870 Express Magnum Fail to Feed

[Hankroberts]

A friend brought it to me to see if I can figure out what’s wrong. Before starting on it I thought I might get some ideas. Shooting 3 ½ mag shells most of the time, Winchester Supreme. The gun is virtually new, and very tight action. The problem has existed since the first time he fired it.

When the gun is cycled without firing, shell from mag drops immediately into the space below the bolt, on top of the ‘feed lever’ that pushes it up into line with the breech after the bolt moves to the rear. This is as it should be, far as I can tell. Cycling without firing works just fine. Snap an empty chamber and cycle a shell from the mag works just fine.

He says that when you fire a shell, the ‘feed lever’ flips up before the slide cycles, throwing the feeding shell under it to hang up. Not every time, but often enough to make it unreliable. I have tried cycling the action, but haven’t fired it yet.

I’m much less familiar with the 870 (beyond basic field strip) than with the Winchesters I use. Any suggestions where to start?

 

[Quickdraw22]

IIRC - the Express Magnum is only meant to handle 3" shells. The Super Magnum can handle 3-1/2" shells.

Maybe this could be part of the problem...............

 

[Hankroberts]

My Bad: it is a Super Magnum.

 

[Bearco]

Is he cycling it too slow?

 

[103M 95G]

send it to remington for repair if it is a new gun.

 

[Hankroberts]

Is he cycling it too slow?

No, I don't think so. He's no gun mechanic but he's adept with their use and he's owned 870s for a long time.

 

[Hankroberts]

send it to remington for repair if it is a new gun.

My statement that it is new is misleading. He's actually had the gun over two years; he just fires it very seldom.

 

[BSGA]

While I'm not very good at explaining things like this in written word, I'll take a stab at it. It sounds like the carrier is not being retained by the shell stop like it should. When the trigger is pulled and the hammer goes forward, the magazine release (shell stop) should let a shell exit the magazine and trip the carrier. The carrier is then timed to travel upward with a live round by the slide being pulled rearward and the slide pushes the rear of the magazine stop bar to the side, and engages the lift arm, allowing the carrier to lift. If I had to say without looking at it, I'd tend to believe the shell stop bar located on the left side of the reciever, is not being allowed to spring inward properly. There are 2 bars inside of the reciever, both staked in place. Keep in mind I'm working from memory, but IIRC the one one the left controls the carrier lift timing. It could be gummed up, bent, not engaging the slide bars, trigger group not installed properly, any number of things, but I'd say this is the most likely culprit. If that's not it, then it's the carrier latch or associated springs, plunger, etc. I hope this helps.

 

[Hankroberts]

While I'm not very good at explaining things like this in written word, I'll take a stab at it.

Actually, you ARE... and it does help: it confirms where I think the problem is, giving me a good start point. I had hoped to already be working on it, but the rain here has not allowed me to get outside and actually shoot the thing.

Plus, my son just called this morning to tell me they're in the process of increasing the number of Roberts in the clan (she went into labor about 800).

I'm afraid this is going to turn into a timing problem rather than an interference problem, but we'll see. Thanks for the input.

 

[BSGA]

Way cool about the youngun!! I need to add here, that after replying earlier, I took one of my trigger groups out to check it. It bugged me that I couldn't remember. Old age I guess! The 1100 has a carrier latch, the 870 does not. The 870 just has a dog on the rear of the carrier. The dog is on the right side, and as the bolt rides over it, it pushes the dog down, and cams the carrier upward. After looking at one again, I remember having one hang up on the inside of the reciever when one of the shell stop bars had come unstaked. It kept the dog in a lower position than it should have, allowing the carrier to lift. Also, in back of the dog, there is a hollow plunger that contains a spring. If that plunger is not free to move, or the spring is missing or weak, the carrier will be kinda floppy, for lack of another term. Sorry for the misinformation earlier, but I got some meds coming for the C.R.S. syndrome,,,

 

[Hankroberts]

>Way cool about the youngun!!

Yessir, it is. Still waiting, by the way.

>It bugged me that I couldn't remember.

Heh. Know what you mean. But as I'm sure you know, they say the memory is the second thing to go.

>The 1100 has a carrier latch, the 870 does not...

I'll check that. I went out between showers and fired it a few times, after reassembly (took it apart to just look). It was very tight and very dry, so I lubed it a little with silicone in the action. Couldn't make it malfunction, though I was using standard shells instead of the cannon rounds.

Gonna disassemble again, scrub the chamber (and the whole thing, while I'm at it), carefully lube the receiver moving parts with some Lubriplate (yes, sparingly), and try it again to see what happens. I'll look while I'm in there for any indication of improper placement/loose parts.

 

[Hankroberts]

Tore it down completely and scrubbed chamber, receiver and all parts. A heavy, thick substance peeled off the inside & parts of the receiver, almost like plastic laminate: I suspect a heavy packing lube that never got removed. It appears it was gumming up the internal mechanism, probably accounting for the very stiff action and hopefully for the timing problem.

Too late to shoot today, but will try tomorrow to see if the problem is solved.

 

[Hankroberts]

Final note on this issue. Took it out the next day and fired it with a mix of 3" & 3 1/2, standard & magnum loads. shot 9-10 times without a flaw.

Never, EVER want to do that again. I don't know anything I want to kill that bad. But the problem appears to be solved.