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Thread: M193 + 1/7 twist SBR = baffle-strike?

  1. #11
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    Quote Originally Posted by rsilvers View Post
    I don't see how that would be true. 55 grain is fine for 1/7 twist.
    Good. I just ordered a couple thousand rounds of it. Thanks for weighing in!

    If I may continue along this line of thought...50gr Barnes TSX 5.56...okay, too?
    Last edited by WS6; 07-31-12 at 11:26.

  2. #12
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    1/7 twist can shoot anything from 40-80 grains.

    1/8 - up to about 77 grains, depending on bullet length.

    1/9 can shoot up to 69 grain or so on longer barrels.

    1/12 is pretty much 55 grain and less.
    Last edited by rsilvers; 07-31-12 at 11:33.

  3. #13
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    Quote Originally Posted by rsilvers View Post
    1/7 twist can shoot anything from 40-80 grains.

    1/9 can shoot up to 69 grain or so on longer barrels but not necessarily on short barrels. 1/12 is pretty much 55 grain and less.
    Thanks! I know I have shot 40gr VMAX from a 1/7 twist and it did fine, I just didn't know if the lighter projectiles had more fleet yaw than safe near the muzzle before settling down with the higher twist rates, and how that translated to safe use of a suppressor, if it existed.

  4. #14
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    Quote Originally Posted by WS6 View Post
    Thanks! I know I have shot 40gr VMAX from a 1/7 twist and it did fine, I just didn't know if the lighter projectiles had more fleet yaw than safe near the muzzle before settling down with the higher twist rates, and how that translated to safe use of a suppressor, if it existed.
    google SS109/M855 development. It will give you some good insight on the development of the projectile and how the 1/7 twist came to be the standard.

  5. #15
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    Quote Originally Posted by Hydguy View Post
    google SS109/M855 development. It will give you some good insight on the development of the projectile and how the 1/7 twist came to be the standard.
    The ss109 was paired with the 1/9 twist rate when originally developed for the FN MINIMI. The tracer round burn distance was altered. 1/7 became necessary to accommadate the longer m856 round.

  6. #16
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    If its grouping well down range and nothing looks odd I would not worry about using 55 grain bullets.

    I use 55grain handloads pretty much exclusivly in my 12.5 with aac m4-2000.

    several thousand rounds of a mix of handloads, m193, and wolf. no baffle strike with my 1/7 12.5

  7. #17
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    2,000 suppressed rounds through LWRC M6A2 10.5" with Federal XM193 here. Zero baffle strikes on Surefire MINI and FA68K.

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