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Thread: Minimizing Gas to Face

  1. #1
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    Minimizing Gas to Face

    I'm hoping to absorb some technical information from people much more educated about the AR platform than myself. Let me preface my question with the following
    1. All of my rifles are suppressor ready or have direct thread suppressors on them (with rockset)
    2. I'm already using the A5 buffer system + sprinco springs
    3. I'm using LMT enhanced carriers in most rifles
    4. Most rifles have an adjustable gas block
    5. For the above rifles, I have a 16" Mid length BA Barrel, a 14.5" Mid Length BCM ELW Barrel, and a 11.5" Carbine Length Sionics Reduced Gas port barrel


    Given the above, I still get a decent amount of gas to the face compared to unsuppressed guns, albeit minimized by taking the above steps.

    For the following, please correct any misinformation/assumptions that I'm about to list; I'm just trying to learn here. Anyway, I was thinking about gas port placement/size + guns that are permanently suppressed. From my understanding about gas hitting your face, it is a combination of excess gas coming from the gas tube, as well as back-pressure coming from the chamber. Adjustable gas blocks help with the former, but do less to help the latter. This seems to be because the suppressor is keeping chamber pressure higher, longer, but not high enough to cause extraction/ejection malfunctions.

    Questions
    • Given one has a permanently attached suppressor, wouldn't it make sense to shorten the length between the gas port and the end of the barrel? E.g. a 12.5" or 13.5" mid length barrel would delay the bolt/bolt carrier unlock further compared to say a 12.5" or 13.5" carbine barrel?
    • If a 12.5" mid length barrel was on the edge of being under gassed due to lack of dwell time, wouldn't adding a suppressor help?
    • Am I wrong to think that if you add a suppressor to a perfectly functioning gun, you've increased dwell time and its likely no longer perfectly functioning (albeit, probably still functions fine)?
    • If the above are true, why doesn't anyone offer these types of barrels? The closest thing I've ever seen is maybe the Faxxon 11.5" mid-length barrel. It seems the only other way you'd get this type of barrel is to cut a 16" barrel down.
    • Isn't the A5 system and heavier buffers sort of accomplishing the same thing by delaying bolt/carrier unlock thus working to reduce back pressure to your face?

    What I'm kinda getting at is that it seems a shorter distance between the gas port and the end of your barrel would allow chamber pressure to drop further than a longer length system and thus reduce gas to your face. E.g. a 11.5" pistol length barrel would in theory spew more back pressure gas in your face compared to an 11.5" mid-length barrel assuming they are both functioning reliable/both have adjustable gas blocks. Thoughts?
    Last edited by abso; 08-20-20 at 18:24.

  2. #2
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    Answers:
    Yes, it does.
    Yes, it would.
    No, you're not.
    We do https://blackrivertactical.com/WP/BR...rel-p144898916
    No, adding mass does not delay the start of the cycle like moving the gas port further down.

    Quote Originally Posted by abso View Post
    I'm hoping to absorb some technical information from people much more educated about the AR platform than myself. Let me preface my question with the following
    1. All of my rifles are suppressor ready or have direct thread suppressors on them (with rockset)
    2. I'm already using the A5 buffer system + sprinco springs
    3. I'm using LMT enhanced carriers in most rifles
    4. Most rifles have an adjustable gas block
    5. For the above rifles, I have a 16" Mid length BA Barrel, a 14.5" Mid Length BCM ELW Barrel, and a 11.5" Carbine Length Sionics Reduced Gas port barrel


    Given the above, I still get a decent amount of gas to the face compared to unsuppressed guns, albeit minimized by taking the above steps.

    For the following, please correct any misinformation/assumptions that I'm about to list; I'm just trying to learn here. Anyway, I was thinking about gas port placement/size + guns that are permanently suppressed. From my understanding about gas hitting your face, it is a combination of excess gas coming from the gas tube, as well as back-pressure coming from the chamber. Adjustable gas blocks help with the former, but do less to help the latter. This seems to be because the suppressor is keeping chamber pressure higher, longer, but not high enough to cause extraction/ejection malfunctions.

    Questions
    • Given one has a permanently attached suppressor, wouldn't it make sense to shorten the length between the gas port and the end of the barrel? E.g. a 12.5" or 13.5" mid length barrel would delay the bolt/bolt carrier unlock further compared to say a 12.5" or 13.5" carbine barrel?
    • If a 12.5" mid length barrel was on the edge of being under gassed due to lack of dwell time, wouldn't adding a suppressor help?
    • Am I wrong to think that if you add a suppressor to a perfectly functioning gun, you've increased dwell time and its likely no longer perfectly functioning (albeit, probably still functions fine)?
    • If the above are true, why doesn't anyone offer these types of barrels? The closest thing I've ever seen is maybe the Faxxon 11.5" mid-length barrel. It seems the only other way you'd get this type of barrel is to cut a 16" barrel down.
    • Isn't the A5 system and heavier buffers sort of accomplishing the same thing by delaying bolt/carrier unlock thus working to reduce back pressure to your face?

    What I'm kinda getting at is that it seems a shorter distance between the gas port and the end of your barrel would allow chamber pressure to drop further than a longer length system and thus reduce gas to your face. E.g. a 11.5" pistol length barrel would in theory spew more back pressure gas in your face compared to an 11.5" mid-length barrel assuming they are both functioning reliable/both have adjustable gas blocks. Thoughts?
    Black River Tactical
    BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
    BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
    BRT Bolt Carrier Groups M4A1, M16 CHROME
    BRT Covert Comps 5.56, 6X, 7.62

  3. #3
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    ETA: You weren't alking about having problems with functioning, rather gas to face.

    Skimmed it, but didn't see you mention charging handle. Here's a link to something you could try:

    http://www.03designgroup.com/technot...harging-handle

    Folks have talked about replacing the EA with a gas vent:

    https://www.weaponoutfitters.com/ar-gas-vent.html

    Here's a thread:

    http://www.silencertalk.com/forum/vi...vfxrHLoiNgkXnA
    Last edited by 26 Inf; 08-20-20 at 18:46.
    Patriotism means to stand by the country. It does not mean to stand by the President... - Theodore Roosevelt, Lincoln and Free Speech, Metropolitan Magazine, Volume 47, Number 6, May 1918.

    Every Communist must grasp the truth. Political power grows out of the barrel of a gun. Our principle is that the Party commands the gun, and the gun must never be allowed to command the Party Mao Zedong, 6 November, 1938 - speech to the Communist Patry of China's sixth Central Committee

  4. #4
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    The cans themselves matter too, what are you using?
    Sic semper tyrannis.

  5. #5
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    I gotta get my mind out of the gutter. I'll just leave it at that.

  6. #6
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    Since I started running the newest generation of BCM Gunfighter CH and lubricant with a thicker viscosity than CLP (like Wilson Combat Ultima Lube), I have had little gas or lube to the face (DD Mk18 and Colt 6933 using 556 Saker, Sandman S, Sandman K).

  7. #7
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    PRI Gas Buster charging handle helps. Specific can matters a lot. Triarc makes a 12.5” mid length that I’ve been eyeballing for my Turbo K.
    RLTW

    Former Action Guy
    Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.

  8. #8
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    Quote Originally Posted by militarymoron View Post
    I gotta get my mind out of the gutter. I'll just leave it at that.


    I hate suppressors on ARs. I literally have a 5.56 can just sitting in the safe doing nothing. If I could afford the Glass, I'd build a Rem 700 for it.
    "What would a $2,000 Geissele Super Duty do that a $500 PSA door buster on Black Friday couldn't do?" - Stopsign32v

  9. #9
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    Quote Originally Posted by Clint View Post
    Answers:
    Yes, it does.
    Yes, it would.
    No, you're not.
    We do https://blackrivertactical.com/WP/BR...rel-p144898916
    No, adding mass does not delay the start of the cycle like moving the gas port further down.
    Thanks Clint - I just saw that there is a massive thread regarding your barrels right below my thread. I'll check it out - thanks a bunch
    Do you mind giving cliff notes as to why the A5 system doesn't delay the unlock? Is it that it just slows down carrier speed, but the unlock time is more or less the same?

    Quote Originally Posted by 26 Inf View Post
    ETA: You weren't alking about having problems with functioning, rather gas to face.

    Skimmed it, but didn't see you mention charging handle. Here's a link to something you could try:

    http://www.03designgroup.com/technot...harging-handle

    Folks have talked about replacing the EA with a gas vent:

    https://www.weaponoutfitters.com/ar-gas-vent.html

    Here's a thread:

    http://www.silencertalk.com/forum/vi...vfxrHLoiNgkXnA
    I've been using Raptor charging handles in whatever flavor of the month brand that is currently producing them. I can't even remember the various ones at this point but they seem all identical.

    Quote Originally Posted by Wake27 View Post
    The cans themselves matter too, what are you using?
    They are a bit stranger than most, but I've been using my TB Ultra 7 on the 16", a YHM titanium 5.56/ultra 30 can on the 14.5", then the most esoteric one, a Liberty Triumph on the 11.5". My general observations are that the Ultra 7/16" barrel has the least blowback, the 14.5" with the 30 cal can has the second least, followed by the 5.56 can on the 14.5" and the 11.5" being the worst. The annoying thing is that between the two YHM suppressors, there is seemingly little noise reduction difference but a significant amount of blowback difference - probably just due to the 30cal can being bigger. If you're wondering why I run a TB Ultra 7 on an AR15, its because that rifle doesn't see fast/high round counts and I don't really have a use for it after I went to 6.5CM for my precision rifles; I bought a TB Ultra 6.5 because I hate money.

    Quote Originally Posted by militarymoron View Post
    I gotta get my mind out of the gutter. I'll just leave it at that.
    hehe

    Quote Originally Posted by LowSpeed_HighDrag View Post
    Since I started running the newest generation of BCM Gunfighter CH and lubricant with a thicker viscosity than CLP (like Wilson Combat Ultima Lube), I have had little gas or lube to the face (DD Mk18 and Colt 6933 using 556 Saker, Sandman S, Sandman K).
    Yeah - as above, I've been using raptor charging handles. For lube I just always use slip 2000; I still have about a quarter of a big bottle left which I'd use up prior to looking to change things up.

    Quote Originally Posted by 1168 View Post
    PRI Gas Buster charging handle helps. Specific can matters a lot. Triarc makes a 12.5” mid length that I’ve been eyeballing for my Turbo K.
    Yeah

    Quote Originally Posted by markm View Post


    I hate suppressors on ARs. I literally have a 5.56 can just sitting in the safe doing nothing. If I could afford the Glass, I'd build a Rem 700 for it.
    I don't blame you, though even wearing my sordins for ear protection, I still get a bit of concussive feedback when shooting indoors. I'd rather take the slightly uncomfortable eyes/face than lose more hearing over time.

    Thanks all!
    Last edited by abso; 08-21-20 at 12:42.

  10. #10
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    Quote Originally Posted by 26 Inf View Post
    ETA: You weren't alking about having problems with functioning, rather gas to face.

    Skimmed it, but didn't see you mention charging handle. Here's a link to something you could try:

    http://www.03designgroup.com/technot...harging-handle

    Folks have talked about replacing the EA with a gas vent:

    https://www.weaponoutfitters.com/ar-gas-vent.html

    Here's a thread:

    http://www.silencertalk.com/forum/vi...vfxrHLoiNgkXnA
    Never thought about venting through the forward assist. Would drilling a hole in my existing FA accomplish the same thing as the one above?


    Sent from my iPhone using Tapatalk

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