Mossberg cycling issue

[forrestd]

I was out shooting clays this past weekend, and toward the end the Mossberg started having some trouble cycling. It would get a little bit jammed up when the action was all the way back but eventually it'd give way with enough persuading. This didn't bode well for me since it pulls double duty as a bedside home defense gun, so I took it apart and here's what I found.

The lug on the bolt shows pretty uneven wear:



Here's another angle:



And here's the inside of the receiver (barrel to the left, butt stock to the right):


Has anybody seen this? I can certainly take more pictures if it'd be helpful in diagnosing the issue. Thanks.

 

[Pete409]

I can't tell much of anything from the third picture, but the second picture shows a bevel on the top rear of the locking lug. Perhaps a side view of that locking lug would tell us more.

Here is the important part as I see it. The locking lug should lock firmly into the recess in the barrel extension. That is what keeps the bolt from flying rearward when the gun is fired.

Examine the size and shape of the locking recess in the barrel extension. Then compare that with the size and shape of the locking lug that is supposed to fit into that recess. In my opinion, it is the REAR portion of the locking lug that is most important because that is the portion that is in direct contact with the recess in the barrel extension during the firing of the gun to prevent rearward movement of the bolt.