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  • j_h_smith

    Ultimate Member
    Jul 28, 2007
    28,516
    Thanks to Flatsflite and his Classified ad, I will be building a 50 Beowulf SBR with a 10.5" barrel. I'll post pictures when I receive the upper as soon as I get it(hopefully on Monday).

    I've been looking to do this for some time. I tried talking to Alexander Arms about a 10.5 inch barrel and they almost hung up on me.

    Am I insane for building a flame thrower?

    I wonder what grain bullet is going to be the most accurate for that barrel length? Looks like I'm going to have to do some research on something that isn't going to have much information on the subject.

    Wish me luck!
     

    mtlcafan79

    Ultimate Member
    Sep 11, 2008
    1,279
    PG
    Just think single stack in a regular mag. 458 SOCOM headspaces on the neck, 450 bushmaster and 50 beowulf headspace off the case. Other than that they function the same as any other gas operated AR.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    Just think single stack in a regular mag. 458 SOCOM headspaces on the neck, 450 bushmaster and 50 beowulf headspace off the case. Other than that they function the same as any other gas operated AR.

    :thumbsup: Tanks!
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,644
    MoCo
    I tried talking to Alexander Arms about a 10.5 inch barrel and they almost hung up on me.

    Am I insane for building a flame thrower?

    Not much different than a 8" S&W500 (which actually has a little more case capacity and almost 2x the pressure.) Lots of avail powders can burn fast enough to utilize a 10" bbl. Question is how fast can you get the lead moving in the allowed case pressure. Remember that big diameter bullets will accelerate faster for the same pressure than small ones. Black powder guys figured that out LONG ago.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    Remember that big diameter bullets will accelerate faster for the same pressure than small ones. Black powder guys figured that out LONG ago.
    Interesting. Is that because of increased surface area for gas to push on?
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,644
    MoCo
    Yes. 500 is 2.24x larger diameter than 223 so it has 5x the area (and thus force accelerating it for the same psi.) Of course you tend to run much heavier bullets so that counteracts much of it. But because of the burn rate/pressure limitations of black powder they had to increase diameter vs pushing small bullets faster. 45 Colt and 45-70 were big for a reason :)
    IIRC, 50 beowulf is 30-something ksi. About half 5.56 or 500 S&W. The bolt lug thrust is the limiting factor (true for anything limited to the AR15 bolt lug diameter.)
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    Yes. 500 is 2.24x larger diameter than 223 so it has 5x the area (and thus force accelerating it for the same psi.) Of course you tend to run much heavier bullets so that counteracts much of it. But because of the burn rate/pressure limitations of black powder they had to increase diameter vs pushing small bullets faster. 45 Colt and 45-70 were big for a reason :) IIRC, 50 beowulf is 30-something ksi. About half 5.56 or 500 S&W. The bolt lug thrust is the limiting factor (true for anything limited to the AR15 bolt lug diameter.)

    Huh. Surprised there isn't more focus on dimpling/hollowing out/tapering bullets to increase SA and increase acceleration. Of course, I'm sure it's been thought of.
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,644
    MoCo
    Instead of hollowing just use a different, less dense, material. The super long range guys use machined copper bullets AFAIK. The machining from a homogeneous solid gives it excellent spin balance. Something other than lead makes it lighter than normal for the diameter and they can use long profiles for high BCs w/o slowing the bullet down. But we are getting off topic... ;)

    I really want to build a 50 Beo. I shot bradmac's 50 once @ Delmarva. Shot a friends 458 SOCOM too. Hard to decide as I have reloading supplies for both diameters already. I don't have a suppressor for either however.:evilgrin3
     

    j_h_smith

    Ultimate Member
    Jul 28, 2007
    28,516
    I think I'd be best to start with manufactured ammo. Do you think the lighter grain bullets will stabilize and spin better than a heavier bullet in this short barrel. My 16" shoots all bullets well, but I don't know if I'm going to get that with this 10.5 inch barrel.
     

    SCARCQB

    Get Opp my rawn, Plick!
    Jun 25, 2008
    13,614
    Undisclosed location
    10.5” beowulf sbr.

    Set up as a PDW.
     

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