View Full Version : An 870 magazine cap safety question

August 7, 2008, 09:31 PM
While digging through my box-o-gun-junk I happened to come across what I feel pretty sure is a magazine cap for a Remington 870 with the sling swivel stud already attached. Since I just acquired a 20 ga 870 and since it needed a sling I decided to see if the mag cap I found would fit. It did.:)

The cap with the swivel stud is not the kind that locks up via ball detent but apparently uses a different system. Since my other 870 used the of ball detent retention system I'm not sure how this cap was supposed to be secured but that's not my question.

Questions: The swivel stud equipped cap screws down very securely even without the ball detent & secures the barrel as well as the swivel-less cap that came on the firearm from the factory. Am I at risk substituting this found-cap for one with dimples in the cap rim that's actually designed to use a ball detent for retention? Anyone ever tried this?

Much obliged in advance for your POV.



August 7, 2008, 09:46 PM
I recently did a similar "swap" on my Benelli. In my case, I added a sling swivel bracket that didn't allow the spring detent to align properly. I was a little concerned about it as mine didn't lock up as yours apparently does.

A trip to the local ACE hardware store seems to have fixed my problem....for 37 cents. It made a trip to the range last week and with a variety of bird, buck, and slugs going down the barrel, it worked great. Didn't loosen up a bit. :)

Here are a couple of photos.


and with it installed......


August 7, 2008, 10:59 PM
Selfdfenz does your shotgun have mag tube dimples? The other cap retainer system Remington uses is a ratchet plastic spring retainer that engages the cap to keep it from loosening.

arizona98tj Looks like a good idea. I might try it on one of my shotguns with a tube ext. I would like the Oring to be a little thinner so it want add much length.


August 7, 2008, 11:06 PM
The original Remington design uses a spring and ball detent on the front of the barrel support ring that interlock with the "dimples" on the outer diameter of the magazine cap.

The newer "Express" models use a plastic tube that fits into the magazine tube to retain the cap.
This plastic tube has some jagged "teeth" that interlock with some machine-raised "burrs" inside the new style cap.

The only "watch out" in interchanging cap designs is to keep an eye on the cap to be sure it doesn't vibrate loose under recoil.

The "O" ring is the best answer I've seen to secure an 870 cap to interchange caps.

August 8, 2008, 11:47 AM
Thanks one and all,

Great info.

My 870 has a steel mag tube and the detent ball I spoke of is actually located on the barrel ring, which is what I'm familair with. The mag tube itself has nothing that will engage the little "teeth" I now see up inside the substitute cap. (I hadn't noticed them before, thanks)

I like the O-ring idea but I'm not sure there is room for one. As it currently stands when I tighten the swivel stub equipped, substitute cap on this thing it screws down so tight it's hard to get off if I use a lot/too much elbow grease when I scew it down. The factory cap is easy to remove by comparison.

Before I trust it completely I'll follow your suggestions and give it a thorough "road test" at the range with several types of ammo.

Not being much of risk-taker I genuinely appreciate your input. I hope you all have a wonderful weekend.



Scattergun Bob
August 8, 2008, 01:43 PM
You just have the politically correct mag cap. You could go to the gunshow and get the right one with a sling stud. If you wish to keep the current one, try 2 turns of teflon tape as a thread lock, has work for me in the past.

Good Luck & Be Safe

August 9, 2008, 08:33 AM
My Rem 12ga cap with stud is set up to work with both systems---it has teeth on the inside and notches on the flange for the ball detent.

Maybe yours is the same way??

James K
August 9, 2008, 11:48 AM
If you want to keep the old cap, just drill and tap it and install a swivel.


August 9, 2008, 11:54 AM
If you wish to keep the current one, try 2 turns of teflon tape as a thread lock, has work for me in the past.

Yep, that's worked for me before too.

You can also put one of the plastic magazine retainers on top of your spring, the kind that are usually held in place by the dreaded dimples. Used in place of the old style wingmaster spring retainer this works to hold the cap in place even if the dimples are gone. Simply be careful when removing the cap that things don't go flying. All the dimples do is keep things in the mag tube, they have nothing to do with keeping retainer pressure against the mag cap. Mag spring does that.