Magazine cap on 870 Express loosening?

[xm21]

Has anyone else had problems with the cap loosening?The Wingmaster barrel has a little detent ball that engages little depressions in the cap,the Express has little v shaped teeth inside the cap that engage v shaped teeth on the plastic magazine spring retainer.Not a problem hunting but at the range shooting skeet or sporting clays I have to check it often because it will loosen up.I have seen suggestions like wrapping teflon or electrical tape on the threads,and I have thought that maybe an extra heavy duty magazine spring might keep it from loosening due to more pressure on the teeth.I have looked for a steel magazine spring retainer but have not found one.I'd be interested in hearing how others deal with this.Thanks

 

[AndyJ]

Is your magazine spring retainer (and spring) captured in the mag tube when you take the cap off or does it go flying across the room?

 

[xm21]

AndyJ,the magazine spring retainer is captured on both types,the WingMaster and 1100's use the metal one that you use a screwdriver to pry out,it is only used to keep the spring flying out when cap is removed.The dimples in the cap and the detent ball on the barrel ring keep the cap tight.My Express has a plastic one that is removed by pushing down,past the little dents that have to be drilled out to put an extended magazine on,and rotated to allow to pop out.This plastic one serves to keep the spring from flying out when the cap is removed and to keep the cap from loosening on its own.It is much cheaper to make this setup than the one used on the WingMaster.But its disadvantages are having to drill or swage out the depressions in the mag tube if you wish to put an extension on(which I have no interest in)and in my case it does not seem to keep the magazine cap fom loosening up when it is shot a lot such as when shooting several rounds of skeet or a 100 round course of sporting clays.My 1100 never loosenened during use and my Ithaca 37,which also has a detent and dimple set up on its barrel retaining nut has never either.My Kuhnhausen shop manual shows the plastic mag spring retainer used on the 1100 special field model and 11/87 also,though it describes the 11/87's as being slightly longer.It calls the plastic spring retainer and matching cap late style.The metal spring retainer and the cap with the detent dimples are called early/intermediate style.

 

[AndyJ]

Good!

I was hoping you knew the purpose of the dimples because many don't and the cap will get loose in a Hurry!

FWIW, the teeth on the Express mag retainer are very aggressive AND plastic. Any chance the teeth or the serrations on th ecap have become worn?

I am not trying to be a know it all but a recent buying experience came to mind when I saw your question. I swear this is 100% true. I arranged the purchase of a used 870 Express FTF here in Dallas and the guy said he was a LEO ( and no slam of LEOs is intended here. My oldest son is Military Security Force.) Any way, I et the guy walking out if the appointed restaurant in Dallas and asked which car he was in so I could park near to him. He said " The cop car" Sure enough, there was a dark blue Crown Vic in the parking lot and I pulled in. The gun I was to purchase had a cut off barrel on it and part of the agreement was he was going to exhange it with an 18.5 RS barrel off another 870. As he was popping the trunk, he said I have to swa p the barrels. Neither one of the mag springs was captured correctly and there was stuff flying all over the trunk. I watched him reinstall both springs by just shoving them in there and replacing the cap.
Hence my question -- no disrespect intended.

 

[xm21]

Thanks for the reply Andy,no disrespect taken,and I have seen lots of posts where I where the fellow asking the question was not sure about what the part in question was called or what its function was.I went and took off the cap on the gun and there is some wear on the plastic teeth but not a lot,the gun is only a little over a year old.It has had about 500 shells shot through it.I bought the shop manual when I bought the new safety parts and extractor to replace the J hook safety and MIM ext.I am going to get the heavier police mag spring even though I have had no feeding problems,maybe the extra force exerted will help the cap stay tight.I read a post that talked about problems caused by overtightening with pliers,and I'm sure it would not be too good firing if the nut was too loose.The last time I shot it I went through three boxes of shells at skeet and when I went to clean it at home the cap was very loose.Do you know what damage might be done from firing it with a loose cap?The barrel ring and the cap was still close enough that the barrel did not move forward,but I was concerned that had I shot another round of skeet it might have gotten loose enough to increase the headspace or something.One last question can it cause damage to overtighten the nut?Thanks

 

[AndyJ]

I am gonna speak out of turn and just hope Dave M or Lee Lapin jump in with some solid info vs my speculation. I think upgrading the mag spring to correct your problem is money wasted. I would be getting a new retainer and mag cap from Brownells or Midway as the first step. I have never tightened a mag cap with pliers. I have *replaced* mag caps with the knurling gone to hell just because of that. I wish I could be more help but I am fast approaching the limits of my true knowledge here.

You are in the right place to solve your problem. Somebody will jump in here with the correct solution.

 

[xm21]

Thanks again for your help Andy.I did some research and most suggestions have been just to check it between stations at the range,some use neoprene O rings,and it is supposed to be an easy fix for a smith to drill a hole in the bbl ring and put the spring and detent in and stake it and order the new cap.