Mossberg 500AG firing problem

[Aderondacker]

Hello Everyone need help with this one!!! Mossberg 500AG 12 ga. 1983 Mfg date.
Problem is that the gun fire’s when the pump is slid forward. I have taken the trigger mechanism apart cleaned and reassembled. The sear and hammer are good, the disconnector appears to be good but I suspect this to be the problem. When testing the trigger assembly out of the action, the disconnector moves freely and moves away from the sear when the trigger is released. When I manually cock the hammer, I have good contact between sear and hammer. I believe the problem is when the bolt goes forward the disconnector rises up and causes the shotgun to fire. I adjusted the trigger stop screw so the disconnector moves all the way to the rear. I open the action, wiggle the trigger from side to side (the trigger doesn’t move forward or backward so the disconnector doesn’t move rearward). The hammer stays cock when the pump slides forward. The problem is intermittent. Something is hanging up; anyone have a similar problem with the shotgun firing with your finger off the trigger when the pump is slid forward. Thanks John

 

[Aderondacker]

I believed I solved the problem. The hammer releases just as the bolt locks up. I’m going to replace the sear and hammer instead of trying to hone new surfaces. $40.00 and piece of mind. If I work the action gently the hammer stays cocked. Normal force in closing the action causes the hammer to slip off the sear. If the hammer was not being held by the sear and following the bolt when the action is being closed, I don’t think the shotgun would fire. Not enough force to dent the primer. The hammer is being release just as the bolt locks up causing it shotgun to fire. Under strong light these old eyes can see a flash and the hammer appears as the action closes. John

 

[toolman846]

" I have taken the trigger mechanism apart cleaned and reassembled. "

I earlier posted a thread asking for any help on an older 500AB I'm trying to resurrect for a present to someone, and I too, took the trigger mechanism apart, both to clean years fo junk out of it, and to have all the metal parts black oxide coated. I can't find any reliable or clear pics of the trigger mechanism, to help me get it back together, and a call to Mossberg got the response they don't HAVE any pics of the older-style trigger mechanism, so they obviously don't want to help. I'm getting desparate, as the birthday is coming up, and I still can't figure out how to put it back togather, and don't know what book might have the right pics, of the older-style trigger mechanism, to help me. I should have taken a couple of pics of it before I took it apart, but it's too late now. Any advice would be greatly appreciated. Thanks.

Jim

 

[fixyurgun]

Toolman, have you looked at the gunsdigest volume 5 on shotguns? They have the step by step instructions on the mossberg.I'm not sure if it's the old style or not but maybe it will help. jim

 

[toolman846]

Thanks for the lead. After posting on several forums, it's the only response I've gotten, and I really appreciate it.