Please help me fix my Mossberg 500

mmtecg · December 1, 2009, 08:17 PM

My Mossberg 500 (C model I think) has a serious problem that prohibits me from shooting with much pleasure at all.

The best way to describe the problem is to say that once, and only once a shell has been fired, the forearm stays locked and requires manual depression of the button behind the trigger guard to cycle another round.

This is not the case when dry-firing empty hulls. I can fill the mag with empty hulls and cycle, and dry fire them all without having to use the "button".

What is it about firing a shell that somehow does not raise the button.

I have removed all internals (except disassembling the the trigger group) and used a buffing wheel and steel compound to polish all internal parts. I then installed all parts according to this http://www.youtube.com/watch?v=oKbWcPdTRBI video, and I was left with the same result.

Please help.

Thanks, Michael

the rifleer · December 1, 2009, 09:25 PM

do you have the two bars on the side? (not the action bars connected to the forehandle) I'm not sure of the names, but make sure you have them installed correctly. they are directly above the bolt and go to the magazine tube. the curved side points inward. if they are incorrectly installed then that could cause the problem.

Also worth noting- the mossberg will lock itself shut when you shoot it and not allow you to pump it while its loaded/cocked. It will not unlock until you relieve the pressure on the forearm. So try (unloaded again) to cock it, then hold it exactly the way you do when shooting and dry fire it. then jiggle the forearm. it should open up instantly. if it doesnt, have it checked out by either a gun smith or someone who is familiar with it.

mmtecg · December 1, 2009, 09:31 PM

Thanks for the reply. I took it apart again to see if I could see anything I had not seen before and my dad pointed out that one of the side bars (I don't know the name either) had a burr on the tip of it. I used a dremel and a grinding stone and brought it down smooth again, put it back together and it works fine.

I only shot two shots (it nighttime) but it seemed rack and fire properly.

Thanks, Michael

December 1, 2009, 08:17 PM	#1
mmtecg Member Join Date: August 15, 2009 Posts: 26	Please help me fix my Mossberg 500 My Mossberg 500 (C model I think) has a serious problem that prohibits me from shooting with much pleasure at all. The best way to describe the problem is to say that once, and only once a shell has been fired, the forearm stays locked and requires manual depression of the button behind the trigger guard to cycle another round. This is not the case when dry-firing empty hulls. I can fill the mag with empty hulls and cycle, and dry fire them all without having to use the "button". What is it about firing a shell that somehow does not raise the button. I have removed all internals (except disassembling the the trigger group) and used a buffing wheel and steel compound to polish all internal parts. I then installed all parts according to this http://www.youtube.com/watch?v=oKbWcPdTRBI video, and I was left with the same result. Please help. Thanks, Michael

December 1, 2009, 09:25 PM	#2
the rifleer Senior Member Join Date: March 5, 2008 Location: Sunny California Posts: 1,281	do you have the two bars on the side? (not the action bars connected to the forehandle) I'm not sure of the names, but make sure you have them installed correctly. they are directly above the bolt and go to the magazine tube. the curved side points inward. if they are incorrectly installed then that could cause the problem. Also worth noting- the mossberg will lock itself shut when you shoot it and not allow you to pump it while its loaded/cocked. It will not unlock until you relieve the pressure on the forearm. So try (unloaded again) to cock it, then hold it exactly the way you do when shooting and dry fire it. then jiggle the forearm. it should open up instantly. if it doesnt, have it checked out by either a gun smith or someone who is familiar with it.

December 1, 2009, 09:31 PM	#3
mmtecg Member Join Date: August 15, 2009 Posts: 26	Thanks for the reply. I took it apart again to see if I could see anything I had not seen before and my dad pointed out that one of the side bars (I don't know the name either) had a burr on the tip of it. I used a dremel and a grinding stone and brought it down smooth again, put it back together and it works fine. I only shot two shots (it nighttime) but it seemed rack and fire properly. Thanks, Michael