The crown is the rounded shape of the barrel at the muzzle. If the barrel was shortened, it would require being re-crowned. Also the diameter at the end would need machined down and a new slot cut to allow fitting of the front sight and key. - Bob
Hello Bob,
I just went with my Gunsmith to takedown that sight and he said that is a good Buba work.
BTW I cudnt find any marks on the base sight and in the back side sight.