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Thread: Barrel length and twist rate for SBR?

  1. #1
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    Barrel length and twist rate for SBR?

    Being that I'm planning on starting an SBR build soon, I'm having trouble settling on a barrel.

    I don't feel particularly confident in picking a length and twist rate of barrel yet. As the velocity and twist rate of the barrel impacts the effectiveness of the round fired, I feel like there are a number of variables at work in choosing the most effective or versatile barrel.

    I've heard wonderful things about 70gr TSX rounds, but I'm not sure if they'll stabilize from an 11.5" 1:8 twist barrel. If they do, will they perform exceptionally well at that velocity still? What about a 62gr soft point?

    I'm looking to build an SBR that I plan to shoot as my main rifle, that will also serve as my HD gun. It would be nice if that combo that could well out to about 200 yards (ammo to match that barrel length).

    I had been leaning towards 11.5", but 12.5" seems to have some fans as well. At that point, I begin to question the hassle of going NFA for 2" less than a 14.5" gun with a pinned device...

    I guess my question is just: what length and twist rate seems to be the most versatile of the SBR's given ammo on the market today?

    Thanks in advance!

  2. #2
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    Being that I'm planning on starting an SBR build soon, I'm having trouble settling on a barrel.

    I don't feel particularly confident in picking a length and twist rate of barrel yet. As the velocity and twist rate of the barrel impacts the effectiveness of the round fired, I feel like there are a number of variables at work in choosing the most effective or versatile barrel.

    I've heard wonderful things about 70gr TSX rounds, but I'm not sure if they'll stabilize from an 11.5" 1:8 twist barrel. If they do, will they perform exceptionally well at that velocity still? What about a 62gr soft point? 1/7 and 1/8 have no issues with those weights at all. You should be fine with 55-77gr.

    I'm looking to build an SBR that I plan to shoot as my main rifle, that will also serve as my HD gun. It would be nice if that combo that could well out to about 200 yards (ammo to match that barrel length).

    I had been leaning towards 11.5", but 12.5" seems to have some fans as well. At that point, I begin to question the hassle of going NFA for 2" less than a 14.5" gun with a pinned device...
    Pinning a muzzle device is not very advisable unless you live somewhere like New York or NJ where you have to have a permed attachment. The 11.5 and 12.5" are the tits in my opinion and I use both uppers.

    I guess my question is just: what length and twist rate seems to be the most versatile of the SBR's given ammo on the market today?

    I would go with 1/7 and either an 11.5" or 12.5". Both will easily reach out to your 200 meters and beyond.

    Thanks in advance!



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  3. #3
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    It really depends on the function/purpose

    I've been running 12.5" 1:7 because of concerns over excess erosion of the blast baffle in my suppressors. Overall it works pretty darn well as far as balance and performance of ammo/terminal performance.

    I always though the Noveske Diplomat is cool but wouldn't want to run something that short unless it was for specific tasks.
    Last edited by Loki; 01-06-13 at 14:14.

  4. #4
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    Barrel length and twist rate are almost irrelevant these day.

    Barrel length: With the modern bullets (bonded and TSX), there is no need to be concerned about length (as these bullets do not rely on speed to do their damage).

    Twist rate: Quality bonded and TSX bullets range from 50gr to 70gr. So if you are using any of the popular twist rates, you are good.


    For me, I would go with a 10.5 with a 1/7 or 1/8 twist.




    C4

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    Quote Originally Posted by C4IGrant View Post
    Barrel length and twist rate are almost irrelevant these day.

    Barrel length: With the modern bullets (bonded and TSX), there is no need to be concerned about length (as these bullets do not rely on speed to do their damage).

    Twist rate: Quality bonded and TSX bullets range from 50gr to 70gr. So if you are using any of the popular twist rates, you are good.


    For me, I would go with a 10.5 with a 1/7 or 1/8 twist.




    C4
    This is my stance, as well. Plenty of projectiles in .223/5.56 that will expand to double their caliber out to 200+ yards from a 10.5" SBR.

    My 64Gr Gold Dot being one of them, and it leaves a 10.5" tube doing 2500+fps.

    Noveseke's stance on it, when I spoke with them, was that their 10.5" guns are just as reliable as their 12.5" guns. I have yet to see someone who disagrees and HAS AN EXPERIENCE TO DEMONSTRATE.
    Last edited by WS6; 01-06-13 at 19:16.

  6. #6
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    I disagree to a point. The 10.5" in many cases need to be opened up in order for them to run reliably with anything other than real 5.56 ammo. That's not conjecture.

    I did alot of reading when I got my first upper and I chose the 11.5" because the loss of an inch was less important than function and reliability. Thus far it has proven to be 100% reliable.

    Quote Originally Posted by WS6 View Post
    This is my stance, as well. Plenty of projectiles in .223/5.56 that will expand to double their caliber out to 200+ yards from a 10.5" SBR.

    My 64Gr Gold Dot being one of them, and it leaves a 10.5" tube doing 2500+fps.

    Noveseke's stance on it, when I spoke with them, was that their 10.5" guns are just as reliable as their 12.5" guns. I have yet to see someone who disagrees and HAS AN EXPERIENCE TO DEMONSTRATE.



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  7. #7
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    Quote Originally Posted by Iraqgunz View Post
    I disagree to a point. The 10.5" in many cases need to be opened up in order for them to run reliably with anything other than real 5.56 ammo. That's not conjecture.

    I did alot of reading when I got my first upper and I chose the 11.5" because the loss of an inch was less important than function and reliability. Thus far it has proven to be 100% reliable.
    Is this your experience with Noveske 10.5" sbr's? I have not heard this about them.

  8. #8
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    Not with Noveske per se and I have no idea what size port they use. But they aren't the only 10.5" in town.

    Quote Originally Posted by WS6 View Post
    Is this your experience with Noveske 10.5" sbr's? I have not heard this about them.



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  9. #9
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    I had been leaning towards 11.5" because I thought 10.5" would beat on a suppressor a little too hard if I went that route, so it seemed like 11.5" might be the shortest I could go and still not have to worry as much about that.

    I had mentioned 1:8 twist since that's how BCM is offering their 410 stainless barrels, but I forgot about the 1:7 Noveske's.

    The likelihood of my buying a suppressor is pretty low, so maybe I should just get the 10.5" and later if I do get a suppressor, build a suppressor upper for that gun and use it on the same SBR'ed lower (11.5" with adjustable gas block) or SBR a second lower at that point.

    I'd like this to be what I shoot the most often, so I'm looking to get the best lifespan and accuracy from the barrel I can get, so buying a higher end barrel is certainly an option for me.

    Thanks

  10. #10
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    Quote Originally Posted by Jim D View Post
    I had been leaning towards 11.5" because I thought 10.5" would beat on a suppressor a little too hard if I went that route, so it seemed like 11.5" might be the shortest I could go and still not have to worry as much about that.
    They all do (honestly). This is why you run a MB with a can (as it acts as the first baffle).

    The likelihood of my buying a suppressor is pretty low, so maybe I should just get the 10.5" and later if I do get a suppressor, build a suppressor upper for that gun and use it on the same SBR'ed lower (11.5" with adjustable gas block) or SBR a second lower at that point.
    This is a mistake IMHO. If I was king, it would be ILLEGAL to operate and SBR without a can on it. Get a can Jim!


    C4

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