AR pistol upper 11.5 or 12.5?

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  • venenoindy

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    I'm getting ready to order a pistol upper from BCM and still can't decide if I should go with 11.5 or 12.5, this pistol will be use at a maximum of 200 yes and CQB. Want it to be as reliable as possible, should I wait to order during Black Friday sales?.
     

    rkwhyte2

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    Either will work fine. I went with the BCM 12.5" Kino configuration upper. Love it.
    IEckfkB.jpg
     

    rosejm

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    Besides the obvious, what's the difference? :dunno:
    Not clear to me that the extra inch makes any difference for an AR.
     

    Hop

    Grandmaster
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    My bcm 11.5 wouldn't lock back until I added a heavier Spikes buffer. I'll assume that it was bouncing off the rear of the receiver tube and traveling too fast to get caught by the latch.

    It's working great now. Accuracy is also good.

    Sent from my SM-G935V using Tapatalk
     

    venenoindy

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    Besides the obvious, what's the difference? :dunno:
    Not clear to me that the extra inch makes any difference for an AR.

    I done some research and from what I understand the shorter the barrel the less velocity the round will have, with 5.56 you want all the velocity possible for the round to be effective. Also very important what type of round you will be using.
     

    Mustang1911

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    Two advantages to the 12.5 over the 11.5: longer dwell time and slightly more velocity. Both are good reasons to me to go with the 12.5.

    More dwell time will theoretically give you a slight edge in reliability since the bullet in in the barrel slightly longer which gives the gasses a bit more time to cycle the gun. The gun can then run with a slightly smaller gas port which can decrease the recoil impulse.

    Also more velocity will give the bullet a better chance of fragmenting out to longer ranges. Non expanding 556/223 rounds require fragmentation to be effective.

    IMO the one inch longer barrel isn’t enough of a hindrance to negate the advantages.
     

    rosejm

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    While that's all true, 1" will not make an appreciable difference. You're talking maybe 100-150 fps if we're generous.
    I'd buy this if we were talking 20" vs. 14.5" and double that distance or further.

    Won't really matter, because from 0-200 the fireball will be plenty big enough to overcome that reduced muzzle velocity.
     

    Tactically Fat

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    I'm in the same boat right now. Exact same boat as I was looking through BCM's website earlier today, as a matter of fact.

    I'm leaning towards 12.5 due to A) the ever-so-slight reduction in recoil impulse (not that there's much from 5.56x45 anyhow) and B) so it'll be that much more gentle on a suppressor's blast baffle.
     

    Sniper 79

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    I'm in the same boat as well. All I ever shoot is inside of 150 yards. My rifles have lived a life in the back of the safe. I have one more 18" gun to sell off and I'm done with long guns.

    I went over to a shop and handled some nice 11.5" guns. What a nice handy size! I want one something fierce! Sure would like to shoot one before 1k plus leaves my bank account.
     

    venenoindy

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    I'm in the same boat as well. All I ever shoot is inside of 150 yards. My rifles have lived a life in the back of the safe. I have one more 18" gun to sell off and I'm done with long guns.

    I went over to a shop and handled some nice 11.5" guns. What a nice handy size! I want one something fierce! Sure would like to shoot one before 1k plus leaves my bank account.

    If I complete mine soon you are welcome to put a few rounds through.
     

    indygunguy

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    I have a BCM 11.5" and it's great. I went back and forth about the 12.5 vs 11.5 and decided that the whole purpose of this "pistol" was to be short and lightweight, so I went with 11.5".
     

    AngryRooster

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    I'm in the same boat as well. All I ever shoot is inside of 150 yards. My rifles have lived a life in the back of the safe. I have one more 18" gun to sell off and I'm done with long guns.

    I went over to a shop and handled some nice 11.5" guns. What a nice handy size! I want one something fierce! Sure would like to shoot one before 1k plus leaves my bank account.

    I like my BCM 11.5". Will be doing the efile form 1 probably tomorrow. It's in pistol configuration right now. If you want to check it out and shoot it we may be able to work something out. I'm on the east side of the state, Randolph Co, but can travel a bit.
     

    Kperkins

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    Dec 6, 2018
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    I have an 11.5 because it was easy to get at that time. I’ve enjoyed it. Not intended to use past 150 or so. I’m impressed with how soft it shoots compared to what I was expecting
     

    NyleRN

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    I'm in the same boat right now. Exact same boat as I was looking through BCM's website earlier today, as a matter of fact.

    I'm leaning towards 12.5 due to A) the ever-so-slight reduction in recoil impulse (not that there's much from 5.56x45 anyhow) and B) so it'll be that much more gentle on a suppressor's blast baffle.

    *laughs in stellite*
     

    2Lucky

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    The shorter the barrel the more "tweeking" you will have to do. Also its best in shorter barrel is to settle on a specific brand or load if you reload.
     

    firefighterjohn

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    This is what I'm kind of up against. Do I spend BCM money... Or do I go with a 11.5" quality upper and save $200?

    Ran across this thread since I'm also considering a 11.5 BCM complete pistol. So what did you end up deciding on? What lower did you put it on. Also curious to hear how it's run so far and how you like it? Thanks in advance!
     
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