a lot less than a 50 cal. rifle. Honestly, I don't really see any problem with using this barrel.
I'm not positive of this but if you bought a 16 ga. barrel from another company, you might get the same thread size.....Don