This is a question I have been meaning to ask for some time. And, I admit up front, that I may not be using the correct terminology in calling it "crane flex". I have a few S&W revolvers and most of them do not allow the crane to flex out of the frame with reasonable finger pressure. I recently picked up a used 4-in M64, and the crane will flex out on it. It doesn't flex much - but it opens up enough to see a gap between the crane and frame.
This is one thing about S&W's that I have never figured out! At first, I thought it was from a bent extractor rod. But, I've rotated the (opened) cylinder over a steel ruler - and I cannot see any run-out of the extractor rod. Then, I thought - and there is little I can do about this - that maybe the ejector rod bore in the crane is to big. But, it doesn't have any more play in it than the revolvers that have near-zero crane flex.
I have even thought that maybe the crane might be sprung. But, I would think that this would impact cylinder rotation. That is, the cylinder would no longer be (near) perfectly square with the face of the barrel. The cylinder on the M64 rotates smoothly and the B/C gap does not appear to change throughout a full rotation.
Finally, the most obvious possibility (gotta love Occam's Razor!) is the ejector rod plunger, on the barrel, is out of tolerance or, maybe, has weak spring tension. I also understand, clearly, that this is a moot point as long as there isn't any lateral tension on the cylinder at the point of firing. But, it looks and feels sloppy and has bothered my for some time.
Can anyone weigh in on this? I'm not staying up at night worrying about this but it is something that bothers me... Thanks!!
This is one thing about S&W's that I have never figured out! At first, I thought it was from a bent extractor rod. But, I've rotated the (opened) cylinder over a steel ruler - and I cannot see any run-out of the extractor rod. Then, I thought - and there is little I can do about this - that maybe the ejector rod bore in the crane is to big. But, it doesn't have any more play in it than the revolvers that have near-zero crane flex.
I have even thought that maybe the crane might be sprung. But, I would think that this would impact cylinder rotation. That is, the cylinder would no longer be (near) perfectly square with the face of the barrel. The cylinder on the M64 rotates smoothly and the B/C gap does not appear to change throughout a full rotation.
Finally, the most obvious possibility (gotta love Occam's Razor!) is the ejector rod plunger, on the barrel, is out of tolerance or, maybe, has weak spring tension. I also understand, clearly, that this is a moot point as long as there isn't any lateral tension on the cylinder at the point of firing. But, it looks and feels sloppy and has bothered my for some time.
Can anyone weigh in on this? I'm not staying up at night worrying about this but it is something that bothers me... Thanks!!
The barrel/chamber alignment is near perfect - although all charge holes lock in a tiny bit (guessing 2/1000's) to one side with the hammer cocked. I have time on my hands so I put nickel-plated .38 cases into it and checked alignment with a flashlight - versus using a range rod. The bright front edges of the cases show up well - but, they're unfired so they may not be sitting exactly centered in the charge holes. It's otherwise a very nice revolver that's a couple of weeks away from a new-looking 3-inch barrel.
