Well, I went ahead and bought a 10" .223 on E-bay, and paid way too much for it. One other bidder just wouldn't quit. Now I have it, and it won't fit my frame!! I have an early (1969) pistol in the octagon .410/.45LC champering. The pistol is really nice with checkered walnut thumbrest grip. The new barrel won't open after it is installed( I have a 10" bull barrel forend for it).The new barrel and the original look slightly different on the mounting lug under the chamber. Also, the tang that protrudes under the chamber appears to be slightly wider on the new barrel. I, apparently mistakenly, thought the barrels were interchangeable. Is there a "rule' about dates of manufacture? Can the barrel be modified to fit? Does anyone need a real expensive barrel?!!