Scooter1911
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Thanks for the info
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i have built a lot of custom revolvers over the years and measured a lot of factory barrels. On the factory guns, the amount of "crush fit" varies a good bit, but too much causes a lot of problems. I've seen ones that had the threaded part of the barrel squeezed down as much as .001 to .002 right ahead of the forcing cone.
How does the bore become restricted? Isn't the inside diameter of the frame and the outside diameter of the threaded part of the barrel the same?
How does the bore become restricted? Isn't the inside diameter of the frame and the outside diameter of the threaded part of the barrel the same?
I've never heard of an arbitrary torque specification on proper barrel to frame fit, at least from the factory reps or any of my instructors at the armorer's school or recert classes. The topic never came up, because barrel replacement was not something that normally fell within the scope of an armorer's duties or training......at least for me personally. We would just send the revolver back to the factory for any barrel work that was required.
I've installed and changed several barrels on my own S&W K and N frames over the years, and installed many aftermarket bull barrels on PPC revolvers I constructed. I always used an MGW brand frame wrench, and installed the barrels by "feel", and never thought about checking them for proper tightness with a torque wrench. To my knowledge, I've never had one shoot loose.
I'm not a machinist, but considering the thread size on the K-frame, for instance, at .540" X 36, 60 Ft. Lbs. seems like a lot of torque to place on the frame/barrel during installation. I know there are many talented machinists here on the forum who can comment on the 60 ft. lb. figure your gunsmith gave you, and give an opinion as to the proper specification.
I'm with WR, as I have no idea where the term "crush fit" originated, and how it applies to this type of installation. The barrel should stay put with or without a barrel pin if it is properly installed.
Check out the point at 2:30+ in this video at the S&W Performance center where the barrel is installed in the revolver. Very scientific. Padded vise, aluminum wrench, eyeball.