870 M.M. issue or am I getting senile in my old age ?


September 17, 2008, 01:18 PM
O.K. Picked up a new 870 M.M. and it is my first remington 12GA.

Now I load the tube up w/ 6 rds and try to load one into the chamber but the slide will not move unless I depress the silver lever on the left side,just front of trigger assembly.

My last 12GA was a mossy cruiser and do not remember having to do anything to chamber a rd ?

It does have this odd lock system on the safety button,it is unlocked...and what the hell is this thing anyways,my buddy turned it and it locked everything up and of course mine did not come w/ the green key to unlock it.....:banghead:

So after a trip to joe's sporting goods to unlock it and I asked the guy at the firearms counter and he says I have to depress that silver lever to chamber a round .....o.k. well when I do this the shell drops into the carrier but it will not lift up to chamber it.......:confused:

This is a new piece,never fired,bought from a LEO friend who got it new assembled it for a demo for his squad and I got it.

I am waiting for the seller to get back to me but figured I would ask all you wise ones here ....

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September 17, 2008, 03:06 PM
What the heck is a "M.M."????

When loading rounds into the magazine, be sure to push them as far as you can into the magazine, not just til you hear the first click.

When the bolt is locked forward, you MUST push the action release lever if you want to open the action. That's the way the gun is designed.

If you have the magazine loaded and wish to load one into the chamber, push in on the action release lever and pump the handle HARD to the rear and then HARD forward. That should load a round into the chamber.

As to the locking safety device, they are a PITA. I've got one of those keys somewhere, but I never do anything to lock the safety. In fact, my Wingmaster doesn't have the locking safety.

September 17, 2008, 03:47 PM
Not the safest thing to do---but you could always just pull the trigger.

September 17, 2008, 03:56 PM

Not the safest--when dealing with live ammo, correct? I have some dummy "snap-caps" that I got with my 870 to help familiarize myself with the function cycle. In the situation that I have the magazine full but empty chamber, can I dry fire and rack it, chambering a round without damaging anything?

September 17, 2008, 04:13 PM
Marine Magnum

September 17, 2008, 04:42 PM
Sorry pete a marine magnum ...:D

Well that's a new one to me to have to press the lever to chamber a rd,not sure what the purpose of that is but considering this J lock I am not surprised .

Well I tried it again and if I hold the lever in and slide the action a shell pops out but the metal piece will not lift the shell up into the chamber ...so am going back to the guy I bought it from,he found me a key at work and will have him inspect it as he is the one that put it together......;)

Thanks guys ...

September 17, 2008, 04:52 PM
Well that's a new one to me to have to press the lever to chamber a rd,not sure what the purpose of that is

The "lever" is called the "action bar lock" by Remington and the "action bar release" by most folks I know. When you move fore arm all the way forward, it locks into place. There are 2 ways to "unlock" it from this forward posision

1)pull the trigger
2)press the action bar release

Without doing one of these 2 things, you will not be able to load a shell from the "fore arm forward" position.

Here is a pdf of the manual for your gun:

Your mossberg cruiser had a very similar part, except that I'm pretty sure Mosberg puts them towards the rear of the trigger on the left side instead of in front like Remington does.

Keep in mind that you will not have to push the action bar release every time you want to move a round into the chamber. If you are shooting the gun, simply pull the trigger and pump. You can repeat this action until the gun runs dry without touching the action bar release.

As for the J-lock issue, there are parts you can get to replace it. I don't know what they are, but you should be able to find them with a search. Horrible idea that thankfully the company has done away with.

September 17, 2008, 05:02 PM
You can dry fire it with no problems------was more concerned with pulling the trigger with an unknown chamber condition.

September 17, 2008, 05:15 PM
O.K. well thanks waterhouse,I just do not remember having to do anything like that on my mossy ....not that it means alot that I forgot...lol

Still not sure why the shell is not being lifted / pushed up into the chamber ......when I slide the pump back the shell extracts from the mag onto the "ramp" and when I slide the action forward to chamber it just tries to slide back in the mag,I have to push up on the ramp to get it chamber.....will be going to the sellers place tomorrow to get the key so will let him check it out.

But I do have a bit of gun porn for ya guys...:evil:


September 17, 2008, 09:57 PM
A buddy of mine had a similar issue with his 870. On his one of the action bars was slightly bent.

September 18, 2008, 08:59 AM
Nice looking gun! I have always been partial to Marine pumps, I might have to pick one up someday.
If the weapon is cocked (slide racked already) the slide will not move unless you press in that lever you are referring to. So you can either dry fire before loading the mag (make sure you check the hole before doing this of course) so that you will have control of the slide or just push in that lever to chamber a round after the tube has already been loaded.


Fred Fuller
September 18, 2008, 09:33 AM

I take it we are clear on the function of the action bar lock at this point, so I won't belabor that one.

Sounds as if there could be some sort of binding or other problem with the carrier dog, follower or spring. Those are the parts which are supposed to lift the carrier up as the action is closed so that the bolt feeds the shell into the chamber.

Will the carrier go up as the action is cycled when the gun is empty? Or does it only have this problem when there are shells in the magazine?


Mike U.
September 18, 2008, 08:48 PM
I think Lee Lapin may well have the answer.

But, if it doesn't work:
I've zoomed in on your picture and it looks to me like that idiot-lock on the safety is in the UN-locked position. Your action bar appears to be in the activated position. Make sure there is no round in the chamber, go out, safely aim the shotgun and dry fire it ONLY after your sure the chamber is empty. You will then, hopefully, be able to chamber a round.

September 21, 2008, 07:54 PM
I believe it would be the safest approach to never consider the dry-fire as a motion used to free the action slide. Technically, it will work, if the parts operate properly, but if the parts already operate properly, WHY?
The less that an operation is performed, the less chance that the hammer is dropped without the intention of a shell being fired.
I could shut off my engine by popping the clutch in high gear, but is that a prudent approach? The key is there for a reason, and so is the slide release. The trigger is not a slide release.
It is a firing lever.
If the slide will not operate with the slide lock/release being actuated, firing the trigger is not a viable solution, except in dire circumstances when you have no other options open to you. Even then, it is unlikely to render the gun back to firing condition. That is when you might revert to the buttstroke to the adversary's jaw, or else run like heck.
Practice sessions or action checking with live shells in the vicinity is best considered verboten. Practice safe gun function tests. Do not investigate malfunction possibilities with ammunition.

If you insist on having the gun able to stroke and load the chamber by pumping without use of the slide lock/release, dry fire the gun when totally empty (verified) and THEN load the magazine. Ready to rack-n-roll, now.


September 22, 2008, 08:46 PM
Well turns out the pins used to install the sidesaddle shell holder were binding up the action for the carrier,removed them and replaced with new pins and she is smooth as glass.

Man what a sweet action this shotgun has,now back to the range to actually shoot it this time and put this knoxx stock to the test....:p

Thanks for all the info and help ...

Mike U.
September 22, 2008, 10:19 PM
DOH!! :uhoh:

Doncha hate it when that happens?! Glad you found the problem.

You just made the case for why side saddles are a baaad idea. This could apply to other after-market goodies we like to mount on our shotguns as well.

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