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DPMS .308 failure to feed

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  • DPMS .308 failure to feed

    DPMS lr.308...When using either ballistic tipped ammo or softpoint, the cartridge gets snagged feeding into the chamber right at the tip. Bolt ends up beside the cartridge instead of behind it. This is a recent development. Has been shooting all ammo fine until now. Have cleaned and recleaned and am attempting different lubes. A friend suggested an adjustable gas block but I think the issue is short stroking. By lowering the gas flow, i would think it would be worse. At a loss...anyone run into this and what was your fix?

  • #2
    Does the bolt lock back after the last round ? Have you tried different mags? Have you cleaned and oiled your mags lately ? If this is a new problem and it use to feed ballistic tips and soft points then suddenly stopped I would suspect a magazine problem , maybe bent feed lips ?

    As a after thought is this factory ammo or reloads ?
    Last edited by pcj; 10-01-2018, 20:01.

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    • #3
      Most of the above questions, although I NEVER oil magazines.
      If I ever lube one, dry Teflon or dry silicone.

      Clean yes, oil never.

      how far and what direction is ejection?

      LR308s, ESPECIALLY CARBINES, are badly badly overgassed, yes, they can move so fast that they outrun a perfectly good magazines ability to feed properly.
      Same thing in M4 carbines until they put super heavy buffers in to slow them down.

      .308 shoves 2x as much gas at a higher pressure down a barrel with only 1.5x the volume of the .223 barrel so that pressure stays higher longer.

      AR15 rifles are overgassed slightly for reliability when dirty.
      AR15 Carbines are overgassed to the point of unreliability until they weighed the buffer down, LOTS.
      .308 ARs are worse on both counts if using wide open gas blicks.

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      • #4
        On ejection, is it denting brass on the deflector or not (indicator of high/excessive bolt speed).

        Also, ANY gas leakage around the gas block?
        A loose block bleeds and they short stroke.
        A short stroke can eject but not come back far enough to strip a round.

        Winter 16/17 I spent 4 months building an 18" LR308 rifle.
        I spent the entire time scouring the internet not for parts, but for problems they have, then making parts decisions to solve/prevent those problems.

        Mine has been 100% but runs an adjustable block, steel, clamping style, no setscrews, standard weight buffer and springs.

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        • #5
          Looked at the gas block and found a couple of issues. First, it was loose.Both set screws weren't even finger tight. Got an adjustable gas block w/vent. When attempting to remove the DPMS block, it appears when it was assembled at the factory the block was originally installed upside down and one set screw tightened. Once the guy saw it was upside down, rather than loosen the tightened screw he just grabbed it and spun it around leaving a significant gouge in the machined portion. the scratch was not in a position to interfere with the gas hole or tube so I was able to file it down smooth. It was bear to get off. Now it slides on as intended. After adjusting the block, it runs better than new. So in conclusion, I very much appreciate your troubleshooting skills. Maybe just tightening the block would have fixed it, but I have now added a compensator/flash hider with directional ports and adjusted the block for the least amount of gas to operate and am completely thrilled with the result. A .308 that has little to no muzzle rise and the recoil of ar15. Thanks

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          • #6
            Gotta love when the factory guy dorks up your barrel new.
            Yes, best to remove any raised burrs from the setscrew gouging or you are begging for gas leakage.
            Keep a close eye on those setscrews on that block, red locktite is a good idea.

            the barrel does have either 2 flats or 2 light divots for the setscrews to bite on, yes? It should.

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