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Thread: Barrel hood movement at lockup

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  1. #1

    Barrel hood movement at lockup

    I have a GI model Springfield, appx 1500rds made in 2009. I have it at SACS for work other than repairs when I asked the shop this question (paraphrased):

    My barrel has downward movement at lockup, it seems to be minimal but it's there, I don't have any way to measure it. It's my understanding that there should be no movement

    Response: "It is normal in the GI models for there to be some movement in the factory barrel."


    Is this correct? I'm simply seeking a second opinion...thanks!

  2. #2
    Join Date
    23rd September 2008
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    Quote Originally Posted by VinnAY
    I have a GI model Springfield, appx 1500rds made in 2009. I have it at SACS for work other than repairs when I asked the shop this question (paraphrased):

    My barrel has downward movement at lockup, it seems to be minimal but it's there, I don't have any way to measure it. It's my understanding that there should be no movement

    Response: "It is normal in the GI models for there to be some movement in the factory barrel."


    Is this correct? I'm simply seeking a second opinion...thanks!
    Hello,

    If I understand your comments correctly then then ......Yes....absolutely yes....

    Only match fit barrels have full hard contact at lockup. Most other 1911s have barrel lugs that allow the barrel lugs to CAM along the lug-to-barrel-lug contour. This means that when the barrel is in full battery the barrel may slide back along the slide stop if you push down on the barrel hood while in battery.

    Here is a production Colt barrel lug profile:


    Notice how steep the lug profile is?

    Try pushing forward on the back of the slide while pushing down on the barrel hood to see if there is really any movement.

    Rgds
    Eric

  3. #3
    thank you, Sir

  4. #4
    Join Date
    25th September 2006
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    The vertical play at the ejection port for a Gov't Issue M1911 is a function of the play in the barrel's link system. That play is 0.010" for the average gun.

    Regards
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

  5. #5
    I'd say that I'm in the .010 play area....I continue to learn something new everyday about the 1911...which much help

  6. #6
    Very interesting.
    I recently bought an unfired Norinco 1911A1 and THEN found out about the barrel lug peening problems some have. So, I have been learning more about 1911 barrel lock up then I ever thought possible.
    After reading this thread, I did as suggested above, and pushed forward on the slide while trying to push down on the barrel hood...zero movement.
    I have only put about 75 rounds through this previously unfired Norinco so far...I looked closely at the lugs when I cleaned it, and see nothing unusual..so far.

  7. #7
    Join Date
    25th September 2006
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    Quote Originally Posted by amd6547
    After reading this thread, I did as suggested above, and pushed forward on the slide while trying to push down on the barrel hood...zero movement.
    Don't let the results of this particular test fool you into believing your barrel has zero up & down play when in battery. Get yourself a piece of wood dowel about 2 feet long that's just small enough to fit down the barrel.

    Put the dowel down the barrel, put the other end of the dowel under a bench or heavy table, grip the gun normally, raise the front sight up hard (this will apply upward pressure on the aft end of the barrel), pull the slide aft just a little, let it go back to battery then remove the dowel.

    If all that's done correctly the aft end of the barrel is up as high inside the slide as it can get and the recoil spring, through the slide, is holding it there.

    Lastly, push down on the top of the barrel through the ejection port and see if you've still got zero movement. You should have some now.

    Regards
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

  8. #8
    OK...assuming I did this (I have not...yet) and still found zero movement...Good? Bad?

  9. #9
    Join Date
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    Location
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    13,113
    Quote Originally Posted by amd6547
    OK...assuming I did this (I have not...yet) and still found zero movement...Good? Bad?
    Miraculous. Simply miraculous!

    Regards
    When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. [Lord Kelvin]

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