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Thread: Overgassing in hot weather temperatures?

  1. #41
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    Quote Originally Posted by T2C View Post
    The shortest barrels I have considerable experience with are 14.5". In your experience how many rounds would it take for a gas port to erode to .005" larger than on a new 16" barrel if shooting at a moderate pace, no magazine dumps, etc.?
    Your gas port does not erode in diameter. If you start with a 0.062" gas port after a few thousand round you still will not be slipping a 0.065" diameter gage pin in the hole.



    This quote sums it up quite well:

    "People have the mistaken idea that gas port erosion is the gas port actually getting bigger.

    "It ain't so.

    "The erosion mechanism is a widening of the gas port on the downstream side, making the gas port a more efficient nozzle, thereby allowing increasing the maximum mass flow through the port. This makes the post-port pressure higher. If you look at a typical eroded port, gauging the hole would not reveal a significant enlargement of the port."
    Last edited by lysander; 07-29-21 at 12:55.

  2. #42
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    Quote Originally Posted by lysander View Post
    Your gas port does not erode in diameter. If you start with a 0.062" gas port after a few thousand round you still will not be slipping a 0.065" diameter gage pin in the hole.



    This quote sums it up quite well:

    "People have the mistaken idea that gas port erosion is the gas port actually getting bigger.

    "It ain't so.

    "The erosion mechanism is a widening of the gas port on the downstream side, making the gas port a more efficient nozzle, thereby allowing increasing the maximum mass flow through the port. This makes the post-port pressure higher. If you look at a typical eroded port, gauging the hole would not reveal a significant enlargement of the port."
    Thank you, a picture is worth a thousand words.

  3. #43
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    The .005" example is not due to erosion, but due to different manufacturers various specifications.

    Quote Originally Posted by T2C View Post
    In your experience how many rounds would it take for a gas port to erode to .005" larger than on a new 16" barrel if shooting at a moderate pace, no magazine dumps, etc.?
    Black River Tactical
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5"
    BRT EZTUNE Preset Gas Tubes - CAR, MID
    BRT Bolt Carrier Groups M4A1, M16 CHROME

  4. #44
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    Quote Originally Posted by MistWolf View Post
    Bottom line- You can use the upgraded Colt spring which is proven to work. Or you can take your chances with the spring that made a redesigned spring necessary.
    Why does Daniel Defense still using a silver (rifle?) spring and o-ring in 2020? Longer life than the Colt carbine spring seemed like a plausible explanation for the choice, and relevant to the claim that the DD extractor setup was likely wearing out at 1500 rounds.

  5. #45
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    Quote Originally Posted by MistWolf View Post
    I prefer to recommend Colt extractor springs because I have first hand experience with them.

    I have very little hands on experience with the Sprinco spring. However, I did have a discussion on the subject with Will Larson who had extensive experience working on ARs (along with other families of weapons) in a combat zone as well as here in the US. He thought enough of the Sprinco spring that he recommended Sionics and SOLGW use them in their ARs. Will's bona fides were good enough that I recommend the Sprinco springs based on his say so. I haven't heard any complaints from anyone using the Sprinco spring.

    I see no reason to replace a Sprinco spring with a Colt spring or vice versa.

    Will passed away not long after I took his armorer's course. He is missed.
    We were likely in the same class. Anyhow straight from the M4C archives 2019 by Will himself

    [The Colt copper washed extractor spring is a good option, as is the Sprinco enhanced spring. I have also used (and still have) BCM enhanced springs as well. Any of them will work.]

    Nuff said?
    High speed floor buffer operator. For that low drag shine.

  6. #46
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    Quote Originally Posted by lysander View Post
    Your gas port does not erode in diameter. If you start with a 0.062" gas port after a few thousand round you still will not be slipping a 0.065" diameter gage pin in the hole.



    This quote sums it up quite well:

    "People have the mistaken idea that gas port erosion is the gas port actually getting bigger.

    "It ain't so.

    "The erosion mechanism is a widening of the gas port on the downstream side, making the gas port a more efficient nozzle, thereby allowing increasing the maximum mass flow through the port. This makes the post-port pressure higher. If you look at a typical eroded port, gauging the hole would not reveal a significant enlargement of the port."
    How much does the bolt speed change with a dramatic amount of erosion?
    Train 2 Win

  7. #47
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    Quote Originally Posted by Disciple View Post
    Why does Daniel Defense still using a silver (rifle?) spring and o-ring in 2020? Longer life than the Colt carbine spring seemed like a plausible explanation for the choice, and relevant to the claim that the DD extractor setup was likely wearing out at 1500 rounds.
    I have no idea. But my experience is the rifle spring, with or without O ring, isn't as durable in shorter ARs. Especially when a suppressor is added.

    We pin gas blocks, stake gas keys and castle nuts, lube carriers, grease and torque three times the barrel nut- all in the name of reliability and durability. But folks still cling to the problematic old style extractor spring.
    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

  8. #48
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    Quote Originally Posted by utahjeepr View Post
    We were likely in the same class.
    The class was at Ready Gunner. My brother was there with me. The class was well worth it.
    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

  9. #49
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    Quote Originally Posted by MistWolf View Post
    The class was at Ready Gunner. My brother was there with me. The class was well worth it.
    Yeah, I kinda remember you guys. It's a bit fuzzy. I'm old.
    High speed floor buffer operator. For that low drag shine.

  10. #50
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    Yep, it sure does. That's why people think M4s and Mk18s are overgassed. They have to be able to work whether it's 130 or -40 outside. Try taking your perfectly tuned AR out on a really cold day and firing a round straight down into the ground. One thing if it's a competition gun that you can tune for the season, quite another for a nightstand gun that has to just work no matter what.

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