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Thread: .223, rate of twist, and barrel length

  1. #1
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    .223, rate of twist, and barrel length

    So what's the scoop on .223 out of a short barrel?
    How will a 1:7 twist rate work for stabilizing heavier bullets, and how will a short (8-in.) barrel effect bullet stabilization?
    How much poop does one lose when shooting .223 out of, say, an 8-in. to 10-in. barrel?
    Thoughts? Experience?
    Thanks.
    The gun-toting practitioner of the Middle Path.

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    Moderator & Team Gunsnet Platinum 07/2011 O.S.O.K.'s Avatar

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    Here's a good link for you: http://forums.officer.com/forums/arc...hp/t-9548.html

    Everything I've read indicates that you lose pretty much everything that makes the .223 a capable catridge when you go short...
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  3. #3
    Forum Administrator Schuetzenman's Avatar

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    I would suspect that a 10" barrel will reduce the .223 to not much better than a .38 spl. in power.

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    Quote Originally Posted by O.S.O.K. View Post
    Here's a good link for you: http://forums.officer.com/forums/arc...hp/t-9548.html

    Everything I've read indicates that you lose pretty much everything that makes the .223 a capable catridge when you go short...
    Interesting read! I sort of expected as much, really. I think my barrel has a 1:7 rate of twist, so conceivably it will spin a heavy bullet fast enough to stabilize it ... but I'm sure there's a nasty velocity loss with the heavy bullets...
    I also measured out the barrel ... looks like 9.5 in. will get it short enough to install the muzzle device without interfering with it. Anyone have a suchka that they'd take a photo of (without the muzzle device) for reference?

    ETA: Another interesting article...
    http://www.ar15.com/forums/announcement.html?b=3&f=16&id=162" target="_blank">http://www.ar15.com/forums/announcem...=3&f=16&id=162
    Last edited by AK again; 02-17-2011 at 10:32 PM.
    The gun-toting practitioner of the Middle Path.

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    I would love to see this on the box o truth.

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    Moderator & Team Gunsnet Platinum 07/2011 O.S.O.K.'s Avatar

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    Stabilization is affected by velocity, so I would expect that you'd need to back off of the weight some even with the 1:7 twist rate.... like no more than 69 grain match bullets...

    If you're handloading, you may be able to improve your performance by going with a faster burning powder... I'd look at data for Contenders to see what's worked for them.
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  7. #7
    I've chrono'ed 223's from a 7 inch barrel and got close to 2000 fps, at that velocity I'd just buy a 22 mag pistol and have a much more compact package. I suspect 2000-2200 FPS is obtainable which really hurts all I want from the 223. If I was going the SBR route I'd go with a 762x39 which isn't hurt nearly as much as the 223 is from a short barrel.

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    The more I think about it, the more I consider only lopping it off to 10 or so...
    It'll be a month before I put in paperwork. I'll keep everyone posted ...
    Someone at work suggested that I work up some loads with pistol powders and see what happens...
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  9. #9
    With barrels that short I wouldn't worry too much about stability.

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    LOL. .
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  11. #11
    Senior Member abpt1's Avatar

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    A 75gr HPBT will do the job out of10in barrel @2000fps IMHO.... I shoot my pistol up to 100yds np .

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    Stablization issues could start past 100 yards - it could be good to past 200 yards and then the bullets start to yaw. Are the holes in the target at 100 yards all nice and round or any oblong?
    ~Nemo me impune lacessit~
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  13. #13
    Senior Member gunslinger's Avatar

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    Stabilization is a matter of angular velocity (rpm).
    Barrel's length may or may not have influence on speed.
    It all depends upon powder's burning rate and bullet sectional density.
    Given the same bullet shape and construction (which may have a very strong effect on bullet center of gravity placement) a high sd bullet will require more rpm to be stabilized, and will require a slower burning powder to reach proper speed without risking dangerous pressures.
    With a proper load, even a short barrel can have something to say.

    Shooting a 158 grainer loaded with WW 296 out of a 6" barrel will give a very powerful load.
    Shoot it out of a 4" barrel and you'll loose much of it's punch.
    Shooting it in a 2" barrel is a good way to have a bullet with the power of a .32 and a very good flamethrower.
    But if you load that same 357 with 110 grains bullets, and a good load of fast burning powder (let's say WW 231) and you can get pretty decent or even good performance even out of a 2" barrel.

    So, going back to your 223: short barrels mean greater loss of muzzle velocity with heavier bullets. This means that the bullet will have a shorter range (when it goes subsonic, accuracy is lost).
    Since a short barrel limits your long range velocity, and so accuracy, shooting lighter bullets with faster powder can yeld more power, velocity and accuracy than firing a heavier bullet, even if the heavier bullet can carry it's lower initial velocity further due to superior BC.
    It's difficult to foresee what will yeld the better results.
    Best advice is to get a chronometer, some decent ballistic program and draw some trajectories, and velocity values at various distances, to see what works for you.
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    Unless a Yugo M-92 or SLR-107UR falls in my lap, I'll be reporting on the shorty .223 AK to you all within the year.
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  15. #15
    Senior Member abpt1's Avatar

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    Quote Originally Posted by O.S.O.K. View Post
    Stablization issues could start past 100 yards - it could be good to past 200 yards and then the bullets start to yaw. Are the holes in the target at 100 yards all nice and round or any oblong?
    no idea haven't shot paper yet only cans/pins but it hits them ...

  16. #16
    Senior Member gpwasr10's Avatar

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    Quote Originally Posted by Schuetzenman View Post
    I would suspect that a 10" barrel will reduce the .223 to not much better than a .38 spl. in power.
    THIS

    The 5.56 disturbing wound channels happen at velocities as near to 3000 fps you can get. Not that I would wanna be shot with one doing 2400 FPS., but still.

    But if you absolutely NEED a 5.56 in a length shorter then 16", go with the 1:7 cause you are going to want to shoot the heaviest pill you can load.. unless this is a "fun gun" then just get the cheapest barrel you can find and go to it.
    "Verily, I have often laughed at the weaklings who thought themselves good because they had no claws."
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  17. #17
    Senior Member Helen Keller's Avatar

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    I have a 11.5 barrel on my gun

    IF I take my time with handloads I can shoot just as good as I can within 300yds with a 20" gun.


    I have done extensive testing/shooting with various weights/loads out to 700yds . Im working on a 75gr BTHP load for this weekend to see what it can do.




    For the Kommandos sake:

    Penetration is still good at 300yds with heavier loads, IF I had to I would pick my bulgy Ak74SU SBR over my 11" SBR AR any day of the week between the two if I had to shoot more than 500 yds and make it count.
    I KILL WHITE PEOPLES LIKE YOU

  18. #18
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    @ Hellen: AKS-74U in the original 5.45? Or are you talking .223?
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