DK Firearms

Any guideance to help with .308 problem?

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  • popper

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    Over gassed & under lubed. Possible bad head space. Overgassed unlocks the bolt too early, when pressure is still high & beats the dickins out of everything. Rough lugs take more pressure to close and clean the metal shavings out. Improper HS can cause the same bolt problem but won't always beat up the rest of the gun. Check the lower for cracks at the BT. Hope you got it cheap.
     

    mitchntx

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    Hey look ... a thread about guns and shooting them instead of guns and carrying them.
    Awesome!

    Similar problems with a new BRO AR-10.
    My BRO doesn't have an assist, but I can just touch the BCG and it moves about 1/8" and works fine.

    Over 200 rounds down the pipe. Various grains and brands.
    Lugs on the BCG were polished and smoothed.
    Checked for drag with no signs.
    Used a variety of lubes from Frog to Mobil 1.
    Cleaned everything I could.

    Called BRO and was sent a 1" longer buffer spring.
    Helped, but not solved.

    I have scavenged a BCG from a DPMS that has worked perfect for years and will try that.
    I will report back.
     
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    popper

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    just touch the BCG and it moves about 1/8" and works
    What does the extracter look like? Gas tube position? Lock up OK without a mag? Bolt pin? Something is making it hang and the longer spring just acts like an FA. My DPMS take about 1/8" to click when the action is open, but that is the charging handle.
     

    ROGER4314

    Been Called "Flash" Since I Was A Kid!
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    I would change the ammo first before tinkering with anything else. Remember, the malfunction is the best clue to the problem so don't make the problem go away by making a lot of changes! Try one thing at a time and check the results.

    Flash
     

    mitchntx

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    I have scavenged a BCG from a DPMS that has worked perfect for years and will try that.
    I will report back.

    BCG from the DPMS had the same exact issue.
    BRO BCG in the DPMS operated flawlessly

    What does the extracter look like? Gas tube position? Lock up OK without a mag? Bolt pin? Something is making it hang and the longer spring just acts like an FA. My DPMS take about 1/8" to click when the action is open, but that is the charging handle.

    Extractor is stiff, but clean and operates fine. No marks on a freshly chambered round or on a spent casing. Never an FTE.
    Gas tube and gas block was verified in position and no marks on the key as the tube goes into the key hole.
    Bolt pin seated.

    A full pull on the charging handle will chamber and seat a round.
    That's the reason why a spring was thought to be the culprit.

    I put the can on it and the problem became every round, not just every 2nd or third round.

    Close inspection of the barrel lugs reveals a shiney edge at the face, like the bolt is dragging along the edge between the 5 and 6 o'clock lug.
    A bore light has to be held just right to see it. May be the culprit.

    At any rate, I called BRO and have a shipping label ready to send it back.

    Thanks for the help, fellers. I've learned a lot.
     

    Leper

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    Being it out to Fusion on the next range day and we will swap parts with mine and see what happens. It will be easy to get more eyes on it too.
     

    mitchntx

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    Spring was changed early on.

    Update ...

    So I called BRO on the 26th of June and discussed the issue with their tech.
    I explained the methodical process I travelled.

    He said, we need to get that gun back in here and get it fixed. Sounds like it might have a several contributing issue.

    Talked with BRO Monday the 7th and the tech explained what they found.

    The bolt rings weren't sealing properly. So they installed a new bolt and carrier.
    I noted to him that the bolt was extremely stiff. He said it almost siezed when hot.

    Once the BCG was replaced, it was way over gassed, so they installed an adjustable gas block.

    Ran 15 rounds in succession with no issues.

    Due here today. So about 2 weeks door to door with the July 4th holiday thrown in.

    I'll renstall the optic and zero at 100 yards and report back.

    I hate having an issue with a gun that requires a return to the manufacturer.
    But so far Smith and Wesson, Ruger, Springfield and now Black Rain has been easy to work with, although the time it took to door to door my XDs was a little annoying.
     
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    Leper

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    If you always use the same ammo, you can really tune that gas block and make it much better to shot.
     

    mitchntx

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    Update:

    Installed the can and every other round stove-piped.

    I figured the can was causing it to be over-gassed, but didn't have an allen wrench the size and length to reach the gas block.
    Took it to my local gunsmith closed the gas block down 4 clicks and she runs like a clock.

    Removed the can and it stove-piped.

    I ran out of time, but I'm curious if it can be adjusted to function with and without the can and not have to adjust the gas block.
    The 300 BLK I have operates with and without and no issues. is a 308 just that finicky?

    I'm also curious if the block can be adjusted to the point of it cycling subsonic rounds.

    Any input or do I just need to experiment?
     

    RetArmySgt

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    Took the rifle apart today and noticed a few interesting things. The threads where the buffer tube screw into the lower receiver had been damaged (completely removed) on two spots on the bottom. These lined up perfectly with two wear marks on the bottom of the bolt carrier. Guess the spring is not keeping the bolt carrier for moving rearward too far. Also, the edges of the buffer on the side where the bolt carrier touches it appears to have been "chipped" away. I'm assuming it should be completely smooth and flat.

    I asked the builder if it had the proper buffer spring and was reassured that it did. I'm thinking the answer is it does not. What does everyone think?


    You will either need a longer, stiffer spring or you can use Quarters in the end of the tube (before the spring goes it) and that should help with part of your problem. You might also want to try a heavier buffer.
     
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