I can't answer the question as to the how and why but several years ago I picked up an early S&W, 4" brl, round butt for a very good price. The seller told me the barrel was bulged but truthfully had he not told me I would have never known. I simply cannot tell and it has no effect on the shoot ability and accuracy. I bought it as a shooter and it has never failed me. Fun gun to shoot.

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Keep Shootin' and check 6