Rem. 870 Express - Super Mag

[lazyMlazyK]

I've got a 12 gauge 870 Express (I know, it's a cheap, CHEAP firearm - bought it in college from an acquaintance) that seems to be kind of picky on ammo. The action "locks up" after firing, mostly with cheap Winchester Super X, but also happens at times with Fiochi. Low and high brass. I've polished the chamber with Iosso and steel wool, and removed any visible burrs from manufacturing. I've also replaced the extractor, but that hasn't made a huge difference. When it locks up, I sometime have to mortar the buttstock on the ground to get the spent shell extracted. I have had no problems yet this year with Federal Upland low-brass, but would like to be able to run cheaper ammo (I miss alot of doves, but have fun trying).

Being a Super Mag, I like that it's got the capability of firing 3-1/2" shells for geese at times, but I'm about at my witts end with the damn thing locking up on me. I subscribe to the idea that a cheap pump should be able to reliably cycle any ammo, cheap or expensive - maybe I'm wrong in that belief? I'm about to look up shotgun chamber specs and start taking measurements. Maybe mine's a bit tight?

Yes, I've already taken it to a gunsmith, they polished the chamber and that was it.

 

[Petras]

My first shotgun was an 870 express super mag. First time I ever took it out hunting I experienced the same issue as you, but only when shooting 3.5". Ended up taking it back in to Big Bear in Minot where it was purchased and they ended up ordering me a new barrel as the one on it was stamped for 3.5" shells, but was not machined for 3.5" shells. It has worked flawlessly ever since. This was roughly 26 years ago so likely not the same issue as you are having, but it's a place to look anyways...

 

[SDMF]

Pull the extractor again and clean out the extractor spring and the hole the spring sits in. I'd also pull the bolt out and make sure you don't have any grit in/around the recoil lug that sticks out the top when the bolt is in battery.

 

[lazyMlazyK]

Pull the extractor again and clean out the extractor spring and the hole the spring sits in. I'd also pull the bolt out and make sure you don't have any grit in/around the recoil lug that sticks out the top when the bolt is in battery.

It usually doesn't have a problem extracting the shells, mostly just has problems cycling the action rearward after firing. I'll check it out though.

 

[rodcontrol]

It usually doesn't have a problem extracting the shells, mostly just has problems cycling the action rearward after firing. I'll check it out though.

I have the exact same issue with my 870.....I think the chamber over time wears down and the shells actually expand inside the chamber causing them to get stuck.

 

[lazyMlazyK]

Think I found the main issue. Don't know why I didn't think of it before, but I put a borescope in the chamber over lunch to get a better look, and spotted this nastiness on a portion of the chamber, at the base of where the shell rim would sit. Strange that I don't see impressions from this on the spent cases, but I'm thinking this would be enough to cause failure to eject issues. Now my question is - could a guy fill the pits with something like JB Weld and sand it down smooth? I know that's pretty redneck, but this is, after all, essentially a truck gun. Looks pretty bad in the picture, but its hard to pick up with the naked eye.

 

[870XPRS]

I have the exact same issue with my 870.....I think the chamber over time wears down and the shells actually expand inside the chamber causing them to get stuck.

Had the same issue after thousands upon thousands of rounds and multiple stocks....I agree with your diagnosis.

 

[FightingSioux]

Never had a problem with a shotgun once I switched to a semi auto. 870, nova, were nothing but issues for me

 

[svnmag]

That may be the issue. I would still (per previous post) check if a spent 3 1/2in will fully chamber without pinching the mouth. I like your redneck fix. I hope you try it with viable result. If my memory is correct a 3in .410 and 3 1/2in 12ga share max SAAMI chamber pressure: Anyways; I'd be very curious to see if a hardware store patch could restore/emulate original performance and avoid purchase from Hastings.

Also IMO: NO Remington 870 is a cheap POS. "Retarded" is another story. They helped kill the 16ga by using 12ga frames.

That is all.

 

[svnmag]

Any updates?

 

[SDMF]

It usually doesn't have a problem extracting the shells, mostly just has problems cycling the action rearward after firing. I'll check it out though.

If the extractor spring gets gritty/dirty it'll jam up the works. Grit in the spring sort of "pins" the hull up against the far chamber wall and wedges things shut. I've "fixed" several 870's with a can of brake or carb cleaner, the little red straw to concentrate the spray, manipulating the extractor as you spray, and a shot of spray-lube after the solvent dries (wear glasses). Less often, but, another possibility is buildup in the lug recess in the top of the bbl or behind the lug in the bolt.

 

[lazyMlazyK]

Any updates?

Not yet. I filled most of the pits with JB weld and sanded them flush, but noticed that I missed a couple spots, so had to do it again. Hoping to have some updates within the next week or two.

 

[svnmag]

Not yet. I filled most of the pits with JB weld and sanded them flush, but noticed that I missed a couple spots, so had to do it again. Hoping to have some updates within the next week or two.

 

[lazyMlazyK]

Well, the Bubba fix seems to have worked! Took the 870 out over lunch break to test out some known problems ammo and there was no more having to mortar the buttstock on the ground! The extractor did slip off the couple of Kent shells that I tried, but that might just be a weak or dirty spring. I'll clean that up tonight and maybe even get a replacement spring coming. The Kent shells popped out easily enough on the second attempt at ejecting them.

Looks like she'll shoot the cheap Winchester Super X dove loads now!

 

[SDMF]

Did the JB stay in place or did it eject w/the shells? I didn’t expect that to stay in place when you added significant heat and 10-15K PSI.

 

[lazyMlazyK]

Did the JB stay in place or did it eject w/the shells? I didn’t expect that to stay in place when you added significant heat and 10-15K PSI.

It stayed in place, no chipping any damage to it that I can see. Fired off only about 12 rounds, but it's looking promising. Taking my boys on a dove hunt in the morning, I'll report back with field results sometime this weekend.

 

[svnmag]

I emailed an engineer about your attempt he's a bit skeptical even if you use the 1000F version. I hope you keep updating--Thanks

Also, to my plebeian way of thinking; the expansion of the case should assist holding the patch if place(?).

 

[svnmag]

Emailed the engineer again with additional concerns even as I hope this works:

Well, the guy patched the large pits in the chamber, sanded flush and the gun is working as it should. In my plebian mind; I'm hopeful the expansion of the case may help secure the patches...I also think he bought a defective bbl. The "pits" were more like potholes and he may be just extending the time of failure. I wouldn't shoot this gun without safety glasses. Well, I don't shoot without glasses period...

Also, what will be the effect of erosion vs steel vs JB Weld?..

Here is the unpatched chamber:

 

[lazyMlazyK]

I emailed an engineer about your attempt he's a bit skeptical even if you use the 1000F version. I hope you keep updating--Thanks

Also, to my plebeian way of thinking; the expansion of the case should assist holding the patch if place(?).

I am an engineer, just not the mechanical kind. The JB weld has a pressure rating of 5kpsi, but with it being on the wall of the chamber where the brass sits, I would think that would help to hold it in place. I'm sure it'll wear down/off over time, a d that this is only a temporary fix, but I'm hoping it gets me through another season or two. I've gotten into PRS, so that's where all my fun money goes these days. Would love to get an inertia-driven semiauto one days, but they sure don't give 'em away!

 

[svnmag]

In full disclosure--I'm really pulling for you as I have an exhaust leak it my truck (manifold) and am contemplating the same thing. I of course ASSumed you were a regular scrub like myself...I read constantly about firearms and am blessed with a couple real smart friends.

Anyways, looking forward to the updates. Good luck on the dove shoot!!