Tuning up an 870

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MrGiggles

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I bought an 870 Express Mag a couple years ago from a pawn shop. There's no telling how many rounds have been through the old gun, but it's still in pretty decent shape. I've got a renewed interest in busting clays and would like to get this gun running smooth again.

The first issue is that the spent shells don't really eject and just tumble out. I've noticed that it will fling a live shell with authority though. What gives? Everything looks to be in good shape. Very seldom does one not make it out at all, making it not much of a problem.

Occasionally, after extraction, the next shell will jam halfway in the chamber. If you fiddle with the pump some it will go. Any idea what might be causing this?
 
Sadly, the man who has the most experience with this was driven off THR last night by malicious accusations, so I'll try to answer in his stead. The extractor spring needs to be replaced. Easy to do, there are You Tube vids on it. As for the other issue, 9 times out of ten, FTF (failure to feed) on an 870 is caused by operator error, namely, not working the action vigorously enough. The other 1 of 10 is a worn carrier spring. Not as easy as the extractor spring, but again, there are You Tube vids on trigger assembly work.
 
By extractor spring, do you mean the flat spring that's riveted to the receiver, or the spring that works the extractor claw in the bolt?
 
The extractor is in the bolt. The ejector is riveted into the side of the receiver. You need to replace the extractor spring. That's the easy one. As long as you're doing it, I'd replace the plunger and the extractor itself also.
 
870 tuning for me, anyway, consists of polishing the chamber, having a good sharp extractor hook and strong spring, adding the flex tab lifter, and, if the action bars bind, stoning them to smooth them up. The Timney trigger kit is a good idea but I haven't done one yet.
To smooth up the action I have resorted to polishing all the finish off the action bars on the for end (got to take wood off first) then blueing them up, reassembling and pumping fifty or so times (don't need bolt in for this). Disassemble and stone and polish the high spots (shiny places) to lower friction.
Degrease the action, bolt, and bolt support, polish off any burrs an lube. I like white lithium grease.
I have one that has gone a couple hundred K rounds and if you hold it vertical and tip the release the slide will drop to wide open.
Don't do anything to the locking notch in the barrel or the lockup bolt unless a burr has been peened into it.
To my dismay, I have found that complete for end assemblies don't always interchange (same gauge).
 
I used to put GunSlik on the action bars and work the action until it was smooth, then take it off and lube with BreakFree. Back before flex tabs, we'd mill a slot in the carrier to shove a key or knife blade in if necessary.:uhoh: I never had to use it in any of my 870's thankfully.
The only trigger work I ever did was put a lighter spring in, and big head safety.
 
As long as the extractor is hooking the rim of the shell and pulling it out, I don't think it needs replacing. Sounds to me like possibly the chamber needs a good cleaning since only fired shells are dragging. If you operate the action smartly, you do not even need the ejector spring, as the step on the ejector will kick the shell out. The spring was added for those who want to turn the gun sideways and watch. It is easy to join the parts changer's guild and waste a lot of money on an 870.
 
"It is easy to join the parts changer's guild and waste a lot of money on an 870."
^that right there is funny good!
Te earlier Express models were usually pretty smooth internally. Start with a real good cleaning and polish the chamber. I would be surprised if that doesn't fix it.
 
The ejector is visibly okay. I'd rather not replace it since I don't have the rivet cutter. Would bending it out a little help?

I may just be short stroking it, I'll try to work it differently this weekend and see if that helps at all.

It is a newer model with the flex tab carrier.
 
Several hundred thousand rounds with three 870/1100 guns I've yet to need an ejector replaced or fiddled with. Firm stroke. Don't ease the slide back.
 
I'm betting a good cleaning is all it needs. Even when new some of these had rough chambers that needed polishing. I am of the opinion that the Express is every bit as reliable as the more expensive Wingmaster. But sometimes small things such as getting the chamber polished needs to be done after purchase. That is the difference between a $290 shotgun and a $700 shotgun.
 
I ran a couple boxes of shells through it today.

The extractor and ejector seem to be working okay.

Maybe one out of five doesn't seem kick up all the way into the chamber and catches. Would this be a worn carrier spring? If that's what works the carrier, it makes sense to me.
 
Mr. giggles, have you taken a very close look at the front of the chamber to see if there is maybe just a bit of fouling build up, possibly wad deposits that are hard to remove? Just for my own curiousity, is this only occurring with one brand of ammo? I only say this because years back, I had a particular pump gun that disliked Federal shells with the ribbed hull. Any smooth shell was flawless. Never did figure out a reason why!
 
grouselips1 said:
Mr. giggles, have you taken a very close look at the front of the chamber to see if there is maybe just a bit of fouling build up, possibly wad deposits that are hard to remove? Just for my own curiousity, is this only occurring with one brand of ammo? I only say this because years back, I had a particular pump gun that disliked Federal shells with the ribbed hull. Any smooth shell was flawless. Never did figure out a reason why!
Click to expand...

I've never had a shell stick and lock up the slide, so I don't think there's anything wrong with the chamber. They just don't seem to make it all the way up there reliably.

Ive had it act up with many brand of shells.
 
Dropped the new follower spring in last night. Pretty significant difference between new and old.

Haven't ran enough shells through to see if it fixed the problem though.

 
Start with a really good bath.
Manual is here. Won't be much help though.
http://stevespages.com/pdf/remington_870.pdf
The exploded drawing will and that's here. The Ejector is part #18. Its spring #19.
http://stevespages.com/ipb-remington-870.html
Part #'s 17 and 20 on Gunparts site. You need the Super Mag ejector spring. $8.85 for the spring.
"... the more expensive Wingmaster..." Wingmasters weren't always the higher end model either. Mine's a Wingmaster and certainly doesn't have the high end stock on it.
 
I have owned three 870 Wingmasters (one from the late '50's and two from the '60's). All were used and very slick insofar as operation, and IMO much better than any Rem 870 Express these days.

If you are having a problem with the new round not chambering and getting caught up in the action before chambering, you are short shucking the slide. I have heard about problems chambering and extracting rounds in the newer Express models but have no experience with that. I will defer to the others here that recommend polishing the chamber, et al.

The older Wingmasters had a plain solid shell lifter and there was a small cure for getting around the short shucking problem if it happens.

I don't know what your shell lifter looks like but a fix for that (if you get in a short-shuck jam) is a slotted lifter (which I installed on all three of my Wingmasters) so you can use a screwdriver or similar tool to move the stuck round into the chamber. This part used to be sold by LL Baston 2 decades ago, I doubt they are still in business, and I am not going to look it up for you.

Good luck!

Jim
 
Shot the crap out of Wingmasters and Express, owned maybe six of each.
No problems.
Newer stuff might be less polished.
New style shotgun shells (steel rim) seem to be problematic for many.
I don't shoot that junk............and have no problems.

Also don't even think about pumping my gun.

I just do it, pop multiples on doves every yr. Current 870 is an older Supermag. It's not smooth as older reg Exp I had......but it runs fine.
 
Just anecdotal here, but I've heard that in addition to polishing the chamber on an 870 Express, it helps to polish the interior surface of the barrel flange to reduce friction with the edge of case rims as they are being extracted/ejected.
 
I have owned I think seven Wingmasters and Expresses and worked on more than I can recount. I never called myself a real gunsmith because wood hates me and I have zero artistic ability, but I was more than a fair gun mechanic.
If the shell is in front of the bolt, you are not short shucking it.
If the shells are going out the ejection port, the extractor, extractor spring, and plunger are fine.
If a gun is run dirty and/or with no lubrication it is rare but not unheard of for the notch on the action bar and/or the carrier dog to become worn and to start slipping out of engagement before raising the carrier all the way up, especially with the weight of the old lead Magnum shells on it. The cure is the heavier carrier dog spring, which is also part of the Police package, to try to eliminate any possibility of this problem in a life and death situation.
 
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