Hello everyone, I have a 22" JM Pro shot gun that I'm having an issue with. I'm not sure on my terminology; so I'm going to describe what's happening and then you can tell me what the parts are called so I can figure out what's going on. First thing, I love the shot gun. This is my first shot gun purchase and I find it very light and the butt stock is super soft. I found one in PA so I bought it and had it shipped to my local FFL. Pulled it out and took it to the range.

So far I've fired buck shot and 7 1/2 out of it without issues or complaints....now onto my issue.

I pull the bolt to the read to ensure the chamber is clear (old army habit, but one I always practice) and it locks into position. With the bolt to the rear, you can not load the shot gun because the (unknown part) feed door doesn't swing freely. If you push hard enough, the bolt rides forward towards the chamber and then the door swings freely. You can also push the bolt release button (I'm calling it) towards the bottom of the shot gun to release the bolt forward...And here enlies my issue. SOMETIMES (not all the time or continuously repeatible) when I push the bolt release button, the feeder door swings ALL THE WAY UP into the chamber area and the bolt slams against it. The door stays stuck inside the area and the only way to release it is to retract the bolt, back into the locked position, turn the shot gun upside down and depress a "bar" that is on the left side of the shot gun.

I'm not sure what that bar is for, because when I retract the bolt and depress the bolt release button; it doesn't release the door. I have even gone as far as holding the button down and the bolt back to see if the door just "falls" back into position, but that doesn't happen. What I usually have to do is retract the bolt, turn the shot gun upside down, depress the bar, let the door swing down and then release the bolt so I can load the shot gun. I do not recall if this happens after I've fired through it or just when I'm trying to make sure it's clear and load it. But either way it's pretty annoying and I'm wondering if anyone has experienced this before.

Here's what I've done.

Bought it monday, took it to the range on the way home. Fired 10 slugs through it. Got it home and rodded the barrel and cleaned everything I could see (No, I didn't take it apart). Next week, took it to the range and fired about 25 71/2 through it. Took it home and cleaned as before. Was playing with it at the house and noticed that it did this jamming thing. Was practicing loading and unloading and when I hit the button it jammed. messed with it until it came loose. Next weekend I took it to a friends house and put 25 71/2 through it. After 8, and I was trying to load it it did the same thing; but I'm not sure if I had the shot gun sideways or not (Laying on its side as opposed to sights up) when the jam occurred.

A few days ago, I took the shot gun apart, as far as I felt comfortable doing and cleaned it. Put the bolt to the rear and dropped some CLP onto the face and scrubbed it with a tooth brush. Took off the cap for the loading chamber and cleaned that as well. I have not taken it apart as far as it will go though; but can as long as I know what to do (a really good manual) so I don't mess it up.

Does anyone have any ideas on why this may be happening? I can't duplicate the issue and I've tried, so I can call Mossberg and ask them why it may be doing this. Thanks for the help and hope to hear from someone soon so I can make sense of it.

I appreciate your info. This has only happened 2 times so far and I haven't had a chance to research it yet; and since I didn't know what the items were called, I didn't really know what to search on.

I had this same problem with mine. I had cleaned and oiled the gun well before the first firing and had no problems on the first go round. The problem came later on the second go round which I think was due to shouldering it to softly and using some older ammo that I had (possibly). I found that I could recreate it if I had the bolt locked back and the pressed the release while loosely holding the gun with one hand, further making me believe that it was weak shouldering on my part.
I did not think that this was acceptable because when I through the gun up some times I don't have it in the pocket like I should.

My solution was to knock down/ radius the edge of the elevator that was snagging on the bolt release and holding it up. This is what I did and recommend that you only do this if you are willing to accept to possibility of a making a mistake.
Never the less I can now firing the gun as loosely held as I want from the hip and it cycles well. I also shot the faster stuff that is low brass bird shot, 75 rounds and no hiccups.

YMMV