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Help!! 930 wouldn't cycle 3" shells

Discussion in 'Mossberg 930 Autoloader' started by Yanger, Oct 27, 2018.

  1. Yanger

    Yanger .22LR

    Messages:
    11
    Hi everyone,
    I have a very confusing problem.
    I brought this 930 used. The gun can cycle 2 3/4 shells no problem.
    I have tried 7 1/2 target load, buckshots and slugs. The gun cycles them no problem. However once I start using 3" waterfowl shells it would not feed them from the magazine. I have rounded and polished the shell stop following the brownell article. I can manually cycle the 3" shells without problem.
    I have done the following tests
    Chamber 2 3/4" and 3" in the magazine that would cycle.
    Chamber 3" and 2 3/4" in the magazine that would cycle.
    Chamber 3" and 3" in the magazine that would not cycle.
    The magazine is plug for only 2 rounds and I have tried taking out the plug and filling up the magazine with 4 rounds of 3" still wouldn't cycle.

    The magazine tube doe have a few light marks on it.
    I'm wondering is my next step to replace the magazine or keep trying different ammo hoping the gun will find one it likes and cycle it??

    Any advice or suggestions would be greatly appreciated

    Andy
    meanstreak likes this.
  2. John A.

    John A. I'm "THAT" guy Staff Member Global Moderator Moderator

    Messages:
    13,793
    Does the shotgun seem to be cycling very hard with the 3 inch shells? Since you said you can manually cycle/chamber the 3 inch shells, that would appear to show that the chamber will accept them without a problem.

    Reason I ask how the gun is cycling is I wonder if the previous owner may have replaced the factory spring with a lighter one and am wondering if it's battering the bolt and cycling too hard.
    meanstreak likes this.
  3. Yanger

    Yanger .22LR

    Messages:
    11
    The 3" has harder recoil than the 2 3/4" but I don't find it abnormally harder than say buckshot or slugs.
    I want to add that extradition is very good.
    The 2 3/4 or 3 shells will fly out and land 3 to 4 feet away.
    Could the problem be the bolt is going so fast and hard that it doesn't trip the shell stop leveler?
    meanstreak likes this.
  4. John A.

    John A. I'm "THAT" guy Staff Member Global Moderator Moderator

    Messages:
    13,793
    I wouldn't be able to guess, but is something that I would check.

    I have a Charles Daly MaxiMag 12 gauge that I have replaced the main spring in order to get it to cycle 2-3/4 inch shells since they're mainly what I use.

    The shotgun is actually set up for 3 and 3 1/2" shells, so it definitely had a strong spring originally and was just too strong for the 2 3/4's. So, I used a lighter spring so it will allow the weaker shells to cycle the bolt properly.

    I know with other guns, if the spring is too light, will also cause feeding problems. As well as battering the bolt and receiver. And with your 930 being used, it's untelling what has been done to it by a previous owner.

    I'm only speculating what it may be.
    meanstreak likes this.
  5. Yanger

    Yanger .22LR

    Messages:
    11
    Thanks for the suggestion.
    So my options are
    Mag tube replacement and recoil spring replacement.
    I'm wondering if there is anyway to adjust the secondary gas system?
    meanstreak likes this.
  6. OR3GUN

    OR3GUN Sponsor Sponsor

    Messages:
    203
    The secondary gas system doesn't really have any way to adjust it, unless you have access to specialized tools and springs from earlier versions.

    It is very likely the magazine spring. The heavier shell column is being pulled away from the shell stop (and proper feed timing) under the heavier recoil of the 3" loads. Make sure you are solid behind the gun and have a strong magazine spring and your problem should go away.

    William

    http://www.OR3GUN.com
  7. Yanger

    Yanger .22LR

    Messages:
    11
    Hi William
    thanks for the input
    Would you recommend I try to push the cap retainer farther in or try stretching the spring to create more spring tension?
    meanstreak likes this.
  8. OR3GUN

    OR3GUN Sponsor Sponsor

    Messages:
    203
    Bobster, meanstreak and Djcala like this.
  9. Yanger

    Yanger .22LR

    Messages:
    11
    Spring ordered
    I'll report back once install it and see if it solve the problem
  10. Yanger

    Yanger .22LR

    Messages:
    11
    Update:
    I installed the spring and trimmed it to 13inch pass the tube.
    I can only get 4 rounds in vs 5 round from the stock spring ( I'm okay with that since I use a plug for hunting)
    Still get the same problem.
    Any other suggestions?
    I'm going to buy only 2 3/4 from now on but still boggles the mind why it doesn't cycle 3"
  11. John A.

    John A. I'm "THAT" guy Staff Member Global Moderator Moderator

    Messages:
    13,793
    Are the shells not going in the magazine tube, or are you having a problem with the gun cycling them and functioning?

    Are you having fail to feed, fail to extract, fail to eject?
  12. Yanger

    Yanger .22LR

    Messages:
    11
    None gun works very good but only with 2 3/4
    Once I use 3" it wouldn't feed
  13. John A.

    John A. I'm "THAT" guy Staff Member Global Moderator Moderator

    Messages:
    13,793
    That is odd, especially since I hear more complaints being the other way around.
  14. Rob972

    Rob972 Copper BB

    Messages:
    7
    Ok, "doesn't feed" is not specific enough. Do you mean that 3" shells do not eject from the magazine onto the loader at all, i.e., you fire the chambered round and the bolt locks open with rounds in the mag, or the bolt closes with no round sent to the loader?

    Does a round get on the loader, but doesn't get chambered?

    I am assuming it's one of the first two...

    I'm not affiliated with William, but can recommend his products. If your problem relates to bolt return, OR3Gun's ASR/CSP combo will probably offer a solution:
    http://www.or3gun.com/OR3GUN/about_or3gun_plunger.htm

    A couple of other thoughts:
    Your mag spring can also be too tight. E.g., you can load to capacity, but the tension from the spring, to the shell, to the shell latch, is too great to allow the latch to release, with the faster action of the 3" rounds. The rounds in the tube have forward and back motion with the firing action. With snappy loads, you need to hit the sweet spot between reliable feeding and a spring too strong to release.

    I used a brake-hone and 3-in-1 oil to polish the inside of my mag tube, and a green 3M Scotchbrite pad, with oil on a section of cleaning rod, to polish the action spring tube.
  15. Yanger

    Yanger .22LR

    Messages:
    11
    When I fire a 3" shell
    The bolt will slide back and forth into battery but no shell will come out of the mag.
    I have already polish the release and can manual cycle the shells.

    Thanks for the suggestion
    I'll try to ploish the tube
    I'm not sure if I should trim the wolf mag spring anymore..
  16. Rob72

    Rob72 .410

    Messages:
    41
    I'm going to suggest that your bolt speed is the issue. OR3Gun's crew has more varied experience than I do, so I defer to their recommendations, but it sounds like the bolt is either bottoming out in the receiver, or cycling back just enough to eject, but possibly not engaging the shell release.
  17. OR3GUN

    OR3GUN Sponsor Sponsor

    Messages:
    203
    If you have a fairly modern smart phone you should be able to record video of the gun cycling and watch it back in slow motion. Get 100% solid behind the gun in a very aggressive stance and see if the cycling improves. Often with 3" shells it is the recoil messing up the timing of feeding the next shell. If it feeds by hand, but isn't feeding under firing it is more than likely that the shell is not at the shell stop where it should be due to recoil. A stronger magazine spring usually fixes it, but even if you have to park the recoil pad against a tree, rule out movement of the gun affecting the shell column under recoil before trimming anymore on the spring.

    William

    http://www.OR3GUN.com
    nitesite likes this.

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