I like to think I know a bit about M29s. I've had them in 8 3/8, 6 1/2 and 6 inch barrels. Callahan uses a 6 1/2" in every movie but the last one, when a 6'' was used. He lost his gun in the bomb at the end of Magnum Force, and when it was kicked into the ocean near the end of Sudden Impact. By '88, when The Dead Pool came out S&W no longer made the 29 in 6 1/2'' so Harry took one with a 6''. All blue steel and all 6 1/2" till the last flick. And I'm tired of pointing this out...