Mossberg 500 problem. Any thoughts?

Bojo · Mar 16, 2011

Hey all,

Recently purchased a used Mossberg 500. The firing pin does not contact the primer if there is any backpressure at all on the pump. I have to force the pump forward in order to make contact. This is not the case with any of the 500's I have owned before or own currently.

Based on the input of USN security details that I work with: when operating a Mossberg 500, one should be able to keep backpressure on the pump so as to "ride the recoil" into the next rack of the slide. So keeping a slight backpressure on the pump should not cause it to have a cat 1 malfunction. Is there something wrong with this one?

Any thoughts, tips, help would be appreciated.
Thanks,

-B

nubus · Mar 16, 2011

I have owned several, and that doesn't sound right to me.
Curious if anyone has messed with the bolt or the pin itself?
Also remove the barrel and make sure it is fully seated and tightly fastened.
A loose barrel attachment could easily cause this type of head-spacing issue.

Bojo · Mar 16, 2011

Trying it right now...
Thanks nubus. You're the man.

-B

Blitzkrieg · Mar 16, 2011

The nut on Mossberg barrels can be kind of rough to work with and cinch down fully.. good call, nubus

Bojo · Mar 16, 2011

After a detail stip and clean, it seems to be working via dry practice. Definately cranked down on that barrel nut. I'll try it for real this weekend. Thanks.

Bojo · Mar 21, 2011

UPDATE for anyone who cares: Took it out this weekend. SAME PROBLEM. Cat 1 malfunction. "Click" and nothing.
Decided to start swapping out parts with known-good parts from my other 500. The result?
I found that with a different Bolt Slide the problem went away. I have no idea why, but it started working with the bolt slide from my other 500. (I tested it using snap-caps and listening for the "Click-Pingggggg" sound.

Any idea where I can get a new Bolt Slide for a 500? Havlin Sales wants me to send in the Bolt so they can match it up, but I don't know why.

nubus · Mar 21, 2011

For SAFETY that's why.
Havlin is your best bet for all stuff Mossy.
They are very reasonably priced too.
Thanks for the follow up, to bad it wasn't easy.

Bojo · Mar 21, 2011

Ok, the decision is made then. Havlin it is.

I just never imagined that all the bolts and all the bolt slides arent already compatible.

Thanks again nubus.

RVTECH · Mar 22, 2011

Last summer someone gave me a box of assorted 500 parts. After cleaning everything I discovered I had parts for two complete guns (sort of - one has a cut off stock for the homemade Bubba tactical pistol grip look) but I put them together and it took some doing to get them to function properly. The ejectors were a nightmare to get adjusted correctly to properly get them to kick the shells out properly but more specifically it seemed I had a problem possibly related to what you are describing. One of them would not lock up completely when the the slide was forward. I cannot recall what I did to get it to lock up but it seemed to be related to the ejector adjustment. This is probably not much help but I really got an education in Mossy 500s putting these together.