870 Express 3" Mag Feeding Issue


February 13, 2013, 10:14 PM
There seems to be an issue cycling 3" mag shells through my 870 Express. It's an older model, probably from the late 80's or 90's, but it is the magnum version. The problem appears to be when I cycle 3" mag shells when unloading. Basically, they seem to "stick" when going into the chamber, which jams the action. Vigorous working of the slide sometimes clears it, but not other times. The gun is clean, and was lightly oiled.

2 3/4" shells cycle flawlessly. Always liked these guns, I feel like they point like my finger.

Am I doing something wrong? Anyone have similar experiences?

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February 14, 2013, 06:09 AM
Are you are turning it sideways to watch and working the action slowly? Does it look like the carrier is lifting the shell high enough? Have you taken down the trigger group any and cleaned all the springs and spring pockets?

February 14, 2013, 12:59 PM
The problems when held upright, or at an angle to watch. The clean part is in reference to the bolt, rails, and inside of the receiver. I have never taken apart the trigger group.

I *think* the carrier is not coming up all the way, but can look closer. The only 3" shells I have are buck shot. Cycling the gun a lot makes me and the wife a little nervous, but I will confirm the carrier with both 3" and 2 3/4" shells.

February 14, 2013, 05:14 PM
Does it have the original (2 3/4" & 3" shells rollmark) barrel?

If it's a HD shotgun many people feel 3" is overkill and just lead to slower follow up shots (heck even "reduced recoil" 2 3/4" shells do the job just fine). That doesn't solve the problem of course but just something to think about.

AI&P Tactical
February 14, 2013, 05:57 PM
I am unclear on your issue. Are you shooting the 3" shells ? Or, are you just cycling them in the weapon and if so, why?

Did you purchase this weapon new and if not have you check the barrel to see what it is chambered for?

How old are the 3" shells and if older ammo have they be left loaded in a weapon? Shells left loaded for extended periods can bow out from magazine spring tension.

If it is infact a 3" chambered barrel, when was the last time you clean/polished out the chamber?

February 14, 2013, 06:47 PM
Cycling appears to be necessary to unload it. I bought this gun used, and it is marked as for both 3" and 2 3/4" shells. Haven't polished the chamber, but it looked fine. Otherwise I used a 12 gauge Bore Snake for cleaning. I will confirm the place where the shell fails to load (i.e. either the lifter doesn't bring it all the way up, or it's sticking on the way into the chamber.

I've never had the trigger group apart before; did I miss some important maintenance?

February 14, 2013, 07:24 PM
One common cause of failure to chamber in the 870 is a gummed up or weak "carrier dog spring".
This is the spring that powers the shell lifter.

If the spring is fouled or weak, the shell lifter may not rise up fully and the shell may catch below the barrel.

Clean/replace the spring. if you replace it, buy the stronger Police version spring.

Here's a schematic. The spring is part number 62:


February 16, 2013, 07:07 PM
Cycling appears to be necessary to unload it.

Nope. Just after the slide begins to move rearward and before the shell is released from the magazine, you can use your finger to push the shell lifter all the way up against the bottom of the bolt. Continue to slowly move the slide to the rear and catch the shell with that same finger when it releases from the mag tube. Rinse and repeat.

PLEASE try it with snap caps first....

February 16, 2013, 07:41 PM
This probably not the cause but I have some 3" S&B buckshot and, due to the crimp design (they use a "cap" roll-crimped into place), are actually a little longer than regular 3" unfired shells....same with their 2 3/4" buckshot....about 1/8" or so longer. Might be worth looking into.

FWIW, I use my fingers on the tabs and unload through the bottom.

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