Binding Cylinder

[Kingshouse41225]

When I was a young boy my grandfather had a M37 that he had purchased used. I remember even back then the trigger would gradually build in stiffness as it went around, then suddenly loosen up again. He had it "worked on". I now have then gun and have replaced the butchered extractor, cylinder stop, and hand, but the problem persists, perhaps now worse than ever. Without the trigger or cylinder stop installed the center pin locks up nicely and the cylinder turns true. Nothing appears to be bent. Any suggestions?

 

[Alk8944]

First place to check is swing the cylinder out. Spin the cylinder while watching the end of the extractor rod. If it has a significant wobble this is probably the cause, a bent extractor. It doesn't take too much to cause binding on 1-2 charge holes if the locking bolt (in the barrel lug) is fit tight.

 

[Kingshouse41225]

The extractor is new and the problem existed with both the old and new extractors. The ejector rod has a definate rub mark, it is opposite the tightest cylinder. When you spin the cylinder by hand it does not look bent but I put an indicator on it and it has .010" runout. When the tightest cylinder comes into registry the ejector rod moves a LOT, never noticed that before. I would assume the next step would be to replace the ejector rod and see if that helps.

Should I also be looking for a bent base pin, or would that that not matter if the extractor/ejector rod is OK?

 

[Alk8944]

Chances are the base pin is fine. And, yes, .010 is plenty to cause the binding.

Amazingly, and I know I will get an arguement from some on this, sometimes it is possible to loosen and re-tighten the extractor rod and it will be straight. Excessive tightening can easily crush the small shoulder of the rod or even crush the extractor rod collar. If you replace the rod buy a new collar too, no one ever seems to think it may be the problem.

 

[Kingshouse41225]

I took some measurements.

The ejector rod is definately bad. The forward end of the rod only has ab0ut .010" of runout but if I support both ends of the assembled ejector I get more like .017" runout in the center. The center pin is bent about the same amount.

I have already replaced the extractor and have the pin and ejector rod on order. I'll post the results when the parts arrive.

Thanks for the suggestions so far.