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Why proper M2 .50 cal headspace is critical

Discussion in 'General Gun Discussions' started by Slater, Apr 27, 2005.

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  1. Slater

    Slater Member

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  2. Dave R

    Dave R Member

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    Haven't seen it before. Not for the bandwidth-challenged.

    Something I don't understand. It looks like 2 shots are fired, and then the kaboom occurs, without the action cycling again. Did it cycle and then fire prematurely? Otherwise, I don't see how it happened.
     
  3. Chipperman

    Chipperman Member

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    I agree. There's a long pause after the second cycling.
    The movie is running very slowly though, so it's hard to get a good idea of timing.

    I think anyone near that would not be a happy camper though. :eek:
     
  4. Texian Pistolero

    Texian Pistolero member

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    Not sure, been thirty years since I headspaced a Ma Duece.

    Two much headspace, and you have an unsupported case, hence fractured fairy tale.
     
  5. Chupacabra

    Chupacabra Member

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  6. beemerb

    beemerb Member

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    I think I still remember that the M2 has to cocked twice to get the first round in the barrel.
     
  7. HSMITH

    HSMITH Member

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    It didn't fire twice, it takes two strokes of the charging handle to chamber a round and that is what you are seeing.

    I've seen this happen in person once, carnage but the guy lived minus one testicle and LOTS of scars.

    It usually is the result of someone over confident not using the guages, or by someone tweaking it for a little more rounds per minute and getting caught. Set them up loose and they shoot faster, set them tight and they are a little slower but there are limits.
     
  8. Texian Pistolero

    Texian Pistolero member

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    Actually...the drill is...VERY SIMPLE....

    but you DO.....have to DO...... it RIGHT.

    otherwise..there..is..a..disturbance...in...the..force.
     
  9. bogie

    bogie Member

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    I'm guessing they expected failure to occur... Did they SAY that it was excessive headspace? I'd almost think a plugged barrel or a hot round.
     
  10. jdberger

    jdberger Member

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    That's why you are supposed to fire that pig from INSIDE the tank! :D
     
  11. PMDW

    PMDW Member

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    Ahaha.

    sux2bhim
     
  12. Warbow

    Warbow Member

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    Holy crap. :eek:
     
  13. foghornl

    foghornl Member

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    Over-charged round?
    Squib round for shot 1?
    Round charged with c-4 sted of normal powder?
     
  14. cracked butt

    cracked butt Member

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    Other than the huge amount of hot gas given off, the gun looks like it held up pretty well, at least to my novice eyes. Mr. Browning designed good stuff. The guy standing next to or behind the gun might not hold up so well though.
     
  15. HankB

    HankB Member

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    Interesting - but I wonder if there's any significance to the date that's shown at the beginning?
     
  16. Kharn

    Kharn Member

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    Troops in Iraq are destroying several M2's per week due to improper headspacing (you have to headspace the M2 every time you get ready to use it). The video is meant as a training film to show the troops why following the TM to the letter is very important, forgetting one step (I think its pulling back the charging handle) will cause excessive headspace as in the video. It was taped at Rock Island Arsenal by the US Army. All of the above I discovered while reading the thread about the video at ar15.com in general discussion, but I cant find the thread again (even searched for all sorts of words I thought were in the title).

    Kharn
     
  17. HSMITH

    HSMITH Member

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    There is just short of two ounces of jacketed bullet and about 240 grains of powder in every 50 BMG round. That is not a live round on a squib, or C4 or anything like that. The power of the 50 is hard to believe if you haven't been around them, figure about 12,500 lb/ft of energy for a standard ball round!!!!!! Compare that to 350 for a 45 acp or 2600 for a 308, BIG difference.

    A blown case from excess headspace in the M2 is basically a casehead separation, so all of the hot gasses and metal being blown out come out in all directions after the extractor gets cut/blown off. The bottom is open and that is where the really dangerous parts and pieces are blown out, if you are standing behind it shooting it you are in trouble.

    Most barrels want to be 5-9 clicks out from threaded all the way in, and you can just spin them in and back them out say 7 and be fine on a gun you know with barrels you know. BUT, if there is a little piece of crud on the threads or something and the barrel stops 10 clicks short of true bottom, then you come out 7 you had BETTER be using the gauge or you WILL blow it up. It only takes two seconds to check the headspace.
     
  18. db_tanker

    db_tanker Member

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    We had the gauges right on the side of the main control panel where the TC sits in a little crown royal bag. :)

    D
     
  19. Owen

    Owen Moderator Emeritus

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    Looks alot like the engineering range at FN Herstal. The charging handle gonculator is typical Herstal.
     
  20. Kharn

    Kharn Member

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    I never knew there was a technical term for "remote-controlled charging handle puller thingie". :eek:

    Kharn
     
  21. Sergeant Sabre

    Sergeant Sabre Member

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    There is NO shot #1. What you are seeing is the device pulling the bolt back, locking it, and then releasing it. The "Clank" you hear is the bolt slamming home. First on an empty chamber, then on a loaded one. When you insert ammunition into the feed tray of an M2, it takes TWO pulls if the charging handle to chamber a round. That's what's happening here.
     
  22. Joejojoba111

    Joejojoba111 Member

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    "All, Please take a moment to look at this short video clip and feel free
    to use it for training, etc...it was put together by one of our Senior TACOM
    Small Arms Equipment Specialists at Rock Island who operated our Small Arms
    > Support Center(SASC)in Balad, Iraq; essentially a "mini Depot" repair
    > facility for all Small Arms...his comments are below.
    >
    >XXXXX
    > USAMC LAO Ft Riley
    >
    > This was done at the XXXXX here at Rock Island to re-create the
    mistakes that continue to occur in Iraq. The troops screw the barrel into
    the
    50 without pulling the bolt back to release the locking spring. They
    then loosen the barrel up 3 to 4 clicks and attempt to fire it.
    > I would see between 5 to 8 of these guns a week at the SASC in Balad.
    > It destroys the gun, and can injure the soldier."


    5-8 a week, god damn.
     
  23. Owen

    Owen Moderator Emeritus

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    Gonculators

    Ah, yes, gonculators. The first known use for the word gonculator was at Smith & Wesson. "Gonculators" was a jargon/slang term for the handheld computers used during the semi-annual physical inventory.

    Usage

    Owen: "Hey Timmah, Did you see all the gonculators next to the pistol office?"
    Brett: "Yeah, physical inventory is next week"
    Owen: "Darnit Timmah, I hate using those gonculators!"
    Brett: "HAHA, I never have to do inventory!"
    Owen: "That's because you were raised by wolves and can't count!"
    Craig: "Owen, can't you see Brett is doing something useful? Go back to your desk before I banish you to the range, and make you shoot .44's all day!"

    Owen scurries out...

    Later on, a young engineer named Owen started to use the term gonculator for any random doodad. He has spread the term through several gun companies, much as Typhoid Mary spread, uh, typhus. Apparently all of these companies have overcome the infection.
     
  24. bytor94

    bytor94 Member

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    That charging assembly is the one used for the M296 model of the .50 cal. This is the model used in a gun pod configuration on the OH-58D Scout helicopter.

    How do I know this you may ask? I work on them daily! Yes, if headspace is not set right very BAD JUJU! Makes pilots say bad words to the ground crew. :cuss:

    At least when this model is used, there is no one actually holding on to the weapon.
     
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