Had a similar discussion about checking end shake on another thread, and while checking with feeler gauges l noticed that it was going in fine at first but not making it out the other side. On the bottom of the cylinder it was fine but not at the top. After some discussion about the firing pin driving the cylinder forward was the time to check the gap, that’s when l noticed the gap difference top and bottom. My take is shims and possibly the retention bushing at the rear, where the extractor comes out. The bushing has four tabs that the yoke snaps into. Over the years l disassembled it to inspect and lubricate. Now l realized maybe l did it to much and weakened the bushing tabs and it no longer supports the yoke like it should?
Wondering if it would affect accuracy.. bullet alignment to effect barrel harmonics? Guess there’s no real way to check wear on this bushing. The bluing on the yoke is slightly worn off. No wear marks beyond that, gouges or anything like that. Bushing isn’t loose. Yoke seems to snap in securely. Retaining screw on cover plate is always tight. No yoke movement in frame.