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  1. #1
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    Downside to cutting Bob off Ar-15 Hammer???

    I have a RRA lower with the bobtailed hammer. I recently purchased the CMMG .22 kit. Works fine. Now I want to lighten up my trigger with some JP yellows. Word has it that I will get light strikes and I need to cut the bob off my hammer on the lower to increase the speed of the hammer so I can continue to use the CMMG conversion bolt without light strikes.

    My question is this: "Is there any downside to cutting the bob off the hammer to lighten the load?" Will it create any problems when I switch back to .223 of 556.? If there is no downside, why doesn't everyone do it?

  2. #2
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    What are "jp yellows"?
    -Pete
    Greyhound Station, Downtown Houston

  3. #3
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    Cutting the "bob" off will cause light strikes, not correct it. You're reducing the mass of the hammer, which means it stops moving more easily when it hits the firing pin. About the only downside to trimming the hammer down is the potential for light strikes, mostly in military surplus ammo (extra-hard primers). Usually runs fine with commercial ammo.

    The only reason to cut it off is to reduce lock time.
    Don't mind me, I'm just making sure I'm on all of the watch lists.

  4. #4
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    Quote Originally Posted by TXSUT View Post
    What are "jp yellows"?
    Yellow trigger and hammer spring kit from JP Enterprises. IIRC, it's the kit that yields a 4 lb trigger pull.
    Don't mind me, I'm just making sure I'm on all of the watch lists.

  5. #5
    LJH
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    Cutting the tail from the hammer is an old trick. It does speed up lock time, (shortens the time the hammer is in motion). You should be able to use the modded hammer with any ammo. The reason not everyone does this is because some people say hard primers will not pop with the lighter hammer, (think wolf ammo). I have cut tails on every one of my AR hammers and have never had a failure.

    If you are interested I can post up a decent write up on tunning AR triggers.
    Sig no more

  6. #6
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    Quote Originally Posted by LJH View Post
    If you are interested I can post up a decent write up on tunning AR triggers.
    You have to ask?
    Don't mind me, I'm just making sure I'm on all of the watch lists.

  7. #7
    LJH
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    Quote Originally Posted by M. Sage View Post
    You have to ask?
    On it !
    Sig no more

  8. #8
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    Thanks!

  9. #9
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    Just bobbed the hammer in my AR, we'll see how it functions.
    Don't mind me, I'm just making sure I'm on all of the watch lists.

  10. #10
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    Re: Downside to cutting Bob off Ar-15 Hammer???

    bobbed hammer, JP trigger and both JP yellow (reduced tension) springs in EVERY AR I own, including the dedicated .22, and they all run.

    its the combination of the components that is the key. if you simply went with the reduced tension springs on a stock hammer then you would have the same mass being affected by less potential stored energy. now light spring + light hammer = roughly the same force being applied to the firing pin as full size hammer and OEM springs (more mass being driven by a stronger spring).

    if you decide you dont want those pesky yellow springs, send em over here.

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