Mossberg 500 quirk, dangerous or blessing?

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Inhimwelive

New member
Alright I have a Mossberg 500 that I bought new over 30 years ago.. This gun has taken more then its share of deer and turkeys.. But the thing is its developed a weird quirk. It auto ejects the spent shells. You take a shot and the slide goes back and most of the time kicks out the spent shell. Anyone seen this before? I can't see a danger in it am I missing something?
 
Well, its not supposed to unlock and open itself when fired. Some part of the locking system is worn.
You may not see a danger in it, but a little more wear, and it may open even earlier. Once it opens before the shot charge leaves the muzzle, you will find a danger in it.
Although, it will be too late then.
It needs the attention of a gunsmith.
 
Really? So you think it will eject the shell faster then an autoloader?
Click to expand...
What he is alluding to is the bolt unlocking too early, and being rocketed to the rear of the receiver by the pressure in the barrel. In the process, significant damage to the firearm can occur, the shell is likely to rupture (possibly injuring you or someone near you), and any hands or fingers in the way of the fore stock will get slammed, smashed, pinched, or worse.

Get it looked at.


It's possible that there may not be a problem. Heavy loads and/or loose grips tend to let pump action shotguns unlock themselves under recoil.
 
I read on another forum where a guy had a new 870 that was doing what you describe..The forearm was being ripped from his hand when he shot.. That is not what its happening with mine..I don't even notice the forearm going back until after I've shot.. The parts in the gun are all pretty basic to remove and replace.. What parts restrict this?
 
Mossberg quirk

Check you bolt lug recess in the barrel; The bolt lug may not be fully engaging in the recess due to dirt, crud, etc.
Worth a look. Happened to me with my 20ga. 500; Scared the Hell out of me.
WILL
 
The bolt is likely not engaging the barrel right.

Using the slide, when you pull on the slide, the first thing is the bolt drops down out of the barrel.

With the cartridge pushing back, the bolt lug is held firmly in the recess.

So, what you are saying sounds like the lug is not being held in the barrel well. This is dangerous as has been noted.

On the other hand, I've seen this as shooter induced.
 
On the line of this being shooter induced I was thinking I could test that out.. I figure if I shoot it with out holding the forearm it would not do it if its shooter induced. But on the other hand it would still do it if its a flaw in the gun.
Make sense?
 
The front of the action lock lever might be worn.
On the Mossberg schematic section at Brownells.com web site, it's part number 3.
It does make rapid fire a lot faster.
 
No that line of thought does not make sense.

When the gun is fired the action is unlocked, the weight of the forearm will cause the action to open during recoil.

Do this with the gun unloaded, put a long dowel down the barrel, press the dowel against wall or door frame. Then pull the trigger and drop the hammer, the action should stay closed. If the action opens as you press on the dowel rod before pulling the trigger-- time to see gun smith.
 
It could be that the action lock bar in the trigger group is slightly worn or the bolt slide (if that's what the piece the bolt rides on is called) is slightly worn. That's the piece that tips down when the action release lever is depressed. A fellow's locked/unfired .410 Mossberg 500 could be unlocked by racking back the slide (and no depressing of the slide release). It was that bolt slide that was poorly casted. It should never have left the factory. Mossberg was good enough to exchange that part for free (he had to pay postage to send it to Mossberg though).
 
Gary, either that, or the spring on the outside of the magazine tube. I'm not sure how hard he pressed the dowel in, but he said it held, and since it uses friction to lock it, it could be any of three parts, the button, the action slide, or the forearm spring. If it takes mild pressure to lock it, I'm betting the spring is collapsed, or there's rust between the spring and the magazine tube.

An easy test is just to apply a bit of reward pressure to the forearm, then drop the hammer. It should stay locked until you release the pressure off the forearm.
 
Inhimwelive,

Since it held, I would look at the Action Slide Spring. Below is a photo of one from Numrich. To get to the spring, you have to remove the action slide/forearm from the magazine tube. The spring is on the outside of the magazine tube, and is hidden underneath the action slide.

I would look for the spring to be compressed over age, or maybe stuck with rust, etc., so it can't push against the inside of the action slide/forearm.

A lot has to do with how one holds a shotgun like the 500, as if you do not pull backward on the forearm, while holding the gun against your shoulder, and the action slide spring does not push back the action slide, the gun can fly open when firing, as there is no pressure to cause friction between the bolt slide, and the action lock lever (lock button). Some shoot by just resting the forearm in their hand, but put no rearward pressure on it, so they added the spring to compensate for that missing pressure.

If the action slide spring is pushing back, as it should, and the breech opens, then the action lock lever, or the bolt slide is worn, and would need replacing. Under no circumstances, should the action lock levers button go up on its own, as if one had pressed it, by just dry firing, and letting the hammer fall. After letting the hammer fall, one should have to slightly pull forward on the forearm, first, for the button to go up, and allow the breech to unlock.



802790.jpg


Copyright Numrich Gun Parts Corp.
 
DG - for the life of me I don't recall seeing a spring like the one you depicted on a Mossberg 500 or 590.

I'm going to have to think about it overnight. The bolt should remain locked up while the action slide (part #3) is forward. It only goes back once the action slide is allowed to move back and that is when the the action lock lever (part #59) is depressed or if the bearing surface between the action lock lever and the action slide is worn.

Go to Guns Parts catalog and find the parts diagram.
 
That spring is on early versions of the 500...
Mine used to have it. Honestly, it didn't have much effect on functioning at all.
When I put on a new mag tube, it did not have the spring.
Myself, I try to maintain forward pressure on the forend when firing to help with recoil control. My 500 has never opened even a little on firing.
 
I'm thinking that the action lock spring is too worn or lacks the strength to hold the action locking bar up. The sharp recoil may allow that spring to let the action locking bar to slip, thereby freeing the action locking bar to drop and the bolt slide to disengage the bolt.

Hard to say without seeing and examining it.
 
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