I'm building a target gun out of a 64-3. I threaded the Clark bull barrel into the frame and tried to close the cylinder. The flange at the front of the crane hits the bottom of the Clark barrel. I noticed that the stock barrel is relieved on the bottom to clear the crane flange. It seems to me that removing metal off the bottom of the barrel might weaken it, or at the very least be a worse idea than flattening the flange on the top of the crane.
Am I missing something? There would still be plenty of flange left on the front of the crane to secure it against then inside of the frame.
thanks,
-Armen

That flat spot at the six o'clock position of the barrel stub is for clearing the gas ring located on either the cylinder or the crane, depending on period of manufacture.

It would not be advisable to remove material on the crane or cylinder.

S&W machined the clearance spot on the barrel stub on these K frame guns to maintain maximum strength of the cylinder gas ring. Prior to the K frame magnums (M13, M19, M65, M66) the weakened barrel stub was not considered a problem until splitting of barrel forcing cones with extensive use of high intensity ammo became an issue.

For your target gun to be used with standard .38 Special ammunition, the barrel flat is not an issue.

Thanks for the advice. I'll relieve the bottom of the barrel as you advised.