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Thread: What buffer to use with UBR - 18 inch barrel

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    What buffer to use with UBR - 18 inch barrel

    I think this belongs in the technical discussion. (my first thread i believe)...
    I was just wondering what buffer i would need/want to use with a Magpul UBR if i were to put one on my lower to use with an 18" rainier upper. I have an A2 stock on it now so obviously i need a carbine buffer, but how heavy? this is the one topic that is very unclear to me after all of my reading about ar15's. thanks for the responses.

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    Quote Originally Posted by Biz Kizzle View Post
    I think this belongs in the technical discussion. (my first thread i believe)...
    I was just wondering what buffer i would need/want to use with a Magpul UBR if i were to put one on my lower to use with an 18" rainier upper. I have an A2 stock on it now so obviously i need a carbine buffer, but how heavy? this is the one topic that is very unclear to me after all of my reading about ar15's. thanks for the responses.
    H or H2 would feel good on it.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    thanks for the quick response. i figured a bit more weight would be needed.

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    What length gas system does the Rainer 18" upper have?

    If it is a mid-length the gotm4 is spot on, as usual, to run an H or H2.

    I have an 18" BCM upper with the rifle length gas system, and the UBR, and the recommendation from BCM was to run an H3 buffer, and it runs very well.

    Cameron
    Last edited by Cameron; 08-13-10 at 01:34.

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    My 18" Noveske w/ intermediate gas runs nice with a standard CAR buffer, but I am using an AR15 (not M16) cut FailZero BCG, and a DNTC comp.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

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    Quote Originally Posted by Cameron View Post
    What length gas system does the Rainer 18" upper have?

    If it is a mid-length the gotm4 is spot on, as usual, to run an H or H2.

    I have an 18" BCM upper with the rifle length gas system, and the UBR, and the recommendation from BCM was to run an H3 buffer, and it runs very well.

    Cameron
    well its a rifle length gas sytem actually so maybe i need a heavier buffer than i thought? i'm using a spikes m16 bcg btw
    Last edited by Biz Kizzle; 08-13-10 at 14:00. Reason: spelling...

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    I hate to jump in here but I have almost the same question about buffer/spring combo for my 20" rifle length upper. I have a BCM BCG and a cavarms lower. Should I use a rifle spring and buffer combo or use a carbine spring and a H2 or H3 buffer.
    "We prepare, so we don't end up at the superdome"- unknown

    "IMHO, if you wanted to shoot crap ammo, you should have bought a crap upper. It makes baby Jesus cry when he sees crap ammo put through a nice upper."- C4IGrant

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    Quote Originally Posted by sewvacman View Post
    I hate to jump in here but I have almost the same question about buffer/spring combo for my 20" rifle length upper. I have a BCM BCG and a cavarms lower. Should I use a rifle spring and buffer combo or use a carbine spring and a H2 or H3 buffer.
    If using a rifle length stock the standard rifle buffer and spring would be fine. If using a carbine stock I'd recommend a H2 and spring, possibly even a H3.
    The new VLTOR USMC A5 EMOD stock assy is very nice too and purpose built for 18"-20" barrels. I'm using on my BCM 16" midlength and it's very nice. It uses an extended length receiver extension, rifle length buffer spring and a 5oz special length buffer.
    Last edited by Robb Jensen; 08-13-10 at 14:56.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

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    Quote Originally Posted by gotm4 View Post
    If using a rifle length stock the standard rifle buffer and spring would be fine. If using a carbine stock I'd recommend a H2 and spring, possibly even a H3.
    The new VLTOR USMC A5 EMOD stock assy is very nice too and purpose built for 18"-20" barrels. I'm using on my BCM 16" midlength and it's very nice. It uses an extended length receiver extension, rifle length buffer spring and a 5oz special length buffer.
    i actually decided that my next stock will be either a UBR or the vltor a5.
    whats the weight on the a5 like? and it works well with a 16 inch midlength upper?
    that's the next upper i'd build and it'd be used on this lower so it'd be good to know.

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    BCM 18" barrel rifle length gas with UBR stock and H3 buffer (inside)...



    This was the recommended weight from Bravo Company and it runs very smoothly.

    Cam

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