M4 - AR Question

M4 - AR Question

This is a discussion on M4 - AR Question within the Defensive Rifles & Shotgun Discussion forums, part of the Related Topics category; For all of you M-4 gurus I have a problem I can't seem to resolve. On my DPMS suddenly the buffer retainer slips off the ...

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Thread: M4 - AR Question

  1. #1
    VIP Member Array Ridgeline's Avatar
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    Question M4 - AR Question

    For all of you M-4 gurus I have a problem I can't seem to resolve. On my DPMS suddenly the buffer retainer slips off the spring and down into the trigger assembly. This will not only happen in live fire but also when charging the weapon, not every time but often enough I would not grab this long gun in a problem situation. Any ideas what could be causing this would be appreciated. And yes it is clean and no it is not dry.
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    Distinguished Member Array Siafu's Avatar
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    Is the buffer retainer pin in spec? Possibly a broken tip? What about the buffer? Is it in spec? Do you have a commercial buffer or a mil-spec? I am not sure if they have the same ID but I do know they have different OD's. How long have you had your rifle before this problem manifested?

  3. #3
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    Is the buffer tube threaded far enough in to cover all but the tip of the retainer pin? Are the threads in the lower (both buffer tube and retainer threads)in good shape or worn ?
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    Quote Originally Posted by rocky View Post
    Is the buffer tube threaded far enough in to cover all but the tip of the retainer pin? Are the threads in the lower (both buffer tube and retainer threads)in good shape or worn ?
    +1.......It the buffer tube screwed in far enough? It probably needs one more turn....
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    BAC
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    Add mine as second vote for rocky's suggestion to check and see if the buffer tube is screwed in enough. The only other reason I could think of for it doing that would be a piece of the retaining pin to have chipped off and only barely be held in place.


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    Quote Originally Posted by BAC View Post
    Add mine as second vote for rocky's suggestion to check and see if the buffer tube is screwed in enough. The only other reason I could think of for it doing that would be a piece of the retaining pin to have chipped off and only barely be held in place.


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    Thinking the same thing.

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    Your buffer tube holds the pin in place. It should be screwed in just until it is ready to touch the pin the holds the buffer in place. You didn't mention it but have you or anyone replaced the stock, or had it tore down for service of some sort? Funny it would "just start" doing it, but if you have not fired it much since you got it, might be the case it just had not been used enough to get it worn loose. Prolly 1/2 to 1 full turn should do it. Don't forget to pull it apart and drop another cpl drops of locktight in the threads as well.......
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    +1

    Quote Originally Posted by rocky View Post
    Is the buffer tube threaded far enough in to cover all but the tip of the retainer pin? Are the threads in the lower (both buffer tube and retainer threads)in good shape or worn ?
    +1 look at it
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    +1 on turning the receiver extension in 1 more turn... But don't lock tight it. The TDP calls for staking the endplate to the castle nut for a reason - if you're gonna have to work on this end, you might as well put it back together correctly.
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    DPMS factory tocktights thier buffer tubes......its up to you if you decide not to, Personally, I always lock tight my buffer tubes.... they take alot of punishment....
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  11. #11
    Senior Member Array KevinDooley's Avatar
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    Given that this happens when a RE is locktite'd instead of properly staking the end plate into the castle nut:

    Help! - Oly crash & burn... :0( - M4Carbine.net Forums

    I'd say take the 2 minutes out of your day and stake the end plate - but hey, if you like playing gunsmith when the thing eventually backs off - more power to ya.

    More info here:

    Castle nut staking, why the big deal? - M4Carbine.net Forums
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  12. #12
    Member Array ibesarcasm's Avatar
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    If my weapon has threads......it has locktight, never said I don't stake the plate, just don't put it together without something on the threads.....
    that goes double for my handgun grips......... :)
    But then I am a pretty good smith, and I like to smith my guns......
    Just with I could do the bigger stuff instead of paying..........
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