Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 27

Thread: Extreme Cold Gas System Operation

  1. #11
    Join Date
    Jun 2008
    Location
    TN
    Posts
    1,384
    Feedback Score
    0
    What configurations do you think would pass the extremely cold test provided that they are a quality rifle and using standard 5.56 ammo ie M193 or M855.

    I would venture the following four would definitely pass the test.

    20" rifle
    16" Midlength
    16" carbine
    14.5" carbine

    What other should be added to the list?

  2. #12
    Join Date
    Oct 2011
    Location
    Alaska
    Posts
    3,523
    Feedback Score
    3 (100%)
    Do other configurations like the 16" midlength pass this test easily?
    Clint, in real world testing at temps as low as -28F and cold sinks over over 24 hours, I have yet to have either my DD 16" middy or my BCM 16" middy fail in any way. It's not exactly high round count at those temps, but I haven't had an issue. This is with crappy .223 also, 5.56 would only perform better.

  3. #13
    Join Date
    Nov 2010
    Location
    Georgetown Texas
    Posts
    153
    Feedback Score
    1 (100%)
    I've run my bcm middy in 100deg Texas heat at hogs and paper as well temps down to -40 deg above the arctic circle with the same h2 buffer and spring with absolutely no issues albeit a little sluggish.

  4. #14
    Join Date
    Oct 2010
    Posts
    962
    Feedback Score
    21 (100%)
    I think all of those would pass too. I'd imagine 11.5 and 12.5 carbine would also work fine.

    Quote Originally Posted by crusader377 View Post
    What configurations do you think would pass the extremely cold test provided that they are a quality rifle and using standard 5.56 ammo ie M193 or M855.

    I would venture the following four would definitely pass the test.

    20" rifle
    16" Midlength
    16" carbine
    14.5" carbine

    What other should be added to the list?
    B.A.S. Mechanical Engineering Technology

  5. #15
    Join Date
    Jun 2006
    Location
    12S VA 868 817 (NAD83)
    Posts
    1,500
    Feedback Score
    0
    Quote Originally Posted by crusader377 View Post
    What configurations do you think would pass the extremely cold test provided that they are a quality rifle and using standard 5.56 ammo ie M193 or M855.

    I would venture the following four would definitely pass the test.

    20" rifle
    16" Midlength
    16" carbine
    14.5" carbine

    What other should be added to the list?
    As Eric D said, the 12.5 Carbine is for sure on the list... don't get too wound up about this, seriously; I do the testing on combinations as sort of a final acid test and there are variables between any two identical guns - even at that, most guns that are single shots, are only that way for one or two rounds...

    Again, it is just a test I like to use to cull out systems that are "raged edge" of functioning... and as many people have pointed out the systems that are known to be reliable (standard rifle, 16" middy, M4 config, etc) are proven to work in even the most extreme spread of environments.
    Please let me know if I have offended you...
    I would like to move on to my next task.


    I provide legal consultation and training - specializing in the Law of Gravity.

  6. #16
    Join Date
    Oct 2012
    Posts
    980
    Feedback Score
    1 (100%)
    The ammo being cold will be a much larger factor IMO than the rifle. Many powders are highly temp dependent.

  7. #17
    Join Date
    Aug 2010
    Location
    North Florida
    Posts
    2,679
    Feedback Score
    1 (100%)
    The Army and Marines have units trained to fight in arctic conditions, presumably they use standard weapons, M4s, M16s, everything else in those cold conditions. Isn't that right?

  8. #18
    Join Date
    Oct 2006
    Location
    College Station, Texas
    Posts
    1,539
    Feedback Score
    6 (100%)
    There's a general MILSPEC for all US military small arms and ammunition -- these are specifically for 5.56:

    MIL-C-9963F
    CARTRIDGE, 5.56MM, BALL M193


    3.6 Velocity. The average velocity of the sample cartridges, conditioned at 70 + 2 Fahrenheit (F), shall be 3165 feet per second (ft/sec) plus or minus 40 ft/sec, at 78 feet from the muzzle of the weapon. The standard deviation of the velocities shall not exceed 40 ft/sec,

    3.7 Chamber pressure.

    3.7.1 Measurement by copper-crush cylinder. The average chamber pressure
    o€ the sample cartridges, conditioned at 70 +/- 2F, shall not exceed 52,000 pounds per square inch (PSI). The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 58,000 PSI.

    3.7.2 Measurement by piezoelectric transducer. The average chamber pressure of the sample cartridges, conditioned at 70 + 2F, shall not exceed 55,000 PSI. The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 61,000 PSI.

    3.8 Port pressure.

    3.8.1 Measurement by copper crush cylinder. The average port pressure of the sample cartridges, conditioned at 70 +/- 2F, shall be 15,000 PSI +/- 2000 PSI.

    3.8.2 Measurement by piezoelectric transducer. The average port pressure of the sample cartridges, conditioned at 70 +/- 2F shall be shall be 14,400 PSI +/- 2000 PSI.

    3.9 Temperature stability. When the sample cartridges are subjected to the following storage conditions, the average velocity shall not decrease by more than 250 ft/sec and the average chamber pressure by either method used in 3.7 shall not increase by more than 5000 PSI, the average port pressure by either method used in 3.8 shall neither increase nor decrease by more than 2000 PSI with respect to the average velocity, chamber pressure and port pressure of the sample cartridges of the same lot, conditioned at 70 +/- 2 F for a minimum of twenty minutes. Any increases in velocity and decreases in chamber pressure of the sample cartridges under these temperature conditions are acceptable,

    Stored at 125 +/- 2F for not less than one hour and fired at that temperature.
    Stored at -65 +/- 5F for not less than one hour and fired at that temperature.


    ––––––––––––––––––––––––––––––––––––––

    MIL-C-63989C
    CARTRIDGE, 5.56MM, BALL, M855


    3.6 Velocity. The average velocity of the cartridges,
    conditioned at 70 +/- 2F, shall be 3000 feet per second (fps) plus or minus 40 fps at 78 feet from the
    muzzle of the weapon. The standard deviation of the velocities shall not exceed 40 fps.

    3.7 Chamber pressure. The average chamber pressure of the sample cartridges, conditioned at 70 +/- 2F shall not exceed 55,000 psi. Neither the chamber pressure of an individual sample test cartridge nor the average chamber pressure plus three standard deviations of chamber pressure shall exceed 61,000 psi.

    3.8 Port Pressure. The mean port pressure minus three
    standard deviations shall not be less than 12,700 psi for sample cartridge conditioned to 70 +/- 2F.

    3.10 Temperature stability. The action time, pressure and velocity of sample cartridges conditioned and fired at the temperature extremes specified below shall be in accordance with 3.10.1, 3.10.2, 3.10.3, and 3.10.4

    a. Conditioned at 125 +/- 2F for not less than one hour and fired at that temperature.
    b. Conditioned at -65 +/- 2F for not less than one hour and fired at that temperature.

  9. #19
    Join Date
    Nov 2010
    Location
    MI
    Posts
    3,055
    Feedback Score
    21 (100%)
    Quote Originally Posted by sinister View Post
    There's a general MILSPEC for all US military small arms and ammunition -- these are specifically for 5.56:
    -2000 psi port pressure or about 85% of normal
    No spec for chamber pressure loss.

    It looks like ammo "power" can be expected to be down by at least 10% in cold environments.

    Quote Originally Posted by K.L. Davis View Post
    even at that, most guns that are single shots, are only that way for one or two rounds...

    and as many people have pointed out the systems that are known to be reliable (standard rifle, 16" middy, M4 config, etc) are proven to work in even the most extreme spread of environments.
    The fact that even suspect configurations warm up after a few rounds points to either chambers warming up, restoring ammo power or cold gas system components warming up and no longer "robbing" energy from the gas.

    This all circles back around to the concept of the low dwell time configurations being less robust / more sensitive to variations in ammo or environmental conditions.

    As to WHY short dwell configurations are less robust:

    I'm not 100 sure at this point.
    Last edited by Clint; 09-20-13 at 07:34.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  10. #20
    Join Date
    Dec 2007
    Location
    Alaska
    Posts
    7,905
    Feedback Score
    9 (100%)
    Use thinner lube. A friend of mine working in temps as low as -50 uses 0 weight motor oil and it works great. Also avoid having the gun go inside and outside in these conditions. Condensation turns to ice and can stop the guns cold.
    Pat
    Serving as a LEO since 1999.
    USPSA# A56876 A Class
    Firearms Instructor
    Armorer for AR15, 1911, Glocks and Remington 870 shotguns.

Page 2 of 3 FirstFirst 123 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •