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  1. #1

    Default How does open bolt work

    Does anybody have any anmations of on working?
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  2. #2
    Try doing a google or youtube search, theres lots of websites out there. Basically a gun that fires open bolt has a firing pin that is fixed in the bolt, the bolt slamming closed fires the round, gas pressure reopens the bolt and it is held open until the trigger is pressed again. Prevents the chamber from getting to hot after firing full auto.
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  3. #3
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    http://www.youtube.com/watch?v=bb4GW...e_gdata_player

    Maybe that answers some questions.... Nothing specific but like it was said above, fixed firing pin, trigger just holds the bolt open or let's it keep going if its held down...

  4. #4
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    Quote Originally Posted by Jons999 View Post
    Basically a gun that fires open bolt has a firing pin that is fixed in the bolt, the bolt slamming closed fires the round
    While some open bolt guns have fixed firing pins, this is not true of all open bolt designs. Some have more conventional firing pin setups.

  5. #5
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    Quote Originally Posted by Chris Upchurch View Post
    While some open bolt guns have fixed firing pins, this is not true of all open bolt designs. Some have more conventional firing pin setups.
    Example??? While I have a M-11 bolt with a removable firing pin as opposed to a bolt for the same M-11 with the firing pin fixed(milled) in the bolt, I can't recall any open bolt MG's with a conventional firing pin arrangment. Not saying there isn't...just that none come to mind.

    Maybe a little more detail for the OP would help....The bolt is held to the rear and released when you pull the trigger...as the bolt moves forward it picks up a round from the magazine....the round is chambered as the bolt follows it forward and the fixed (in most cases) firing pin ignites the primer. Most (if not all) open bolt MG's are blowback in operation so there is no lockup. The weight of the bolt holds the round in the chamber long enough for safe pressures to be achieved before the bolt is "blown" back open, dragging the now empty case along with it....repeat as needed..

  6. #6
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    Quote Originally Posted by dtom29 View Post
    Example???
    The M240/M249 and PKM are open bolt designs that feature non-fixed firing pins.

    Quote Originally Posted by dtom29 View Post
    Most (if not all) open bolt MG's are blowback in operation so there is no lockup.
    While that's true of most open bolt submachineguns, open bolt machine guns are most commonly gas operated, followed by recoil operated and a few roller-locking designs. Full power rifle cartridges are just too powerful for straight blowback operation.
    Last edited by Chris Upchurch; 01-30-2012 at 09:31 AM.

  7. #7
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    Thanks Chris, I didn't know about M240/249 and the pkm.
    You're right, I was referring to Submachineguns. I should have said that. I was trying to keep it simple as I could for the OP.

  8. #8
    The M1 Thompson has a "floating" firing pin, whereas the M1A1 Thompson has a fixed firing pin. Both fire from an open bolt.

  9. #9
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    Quote Originally Posted by Chris Upchurch View Post
    The M240/M249 and PKM are open bolt designs that feature non-fixed firing pins.
    As does the original 1918 BAR that the 240 is largely a derivative of.
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  10. #10
    Add M-60.

    Choirboy

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