The more I look at this old revolver, the more I wonder about it. The finish looks like typical military phosphate, and there are no import marks. It appears not to have been fired since the refinish, which if it coincides with the FTR, was 60 years ago. Perhaps I was deceived by the appearance. But with no turn line on the cylinder, no loss of finish on the recoil plate, nice lock up, I did not expect that the cylinder would bind when I tried to fire it. Measuring the rim thickness of the brass, the Winchester nickel cases measured .056 while the Starline brass miked at .058, it was pretty obvious why cylinder did not want to turn and the trigger pull increased to where you wondered if that's what the 3-1/2 tons stamped on the frame meant. So when fitting and repairing these revolvers, how did the Brits ensure the cylinder was properly positioned to have the correct clearances? Was it all supposed to be controlled by the Cylinder Retaining Cam? Likely whoever stuck that shim in there did not use proving dummies or try to fire it.