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 Post subject: mystery noise
PostPosted: Fri Mar 06, 2015 11:42 pm 

Joined: Wed Feb 25, 2015 2:30 pm
Posts: 44
Location: London ont
After doing a deburring and lube ,my 21 panther makes a grinding sound when you cock it. It is when it is 3/4 cocked each time. It has a chopped mainspring (from the factory) with the cut end going in the piston first. The rifle was dry from the factory so i didnt shoot it until I lubed it.Would a chopped spring make a grinding noise? Any other ideas? thanks for replies

 Post subject: Re: mystery noise
PostPosted: Sat Mar 07, 2015 12:36 am 

Joined: Mon Mar 04, 2013 3:59 pm
Posts: 306
Location: Hamilton On
Does the 21 Panther have the thin metal sleave around the spring? My Ruger Blackhawk, which I believe is a clone of the 34, has the sleave and it was contacting the spring at about the same point in the cocking cycle. I removed the sleave and peined the edge that was catching the spring ever so slightly and that fixed the issue.

 Post subject: Re: mystery noise
PostPosted: Sat Mar 07, 2015 3:35 am 

Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1271
Location: United States
That's about when the pressure of the piston skirt against the tube is greatest and most common area to get damaged. It's all about the angle of the cocking linkage and spring pressure. They seem to start digging in with the barrel at ~90 degrees, then the spring pressure increases with little angle change, then near the end of the stroke the spring pressure is highest but the angle is less so the scraping is reduced. Make sense? Probably not, but if you look at a parts diagram and/or your gun with the stock off you can visualize what's happening. The cocking linkage pushes the piston back, but you can see it isn't straight back. With the barrel ~90 the linkage is pushing back and up so it's forcing the rear end (skirt) of the piston up against the receiver tube just under the scope rail. If the area is greased and the skirt has no sharp edge to dig in then it should be ok, at least as long as you keep it greased. The edge of the skirt will wipe grease away which leaves a minimal coat. The skirt is typically hardened and the receiver not, so unfortunately the receiver loses.
If you used silicone grease, silicone spring tar or oil, then you're screwed and need to take the gun apart and do some repair work.
There's also the cocking linkage itself, the "shoe" which is the end of the linkage and touches/pushes the piston. If it's resting down low against the tube, which is should, via gravity, then when you start cocking it the tip will be pressed against the piston which should lock it in place against the piston, meaning no sliding up/down. Then as the linkage angles downwards during the stroke the shoe will tilt too which means the rear edge of the shoe which was parallel with the receiver tube is now lowered down into the metal. Normally the shoe is shaped with an angle so this won't happen, but things don't always work out. If it worked before then it should be fine now, unless you messed with it my doing some sanding on the shoe.
Another is the linkage just forward of the shoe scraping the side of the slot, but again if it worked before....
Yet another is if the linkage bows to the side under pressure while cocking, which I doubt is your problem but some guns do and the linkage scrapes the stock which is obviously metal to wood or plastic and I assume your problem is metal to metal? So being metal I'm guessing that piston skirt is the problem.
Then there's what Tinner mentioned, but usually that makes a distinct sound because the coils of the spring pass over the spot one at a time to it's clunk clunk clunk or scrape scrape scrape. If the spring is canted it can scrape that inner liner in the piston with a more even sound, but it shouldn't be bad at all, and almost nothing if greased.
So more details on what you did, the sound it makes, and how it feels. And when it scrapes can you feel increased friction in the form of more cocking effort, or is it noise only?
If it's the skirt scraping then it can be repaired, and the piston buttoned to prevent this problem happening again. Buttoning is a must do mod anyway imo, which will not only solve that friction problem now or in the future, but also reduce cocking effort and make cocking smoother. The inside of the piston can be sleeved in plastic as well which does a similar job between the piston and spring, and greatly quiets the twang when fired.

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