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Thread: Wont lock back on empty magazine with overgassed upper

  1. #11
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    Quote Originally Posted by SHERWINVILLARETE View Post
    Hmm. A carbine buffer is right for well gassed guns or undergassed guns.
    No. It's too light. Some ARs thought to be over gassed are actually under buffered.

    Im no expert, but what weight buffers do the military use on their M4s?
    Military issue M4s have H2 buffers.

    First, rid yourself of the notion that ejection angle is any kind of indicator as to how your upper is gassed. The change in angle using higher pressure ammo is more an indicator your extractor spring is weak. Test the problematic upper with just the BGC from the properly gassed upper and see what ejection angle you get.

    Second, not locking back is an indicator that your gas system is leaking and is beginning to short stroke. Magpul has made several rolling changes to their mags over the years. Older mags may require the carrier to travel rearward more to lock back. (Lock back point also varies between different brands of mags.) Inspect for leaks, worn gas rings and worn gas tube.

    Third, not locking back can also indicate the mag release is improperly adjusted. The button may need to be turned in a bit.

    Fourth, how do you know your upper is over-gassed? Ejection angle isn't a reliable indicator. (If you don't believe me, get a barrel with an overly large gas port and an adjustable gas block and use ejection angle to tune it.)

    Fifth, if the buffer is a carbine weight, you're wasting your time. Replace it with an H, or better yet, H2 buffer.

    Sixth, replace the extractor spring with a Colt or Sprinco M4 spring. Trouble shooting with a weak extractor spring is a waste of time. Extractor springs are cheap.

    Seventh, check the length of the action spring. If it's too short, it needs to be replaced. If it's been used a lot, it could have collapsed.
    Last edited by MistWolf; 03-05-21 at 15:16.
    INSIDE PLAN OF BOX
    1. ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
    2. MATCH SCRATCHES ON MATCH-BOX
    3. MATCH LIGHTS FUSE TO TNT
    4. BOOM!
    5. HA-HA!!

    -WILE E. COYOTE, AUTHOR OF "EVERYTHING I NEEDED TO KNOW IN LIFE, I LEARNED FROM GOLDBERG & MURPHY"

    http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Carbine/DSC_0114.jpg
    I am American

  2. #12
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    Im gonna test with another bcg and use an H buffer.

  3. #13
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    Quote Originally Posted by markm View Post
    I think the currenty M4s come with H buffers.
    H2 buffers.
    The simple fact of the matter is this, America has never not been great.
    - Mark Robinson

  4. #14
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    Quote Originally Posted by SHERWINVILLARETE View Post
    Hmm. A carbine buffer is right for well gassed guns or undergassed guns.

    I dont think its the spring cuz the spring worked well for the longest time on multiple uppers.


    Im no expert, but what weight buffers do the military use on their M4s?
    Carbine buffers are shit. Current M4 use H2 buffers
    The simple fact of the matter is this, America has never not been great.
    - Mark Robinson

  5. #15
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    Quote Originally Posted by MistWolf View Post
    No. It's too light. Some ARs thought to be over gassed are actually under buffered.



    Military issue M4s have H2 buffers.

    First, rid yourself of the notion that ejection angle is any kind of indicator as to how your upper is gassed. The change in angle using higher pressure ammo is more an indicator your extractor spring is weak. Test the problematic upper with just the BGC from the properly gassed upper and see what ejection angle you get.

    Second, not locking back is an indicator that your gas system is leaking and is beginning to short stroke. Magpul has made several rolling changes to their mags over the years. Older mags may require the carrier to travel rearward more to lock back. (Lock back point also varies between different brands of mags.) Inspect for leaks, worn gas rings and worn gas tube.

    Third, not locking back can also indicate the mag release is improperly adjusted. The button may need to be turned in a bit.

    Fourth, how do you know your upper is over-gassed? Ejection angle isn't a reliable indicator. (If you don't believe me, get a barrel with an overly large gas port and an adjustable gas block and use ejection angle to tune it.)

    Fifth, if the buffer is a carbine weight, you're wasting your time. Replace it with an H, or better yet, H2 buffer.

    Sixth, replace the extractor spring with a Colt or Sprinco M4 spring. Trouble shooting with a weak extractor spring is a waste of time. Extractor springs are cheap.

    Seventh, check the length of the action spring. If it's too short, it needs to be replaced. If it's been used a lot, it could have collapsed.
    ^^^Listen to this guy. That pie chart is gabage I wish people would quit citing it. BTW, a carbine action spring should measure between 10 1/16" and 11 1/4", do not stretch it, cut it or any of that crap.
    The simple fact of the matter is this, America has never not been great.
    - Mark Robinson

  6. #16
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    Main reason why im running a carbine buffer is because i shoot a lot of weak ammo like steel cased through a BCM 14.5 middy which is considered super soft shooting by many.

    Thanks for yalls input. I will do some testing and try to slow the bcg down and ill get back to you guys with an update lol

  7. #17
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    Quote Originally Posted by SHERWINVILLARETE View Post
    Main reason why im running a carbine buffer is because i shoot a lot of weak ammo like steel cased through a BCM 14.5 middy which is considered super soft shooting by many.
    That's the ONLY set up I run with a lighter buffer than H2 carbine. H buffer is the sweet spot on my BCM 14.5 middies.
    "You people have too much time on your hands." - scottryan

  8. #18
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    I have an H2 buffer and Sprinco Blue spring in one of my BCM 14.5" mid-lengths, it runs great.
    The simple fact of the matter is this, America has never not been great.
    - Mark Robinson

  9. #19
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    Quote Originally Posted by MistWolf View Post
    No. It's too light. Some ARs thought to be over gassed are actually under buffered.
    Military issue M4s have H2 buffers.
    For the first ten years they ran fine with standard weight buffers.

    The official reports list reducing bolt bounce as the reason for the switch to the two tungsten weight buffer. There is no mention of excessive bolt velocity with the standard weight buffer.

  10. #20
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    Recoil is sharper with a carbine weight buffer. I experimented with an upper equipped with an adjustable gas block, suppressed and unsuppressed, with carbine, H and H2 buffers. After all the internet chatter about using different buffer weights to control over gassing, I was surprised fo find out all three buffers used the same gas setting. The difference was how recoil felt. Recoil with the carbine buffer was uncomfortably sharp. You can feel the reciprocating mass hit the end of the RE harder.
    Last edited by MistWolf; 03-08-21 at 10:35.
    INSIDE PLAN OF BOX
    1. ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
    2. MATCH SCRATCHES ON MATCH-BOX
    3. MATCH LIGHTS FUSE TO TNT
    4. BOOM!
    5. HA-HA!!

    -WILE E. COYOTE, AUTHOR OF "EVERYTHING I NEEDED TO KNOW IN LIFE, I LEARNED FROM GOLDBERG & MURPHY"

    http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Carbine/DSC_0114.jpg
    I am American

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