Remmy 870 Mag Cap Detent

SW CQB 45

SW CQB 45

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Having a slight problem with a dept shotgun.

the mag cap detent was stuck in and when the gun was shot, the mag cap was backing out.

ok, this area is abused or neglected in alot of 870s and is not lubricated.

I thought this would be easy, in that I would tap it inward to free up but I was wrong. I am now thinking this barrel has been this way since day one.

it will not go in. in fact I made a mess trying to tap it inward and the detent is all dented and probably over the size of the hole.

Remington said the barrel will need to be replaced. WHAT!?!?!?!?!?!?! I have the parts and tool to restake one in.

any of yall with know how or suggestions on what to do next, I would certainly take that advice.

If I remember correctled, this piece is potted metal and is sweated on on the barrel. so I will not use heat as it will likely melt the solder.

thanks in advance

870_barrel_3_.jpg
 
Having a slight problem with a dept shotgun.

the mag cap detent was stuck in and when the gun was shot, the mag cap was backing out.

ok, this area is abused or neglected in alot of 870s and is not lubricated.

I thought this would be easy, in that I would tap it inward to free up but I was wrong. I am now thinking this barrel has been this way since day one.

it will not go in. in fact I made a mess trying to tap it inward and the detent is all dented and probably over the size of the hole.

Remington said the barrel will need to be replaced. WHAT!?!?!?!?!?!?! I have the parts and tool to restake one in.

any of yall with know how or suggestions on what to do next, I would certainly take that advice.

If I remember correctled, this piece is potted metal and is sweated on on the barrel. so I will not use heat as it will likely melt the solder.

thanks in advance

870_barrel_3_.jpg
 
The barrel support ring is not "potted metal" it's pretty tough steel.
It's brazed on the barrel with a high-temp brazing compound.

What I'd do:

Put a good drop of Kroil in the hole and let soak overnight.

Get a small diameter center-type punch and grind the end to a rather needle-like point.
CAREFULLY use the long, sharp point to UN-stake the staking around the detent until it can move up enough to be removed.

Another technique that sometimes works is to use a rounded end, tapered punch that will fit into the hole and use it to expand the staked hole until the detent comes out.

Tapping the ring with a plastic hammer helps break the detent loose.

Either way, don't expand or open the hole mouth more than necessary, lube up a new detent and spring and re-stake in place.
 
it was stuck flush when I discovered it.

I got it to that point with a center punch.

I will try a thinner pointier punch touch.

I believe the detent has expanded in the hole.

about 6 years ago, the Rem Armorer instructor told us to be careful with the mag tube lug on the barrel as its potted metal that is soldered on.

This past year's recert, they made no mention of this part and the instructor told me to get the barrel replaced.

Not for a $6 part.

we will see what happens. thanks
 
I believe the magazine tube ring is a sintered metal part (fused from molded powdered metal) and is silver soldered (brazed) to the barrel.

Removing that ring is a real bugger because you need enough heat to melt the brazing. Certainly enough to discolor the barrel finish, and possibly enough to distort the bore.
 
The one's I've experienced are as J/T described. It's do-able but not at the typical handy mans level of tooling and talent. By the time your done doing what you have to do to salvage the barrel, you'll have paid for a new one + shipping. JOMO?
 
if I cannot removed the current stuck detent,

I plan to order a new mag spring retainer and mag cap. I will figure out a way to put dimples in the mag tube to hold the plastic retainer.
 
If the barrel isn't too long, i.e. 18" or less, see if you can find a drill bit the right diameter that is long enough, drill a new hole for the detent across from the original and install it there.

KAC
 
If you could somehow drill it (maybe with a dremel tool) you could thread a screw into it so you would have something to grab. Or,(I know nothing about it's design) you could drill a precise hole from the backside to knock it free, then thread it 1/4NC and install a 1/4 allen set screw at the depth the detent spring needs. Then coldblue the hole.
 
Over drill (if you can find a chuck or quill that will clear the barrel?) from the back side, JUST to where the raceway for the spring/dog is for the detent, drive it out. Leaving intact the now stepped interior profile (it now resembles the chamber for a bottlenecked cartridge) Fabricate a new retainer pin/dog that will protrude the correct amount, but be limited in it's travel by the newly created "bottleneck". Find/fabricate a spring that will be of correct length. Tap the rear side opening just deep enough to allow for a nylok vibration proof hex plug. Or use a Welsh plug or a de-anviled primers body as a plug.
Told you it was a PITA!
 
One possible fix that would involve more supplier searching than bench work is an aftermarket slotted sling mount. There are some out there that slip over the mag tube between that ring and the mag cap -- with an integral detent. I've got one on an 11-87, but it doesn't have a brand mark on it (I think it might be Wilson/Scattergun Tech, but don't really remember).
 
Which color loctite is non-permanent/easier to remove? Blue? Problem solved, loctite the mag tube cap on. The Express models don't even use the ball detent, just a really snugged on fit on mag cap.
 
the express guns do have retention on the cap.

its a toothed plastic insert which is mag spring loaded and locked in place with two dimples on the mag tube.

the inside of the mag cap has opposing teeth to mate up with the plastic insert.

extended firing will cause the mag cap to turn if there is no retention device.

loctite is not an option.

if you scroll down, you will see the plastic insert http://www.ar15.com/forums/top...tml?b=6&f=1&t=177067
 
You never stop learning, and one of the neatest ideas I've heard lately for securing 870 mag caps that have no detent, is to simply put a rubber "O" ring on the magazine tube after the barrel is on.

Someone who'd removed the "dimples" from his Express for an extension and wanted to go hunting realized that his cap wouldn't stay put without the detent system.
So, he just put an "O" ring on it and was off to shoot ducks.
 
This is a police dept gun.

while this may work for hunting guns, I would prefer to fix it correctly.

thanks for all the advice.

All I need is for an officer to field strip, lose the O-ring and the cap is put back loosely and then comes off when its needed.

I have to document my fixes for liability purposes, but thanks for all the suggestions.

I want to try and remove the culprit and fix. my only other option is to make this gun a full time four shotter with the plastic insert and different mag cap.

take care
 
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