I recently purchased a used - but in EXCELLENT shape - 1978 SW Model 60.
After putting approx. 25-30 rounds of WWB 130gr. .38spl through it, the 5th round would bind up and not allow cocking/more than half trigger pull. Upon ejecting the rounds, it dry fired without issue and also did so with snap caps after getting home. The gun was clean as a whistle and all ejector rods, assemblies, etc have been checked.
I noticed that when I bought the gun, the yoke screw was not the proper screw, as I could not tighten it without it causing a "rub" when I opened/closed the cylinder. I have since ordered a proper yoke screw assembly and it should be here next week.
Any suggestions as to what it could be? Here's a pic for extra measure