The new barrels fit fine on the older guns, except the ones with the tang that hangs down. I have a 715 and a 15, and a new 4"SS barrel that I swap around with an older 6" SS and a blued 4", that all shoot the same as other barrels the same length do. I really lucked out on that 4"SS barrel, the guy selling it must have thought the lead in it was pitting or something, it did look bad, but a couple of passes with a Lewis lead remover had it shining like new.