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Thread: Blown primers and other malfunction troubleshooting

  1. #41
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    If you were running too hot I would expect the primers to be more flattened before you started seeing the cratering around the firing pin.

    That and bolt flow marks on the case head.

    I know you guys do a ton of reloading and would be able to tell, are any of the cases with primer failure showing loose pockets when you reload them?

    I'm still shooting some IMI/Lapua 762x39 fire formed to grendel. The limits of case life are the large rifle primers pockets getting too large. I haven't had primers fall out, but I can tell when I prime with a Lee Auto prime that the tension is very low.

  2. #42
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    Quote Originally Posted by pinzgauer View Post
    If you were running too hot I would expect the primers to be more flattened before you started seeing the cratering around the firing pin.

    That and bolt flow marks on the case head.

    I know you guys do a ton of reloading and would be able to tell, are any of the cases with primer failure showing loose pockets when you reload them?

    I'm still shooting some IMI/Lapua 762x39 fire formed to grendel. The limits of case life are the large rifle primers pockets getting too large. I haven't had primers fall out, but I can tell when I prime with a Lee Auto prime that the tension is very low.
    Do you use the cases with low tension? I have noticed some 5.56/.223 cases with that problem and I just discard them. If I had to buy cases and fire form them I may not be so cavalier about it.

    Andy

  3. #43
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    Quote Originally Posted by AndyLate View Post
    Do you use the cases with low tension? I have noticed some 5.56/.223 cases with that problem and I just discard them. If I had to buy cases and fire form them I may not be so cavalier about it.

    Andy
    When I feel one with low tension while priming I put a sharpie X on the head. Go ahead and plink with it, then retire it.

    I have several hundred lapua grendel cases, I just started with IMI 7.62x39 fireformed in 2007-2008 when brass was unobtanium. Some of those are still hanging in there. Primer pocket tension is the life limit, only had a couple of neck splits.

  4. #44
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    Quote Originally Posted by pinzgauer View Post
    When I feel one with low tension while priming I put a sharpie X on the head. Go ahead and plink with it, then retire it.

    I have several hundred lapua grendel cases, I just started with IMI 7.62x39 fireformed in 2007-2008 when brass was unobtanium. Some of those are still hanging in there. Primer pocket tension is the life limit, only had a couple of neck splits.
    Mark does the same thing, he draws two circles around the brass and we blast away and he trashes it.

    PB
    "Air Force / Policeman / Fireman / Man of God / Friend of mine / R.I.P. Steve Lamy"

  5. #45
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    Blown primers and other malfunction troubleshooting

    So finally got some Forster headspace gages in and confirmed that was not the issue. I was kind of hoping that it would be so I could move on. Still need to get it out and try it with an E-carrier. I may just replace the whole REBCG with an EBCG and hope that does the trick. I’ve played with my can on my 10.5s the most, both of which have EBCGs and like that setup a lot.


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    Last edited by Wake27; 02-26-23 at 19:54.
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  6. #46
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    Quote Originally Posted by markm View Post
    The funny thing is with a Rem 700 factory bolt, I get primer flow with 308 sub sonics. Their firing pin holes are a little large.
    Another thing is if your firing pin spring is weak it can do this too

  7. #47
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    LMT E-BCG on the way. The Geissele passed head space so I don't know that it'll make a difference but its worth a shot. I also cleaned it and dropped the buffer weight down. Too many variables to know what did it if it works but I'm hoping to use the upper in an LPVO course at the end of the month so I just need it to run.
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  8. #48
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    Blown primers and other malfunction troubleshooting

    Alright so I have to check my round count since throwing the E-BCG in and dropping the buffer but so far, no malfunctions due to blown primers. Last weekend, I was using the A5H1 (per Criterion CS) and today I went back to the A5H3.

    But.

    The BCG is having frequent trouble feeding the first round from USGI mags when I hit the bolt release. I believe I’ve had four of these failures between the last two weeks and I didn’t take note of it at the time, but I believe this was with two different lowers. PMAGs have been a non-issue and I’ve had a few USGI mags that were fine, but every stoppage was with GI mags and none of them were the same mag. The round would just start to feed, so I had to rack it every time.

    Also, I noticed a primer that was almost dislodged when picking up brass today. I kept most of the other brass but still need to sort through and see if there are others. No way of knowing if this was the same gun or not since I had several out today, but I’m guessing that it is.




    And, as I’m shooting faster, I’m noticing more recoil than I’d expect based on my other guns. I don’t have any other 12.5s but between my 11.5 Geissele and several 14.5s (most with the same flash hider and A5 buffer), this thing kicks a bit. I’ve also noticed that it does spit gas in my face more than I’d expect with the KAC QDC, even with the E-BCG.

    Finally, rounds have some zip. I chrono’d it today with the same 56gr MEN at an average of 3099.4 FPS and 77gr S&B at 2633 FPS. For reference, my 14.5 Mod2 KAC was at 2984.8 and 2585.4. All five round groups, taken one after another. Between the recoil and gas to face, I’m only a little surprised that it’s pushing rounds with more FPS than a 14.5 barrel.

    Super curious on continued thoughts here. Maybe the chamber is just a tad undersized?

    ETA - round count was 541 w/ REBCG and is 886 now so 345 rounds with the E-BCG and no fully blown primers.

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    Last edited by Wake27; 03-25-23 at 20:32.
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  9. #49
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    Perhaps I recall incorrectly, but I thought the thing to do is use a heavier buffer when switching to the E-carrier. The E-carrier can be interesting in itself. I have a semi-auto cut E-carrier on the shelf that makes whatever I put it in feel like it has excessive recoil. I also have a normal E-carrier that makes the specific upper it's in feel exceptionally smooth, particularly when used in conjunction with a Tubb flatwire spring.

  10. #50
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    Quote Originally Posted by opngrnd View Post
    Perhaps I recall incorrectly, but I thought the thing to do is use a heavier buffer when switching to the E-carrier. The E-carrier can be interesting in itself. I have a semi-auto cut E-carrier on the shelf that makes whatever I put it in feel like it has excessive recoil. I also have a normal E-carrier that makes the specific upper it's in feel exceptionally smooth, particularly when used in conjunction with a Tubb flatwire spring.
    Criterion CS wanted me to drop to an A5H1 from the H3 but that was without adding the E-BCG. It was super snappy with that so I went back to the H3. I have two other uppers with E-BCGs, a DD 10.3 and Triarc 105. The Triarc is fine but the DD has always felt buttery smooth.
    Sic semper tyrannis.

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