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Mossberg 500AG firing problem

AderondackerAderondacker Member Posts: 5 ✭✭
edited October 2007 in Ask the Experts
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

Comments

  • MG1890MG1890 Member Posts: 4,460 ✭✭
    edited November -1
    Aderondacker -
    When I was doing this type of work for hire, guys would bring in lots of pump & auto shotguns that would not function correctly (NY slug guns get abused terribly). 98% of the time a complete disassembly and thorough cleaning would cure them. 1% of the time, I would actually see a faulty (broken) part. The other 1% would make me pull out my hair trying to figure out what was wrong. I found an easy method to isolate the problem. Simply borrow a similar shotgun, verify that the "borrowed" gun functions correctly, and begin interchanging parts, 1 at a time, until you find the problem. I would begin with the complete trigger group, then the bolt assy. Narrow it down 1 piece at a time.
    Hope this helps,
    Greg
  • drobsdrobs Member Posts: 22,620 ✭✭✭✭
    edited November -1
    Mossberg had a recall on their older shinny plastic trigger group / housing assembly. These were able to break if you pumped the slide too hard. Call Mossberg up they should send you out a completely new one.

    They did for me 5 to 10 years ago for my 1988 Mossberg 500.
  • AderondackerAderondacker Member Posts: 5 ✭✭
    edited November -1
    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. Thanks for your info and ideas. When I get the new parts, I'll let you know if Iwas correct. John
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