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Thread: Bolt fails to stay open on PMAG M3 but ok with Lancer L5 AWM mag

  1. #11
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    Quote Originally Posted by JusticeM4 View Post
    +1

    I had same overgassed issue on an upper I used to own. It would inconsistently not lock back on Pmags.
    I am already using a Spikes Buffer ST-T2 (4.1oz) and Sprinco blue buffer spring.
    Using the Rainer Arms 16" mid-gas system. brass ejection is 4:00 oclock and the PMAG lock back.

    Next weekend, I am going to swap the BCG(young manufacturing to the WMD Nickel-Boron) and see if that has any effect. It shouldn't . Both barrels are using the same Geissele super gas block.

    I hate to buy and try the H2/H3 buffer. Is it really worth it?

    By the way, the ejected brass looks perfect. No unusual marks on the brass.

  2. #12
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    The BCG isn't the problem here. I would pull that gas block and measure the gas port. I would also take the Spike's buffer and throw it away or sell it.

    Quote Originally Posted by patrick0525 View Post
    I am already using a Spikes Buffer ST-T2 (4.1oz) and Sprinco blue buffer spring.
    Using the Rainer Arms 16" mid-gas system. brass ejection is 4:00 oclock and the PMAG lock back.

    Next weekend, I am going to swap the BCG(young manufacturing to the WMD Nickel-Boron) and see if that has any effect. It shouldn't . Both barrels are using the same Geissele super gas block.

    I hate to buy and try the H2/H3 buffer. Is it really worth it?

    By the way, the ejected brass looks perfect. No unusual marks on the brass.



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  3. #13
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    Quote Originally Posted by patrick0525 View Post
    I am already using a Spikes Buffer ST-T2 (4.1oz) and Sprinco blue buffer spring.
    Using the Rainer Arms 16" mid-gas system. brass ejection is 4:00 oclock and the PMAG lock back.

    Next weekend, I am going to swap the BCG(young manufacturing to the WMD Nickel-Boron) and see if that has any effect. It shouldn't . Both barrels are using the same Geissele super gas block.

    I hate to buy and try the H2/H3 buffer. Is it really worth it?

    By the way, the ejected brass looks perfect. No unusual marks on the brass.
    Even though it sounds overgased, I'm just not convinced it is yet. Of course being "overgased" is really just a word and relative to other things with a gun . . .

    I think you may have a mag follower/spring issue. Maybe the follower is binding slightly on the way up for the last round and/or the spring is weak or something like that. Even if your PMAG does not have any defects, using any gen 3 PMAG could be an issue with your gun as montrala discussed above. I don't use PMAGs, so I can't be more helpful/specific on this issue.

    I may have missed it, but have you used more than one PMAG? It sounds like you haven't. I would try another (same generation) just in case. That should be cheap and easy to do. You might just have a bad PMAG.

    As you and Iraqgunz mentioned, the bolt carrier swap should have no effect.

    By the way, I never pay too much attention to ejection patterns. But that's just me.

    Joe Mamma
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  4. #14
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    This gun really needs a complete shitcanning to be honest with you.

    You have way too many aftermarket "do dads" that are not designed to work together, and some of which are consumer grade junk.

    You need a regular GI upper and lower with an high quality USGI lower parts kit.

    The buffer system needs to be completely taken back to USGI specs with a USGI buffer tube, spring and H buffer.

    You do not need an adjustable gas block. Get a factory quality barrel such as a BCM, DD, or Noveske that has a factory pinned low pro gas block.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

  5. #15
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    Quote Originally Posted by Joe Mamma View Post
    Even though it sounds overgased, I'm just not convinced it is yet. Of course being "overgased" is really just a word and relative to other things with a gun . . .

    I think you may have a mag follower/spring issue. Maybe the follower is binding slightly on the way up for the last round and/or the spring is weak or something like that. Even if your PMAG does not have any defects, using any gen 3 PMAG could be an issue with your gun as montrala discussed above. I don't use PMAGs, so I can't be more helpful/specific on this issue.

    I may have missed it, but have you used more than one PMAG? It sounds like you haven't. I would try another (same generation) just in case. That should be cheap and easy to do. You might just have a bad PMAG.

    As you and Iraqgunz mentioned, the bolt carrier swap should have no effect.

    By the way, I never pay too much attention to ejection patterns. But that's just me.

    Joe Mamma
    Next time, I will try a different PMAG M3 and maybe also a PMAG M2. The lilja barrel drawing specification PDF file says the gas port is 0.080 ". I agree gen3 PMAG is a problem with the lilja barrel upper but not with the Rainer Arms16" mid-gas length upper. In my situation the lower is same unit.

  6. #16
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    Quote Originally Posted by patrick0525 View Post
    The lilja barrel drawing specification PDF file says the gas port is 0.080 ".
    That's big.

    Just for comparison, the Colt port for their 14.5" and 16" barrels (carbine length gas system) is said to be 0.063".

    I'm curious, if you have the drawing in front of you, how thick is the barrel at the gas port on your barrel?

    Joe Mamma
    "Reliability above all else"
    NRA Certified Pistol and Rifle Instructor, Life Member
    Glock Certified Armorer
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  7. #17
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    Quote Originally Posted by Joe Mamma View Post
    That's big.

    Just for comparison, the Colt port for their 14.5" and 16" barrels (carbine length gas system) is said to be 0.063".

    I'm curious, if you have the drawing in front of you, how thick is the barrel at the gas port on your barrel?

    Joe Mamma
    I am not sure what you asking. But the barrel link is the following: http://www.riflebarrels.com/products...es/M4_navy.PDF

  8. #18
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    That is way overgassed. To put it into perspective and 11.5" SBR is around .076-.078 when done correctly. A Colt carbine is as was mentioned in the .063 range.

    Quote Originally Posted by patrick0525 View Post
    Next time, I will try a different PMAG M3 and maybe also a PMAG M2. The lilja barrel drawing specification PDF file says the gas port is 0.080 ". I agree gen3 PMAG is a problem with the lilja barrel upper but not with the Rainer Arms16" mid-gas length upper. In my situation the lower is same unit.



    Owner/Instructor at Semper Paratus Arms

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  9. #19
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    Quote Originally Posted by Iraqgunz View Post
    That is way overgassed. To put it into perspective and 11.5" SBR is around .076-.078 when done correctly. A Colt carbine is as was mentioned in the .063 range.
    Tomorrow, I will call Lilja and investigate.

  10. #20
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    The gas port size is clearly marked on the drawing. Not much to investigate unless it isn't accurate. I also wouldn't expect them to know or tell you that the TDP specifies a particular port size. I also don't expect them to tell you "yeah it's pretty large, we do that so people can shoot any type of garbage on the market". Of course, I may be completely wrong about that.

    Quote Originally Posted by patrick0525 View Post
    Tomorrow, I will call Lilja and investigate.



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