AR10 LR308 - Bolt Stuck in Forward Position

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  • DeanSports

    Plinker
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    0   0   0
    Oct 23, 2014
    48
    6
    Columbus
    I just built my first AR10 LR308.

    Took it to the range today and I couldn't get it to cycle correctly.

    It would chamber the round. Fire. But the bolt would not fire back. The bolt was stuck in the forward position.

    Before anyone says gas system issue. I don't believe it is.

    When I go home. I disassembled the entire gun. Got the casing out. Then just charged the round again like I did before, but I didn't fire it.

    The bold it still stuck in the forward position and had to disassemble it again.

    So I decided to only put the lower, the bolt and the barrel on. Same thing. Charge a round, cant get it to come back.

    The charging handle and bolt operate perfectly when there is not round to chamber. As soon as the round chambers, it is done. Has to be taken apart. A few time pulling as hard as I could I got it to release but other than that It's in there for good.

    [video]http://vid1146.photobucket.com/albums/o524/confidentialuser001/IMG_0801_zps3kmwtfj4.mp4[/video]

    Any help would be greatly appreciated.
     

    DeanSports

    Plinker
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    0   0   0
    Oct 23, 2014
    48
    6
    Columbus
    THere are factory. Just purchased them today. They are PMC Bronze.

    its actually all they had. First 308 I don't know what is good or not for a 308. 556 pmc runs great through my AR15.

    Is PMC a decent brand for 308
     

    churchmouse

    I still care....Really
    Emeritus
    Rating - 100%
    187   0   0
    Dec 7, 2011
    191,809
    152
    Speedway area
    Have you got after the chamber with a good solvent and a brush. Had this issue with AR's last summer. Chambers were dirty from the factory machining process.
     

    ROLEXrifleman

    Master
    Rating - 100%
    54   0   0
    Feb 7, 2009
    1,767
    84
    NW Indiana
    head spacing and chambers are two different things though both are related in the mechanics of the rifle. Who's barrel did you use?

    1) The barrel chamber may be cut tight. As you dont know what reamer was used it's a guessing game in that area.
    2) the neck of the cartridge may be getting pushed into the rifling. What does your cartridge neck look like after you extract it?
     

    rvb

    Grandmaster
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    4   0   0
    Jan 14, 2009
    6,396
    63
    IN (a refugee from MD)
    if it chambers easily it's probably not a headspace problem (w/ just the upper, remove the extractor, put a round in chamber, and under thumb pressure close the bolt. if the bolt cams over and carrier goes fully forward w/ just the pressure needed to over-come the ejector, it's probably not headspaced short. however, if it won't cam over it probably IS headspaced short and is only chambering under the full impact of the feed process.).
    From the vid, headspace is the first thing I'd suspect.

    It could be some other problem w/ the chamber, eg rough cut. inspect brass.

    you say you have to disassembe? a light motaring won't clear it? when I've seen this happen w/ headspace problems, either the gun or ammo, a light mortar will clear it easily.

    was just the bolt stuck and not the carrier? Or was the carrier stuck, too (eg would the bolt cam over easily, just not pull the case out)?

    -rvb
     
    Last edited:

    jwh20

    Master
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    28   0   0
    Feb 22, 2013
    2,069
    48
    Hamilton County Indi
    I have a friend with a Sig Patrol 716 that does this with certain .308 ammo. When looking closely you can see that the bolt locking mechanism, it doesn't rotate all the way to the in-battery position but stops just short. On his rifle, you can take a probe and push the bolt locking ring and release the bolt.

    It looks like, in his case, that the round doesn't quite go all the way into the chamber and this then blocks the bolt from getting all the way closed and the lock from engaging. The difficult part is that in this condition, the charging handle can't be used to pull the bolt back. So it appears to be stuck.

    My theory is that this is due to badly sized ammo. We haven't had a chance to try with some better ammo yet but all the ammo we were using was surplus ammo of unknown and mixed manufacture. Perhaps even some reloads.
     

    remauto1187

    Shooter
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    1   0   0
    Aug 25, 2012
    3,060
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    Stepping Stone
    If you dont have access to headspace gauges...Drop by a gunsmith and have them check headspace on the rilfe first. I would not fire this rifle anymore until headspace is confirmed.

    In general terms-- The headspace is the distance in between the bolt face and the head of the cartridge case. This distance if too large will lead to a blown up rifle because the pressure created when the gun powder is set off by the primer goes forward AND rearward and blows the head of the case off or splits the case or both and all that pressure is coming back to your face and can also destroy the upper and even the lower depending on the carnage. The distance if too small will jam the rifle up and typically either will not lock the bolt lugs into the barrel extension or will just lock up with zero wiggle room and is jammed up in the locked position. Both the bolt and barrel extension along with the chamber affect the headspace. Anyone of those out of spec will cause headspace problems (tight or loose).
     
    Last edited:

    Force10

    Marksman
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    0   0   0
    Feb 9, 2014
    192
    18
    Franklin County
    Hey DS, it sounds (as suggested by others) it is a chamber or headspace issue. If you don't have .308 go nogo gages, I do. Feel free to post up if you would like to borrow them! (I would PM ya, but your to "fresh" here to view PMs)
     

    DeanSports

    Plinker
    Rating - 0%
    0   0   0
    Oct 23, 2014
    48
    6
    Columbus
    Thanks for the feed back guys. I got it working correctly. First off I want to send Ares Armor major kudos.

    I told them about the problem and they offered to refund/ replace every item that has to do with the problem described. They even went as far as to build one there too see if the same problems happened and gave great suggestions like you guys.

    But I am a figure it out kind of guy so I wanted to do everything I could take care of it before I did that.

    Like I mentioned, the round would chamber. But even before firing, the bolt absolutely would not budge.

    So I kept the chamber empty and just charged it about 20-30 times without a round. That loosened it up quite a bit but was still a little sticky. Even after that it would eject the casing when fired but wouldn't reset the hammer. But hey, at least the bolt was not stuck like before.

    I was using 147 gr pmc bronze. So I ordered some Winchester 170 gr rounds to get a little more oomph. It would cycle great for about 3 rounds then wouldn't want to strip the next round but would reset the hammer. Fantastic I was getting somewhere.

    Got a heavier buffer. Cycles perfectly every time. Rapid fire 5-10 rounds at a time flawlessly. Also will now take PMC Bronze 147 gr without an problems.

    From what I gathered with this experience, I think it just needed broken in for the most part. Charge the bolt about 30 times. Shot it a few times with heavy grain now it works great.

    Thanks again guys for you input. It is appreciated.
     

    sig1473

    Master
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    100   0   0
    May 28, 2009
    2,759
    12
    The Greater Good
    What kind of buffer tube are you using? An AR-15 or AR-10 receiver extension? In a 308 AR when using an AR15 RE you will need a shorter 308 buffer, while using an AR10 RE you can use AR15 buffers(H3 usually).
     
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