Please Help, my 870 is locking up when firing.

[SapperLeader]

Hello Everyone, still trying to get my new 870 up and running. The problem I posted about a few weeks back is still going on, but I think I was wrong on my first explaination. I did a deep cleaning, letting everything soak, and scrubbed the gun inside and out. I took it back to the range on friday, and once again got about 4 rounds through the gun before it started having trouble. After Firing, the 870 is locking up and requires a gentle tap on the floor to unlock, and then allows me to cycle the pump action. It was doing this if I pumped hard, or even if I pumped slow. Any suggestions? Help is appreciated, thanks.

 

[dfariswheel]

First:
Cock the gun, look at the slide release finger tab on the left front of the trigger group.
Pull the trigger and watch the tab. It should snap upward when the trigger is pulled. Check to see if it moves freely and fully up into the group when the trigger is pulled.

Field strip the gun, (barrel off, trigger guard off, bolt out).

Check:
The top rear edge of the bolt's locking lug for burrs.
The rear edge of the locking recess in the barrel extension for burrs.
The left slide bar on the extreme rear for burrs on the beveled (sloped) end.
The bolt lock bar front end for burrs. (This is the bolt release/bolt lock lever on the left side of the trigger group.
The bolt lock/release for free movement up and down.

Any burrs, galling, or damage to any of those areas can cause jamming.

Burrs or machining roughness on the lock lug or the lock recess in the barrel are bad about causing the bolt to stick. Burrs are common on the Express.

The gun locks the bolt shut by the lock/release moving up until the front end prevents the left slide bar from moving back to unlock the gun.
The front end of the lock/release has to slide down the sloped end of the left side slide bar.
Any roughness on either surface may prevent the lock/release from moving down far enough to allow the slide to move backward.

The bolt lock/release in the trigger group must move up and down freely, or the gun won't unlock.

 

[9mmMike]

When it locks up, try putting the gun down and let it cool. Five or ten minutes should be enough. Does it unlock? Could be a problem with the chamber of the barrel, too tight, rough or a burr. What ammo are you using? Can you try some different shells? Can you borrow a different barrel from someone long enough to run a box or two of shells through?
If it cycles OK until warm, it sounds like ammo or chamber related but, for sure, I'm no expert.
Mike

 

[christophera]

Wow. I'm having the opposite problem with my dad's 870. No matter how hard or how clean it is, it won't lock up.

 

[varoadking]

Magazine cap on tight enough?

 

[nhhillbilly]

Locking up 870

It sounds like when you fire the shotgun the fore end is moving back slightly and you then press it forward again and back. The gun unlocks very quickly and you must keep pulling the fore end all the way back quickly and forcefully to eject the shell and then pump it forward. I have had students do this in the past.

 

[gearbox]

I've had an identicle problem when using a 20" DRS IC Remington barrel on my 870E. The original 28" ribbed/beaded barrel was fine for the first few thousand shots until one afternoon I ran through 200rds in about 5min of skeet.
I'm still not sure if it's the locking lug, chamber, or heat. But I do know it's the the tab by the trigger gaurd. That definitely pops up as intended. Therefore I believe I can conclude that either the lug is remains locked for whatever reason, or the lug unlocks, but the shells base expanded in the chamber.

 

[christophera]

Magazine cap on tight enough?

Yes sir. It's on so tight that I can barely take it off. My dad thinks that the plating is interfering with it but my advice is to send it back to Remington. Bad juju either way.

 

[sm]

I have to agree with dfarriswheel's assessment and Dx.

Heat, I ain't saying it ain't so, never had it happen to me. When 3 guys share the same Express 870 and run 4 boxes through it on a 100* humid day with NO problems...not the first time we have run the guns to " break them in a bit quick". That's 300 rds in one day. We ran 2K rds in said gun in one week without anything more than a chamber brushing ,pipe clean extractor and a drop of oil here and there. At 4K a total clean and lube.

Now some of these fancy smancey oils and lubes won't cut it. Just because it smells nice and costs lots of $...use a good quality gun oil. Hell even the folks using Mobil 1 and ATF have better results than the touted stuff.

There is burr , something was forced being snug...
We run'em with RIG +P and Formula 3 break 'em in. Very LIGHT coating of RIG +P will let the gun run and not gall.

Designed to prevent galling in the guns that used to be subject to such before metallurgy became better. I do mean a very very light amount is all that is needed.

 

[SapperLeader]

Thanks everyone for the help! Im taking the gun apart today and Ill check it out for burrs. One good thing about all this, is that im really getting to know the 870 inside and out . Ill post again after I check out the guns insides this afternoon.

 

[DAT]

I bought an 870 express brand new in 1998 and had this problem. At the time there were several reoprts of this happening on thefiringline and shotgunsports websites.

Two factors seemed to be causing the jamming for me. The first was ammunition. I had jams mostly with Winchester ammo. Remington ammo didn't do it as much.

The second contributing factor was my form. When shooting shotguns I was taught to apply rearward pressure on the forearm to snug the gun into the shoulder. I think this was the main cause of the jams. I wasn't short stroking the gun, but the rearward pressure on the forearm was causing the action to freeze after firing. The jams stopped when I stopped putting the reareard pressure in the forearm

Hope this helps
DAT

 

[OrvilleYertleson]

I saw this happen at a recent IDPA match. The shotgun was brand new, and it fired certain brands just fine, but the cheap wal-mart value packs jammed it right up.

The shell was stuck in the barrel so tightly that nobody could get it out, and it had to be taken apart.

When I asked on eof my friends who works at a firearms shop what could have caused it, I was told that it was probably an out of spec barrel, and that he has to test fire every new 870 that comes into the shop now because he has had to return several in the last year that had out of spec barrels.

 

[49hudson]

DAT is exactly correct.

The 870's forearm should be laying in the support hand, with no rear or forward pressure.
The gun should be held into the shoulder by reward pressure from the
trigger hand's other three fingers.
On a really well broken in 870, the gun will unlock upon firing and is sometimes even partially cycled by recoil.

 

[SapperLeader]

Its been a interesting weekend, while I was off friday and saturday for the first time in two months, I spent most of that time nursing a sick little sister and running errands. Ill try to dismantle it tonight after work, and check out everyones suggestions. Thanks again for all the great responses!

 

[stglock]

Sapper,

Any feedback on this problem? I just experienced the same problem using Federal shells ($15/case) from Wall Mart

 

[SapperLeader]

stglock, the problem was fixed a while back. I took the 870 apart for a deep cleaning(2 times total), reassembled, grabbed 3 different brands of ammo(no winchester that time), and took her back to the range. This time, it worked fine, and after 2 or 3 hundred rounds, and a few range sessions alter, the gun worked fine with the winchester AA's that gave it trouble in the first place. If I was you Id deep clean the gun, and then try a variety of ammo through it.

 

[stglock]

Sapper,

thank you so much for the quick reply. I surely appreciate it . I will have to do serious cleaning per your recommendation.

Regards,

stglock