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Would you consider this normal bolt wear

Discussion in 'Mossberg 930 Autoloader' started by Brett Grimm, Sep 20, 2018.

  1. Brett Grimm

    Brett Grimm Copper BB

    I bought this JM Pro this summer new and have fired around 400 rounds. I actually noticed this wear around 250 rounds. Doesn't seem normal to me and you can also see some damage in the receiver. Would like to know your thoughtd before I contact Mossberg about the issue.
  2. JohnR6464

    JohnR6464 Copper BB

    Mine has about a thousand rounds through it and looks similar maybe not quite as bad. The thing I see in your pictures... in the receiver.. it looks like some mounting screws are sticking too far into the receiver.
    It looks like they are worn... must have been hitting the bolt. You should take them out you shorter ones or take them out grind them down a little and put them back in.

    I'll try to send pictures this weekend of mine. My JM Pro came with shorter screws in the front and a little longer screws in the back. The shorter ones are made to go in the front so they don't hit the bolt.
    Scoop likes this.
  3. MikeD

    MikeD I'm Your Huckleberry Staff Member Global Moderator "Philanthropist"

    Hard to tell from the pics. If just the black coating is worn off I would call it good. If the metal is wearing away you have excessive wear.

    I agree with the previous post, it looks like you have some wear from the receiver screws.
  4. Bobster

    Bobster .30-06 Supporter

    PS: Before doing below check to see if the rear screws are shorter than the fronts and swap them if they are. If they are the same length, continue on...

    The arrows below point to the scope rail mounting screws that were hitting as mentioned above. Remove those two forward screws, clamp in a soft jaw vise and file or grind a thread's worth of metal (.020"?) off and reinstall with Loctite after checking that you ground off enough. Clean any sharp edges created on the bolt with a jeweler's file, taking care not to let the filings get anywhere they shouldn't like inside the bolt or receiver.

  5. Brett Grimm

    Brett Grimm Copper BB

    Thanks for the info, it's just not the black finish coming off. There is physical wear to the bolt. I will check out the screws and report back. I post a couple more detailed pictures of the bolt wear.
  6. Pawpaw

    Pawpaw .30-06 Supporter

    The bolt cannot contact those front screws. When the barrel is installed, the barrel extension (or chamber extension, if you prefer) covers them.

    What can happen, if they're too long, is that they will deflect the barrel extension downward and the bolt can rub or even catch on the edge of the extension.

    Take a look at your barrel extension. I'm betting you will see wear where the bolt has been hitting it. The solution is the same... grind down the screws so they sit flush.

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