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Thread: 1/7 twist and 55 grain rounds

  1. #71
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    Ill post a range day thread when my dies come in. I never planned on hand loading for my ARs but prices are getting ridiculous for right now.
    Last edited by GUNSLINGER733; 12-27-12 at 02:24. Reason: ...
    rcsperformanceonline.com

  2. #72
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    Quote Originally Posted by Requiescat_in_Pace View Post
    sorry for reviving this thread but I have a 1 in 7 twist barrel on my custom AR15 and a friend has mentioned that if i shoot anything less than 65 grain it wears the rifling out faster? Is there a significant increase or is it not that noticeable?
    Lighter bullet weight alone will not cause an increase in wear and tear on a 1:7 barrel. Your friend might be referring to the opinion of some military personnel who noticed a reduction in barrel life with the 1:7 twist barrels, which was why the military adopted the 1:9 twist barrels for widespread use.

    I think you will find heavier bullets in the 62g-75g range will be more accurate than lighter bullets in the 45g-55g range when shooting run of the mill factory ammuntion. You can shoot tight groups with lighter bullets out of a 1:7 barrel if they are high quality bullets like the Hornady or Siera bullets, but a lot of folks shoot whatever is available like M193 ball. When I first started shooting high power, I shot a Colt HBAR with 1:7 barrel. The HBAR shot 55g bullets into 2-1/2 MOA 10 shot groups out to 300 yards and 1-1/2 MOA groups with 64g and heavier bullets.

    If you can shoot 3 MOA out to 300 yards with 55g bullets, I would not get too excited about buying more expensive ammunition if you are not shooting CMP matches.
    Last edited by 7 RING; 12-27-12 at 13:59.

  3. #73
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    Quote Originally Posted by 7 RING View Post
    Your friend might be referring to the opinion of some military personnel who noticed a reduction in barrel life with the 1:7 twist barrels, which was why the military adopted the 1:9 twist barrels for widespread use.
    Um, what?


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  4. #74
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    Quote Originally Posted by JBecker 72 View Post
    Um, what?


    Sent from my PC36100 using Tapatalk 2
    I got that information from members of the U.S Army Marksmanship Unit and the USMC Marksmanship Unit when I was at Camp Perry several years ago. They told me the 1:9 barrels lasted longer than the 1:7 barrels on the standard issue M-16s. We did not discuss the twist rate on the carbine barrels.
    Last edited by 7 RING; 12-27-12 at 14:52.

  5. #75
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    Quote Originally Posted by 7 RING View Post
    I got that information from members of the U.S Army Marksmanship Unit and the USMC Marksmanship Unit when I was at Camp Perry several years ago. They told me the 1:9 barrels lasted longer than the 1:7 barrels on the standard issue M-16s. We did not discuss the twist rate on the carbine barrels.
    They may have been running 1/9 barrels on AMU guns... but the M16 went from 1/12 to 1/7 to stabilize the M856 tracer. Never was there a 1/9.
    "You people have too much time on your hands." - scottryan

  6. #76
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    Quote Originally Posted by markm View Post
    They may have been running 1/9 barrels on AMU guns... but the M16 went from 1/12 to 1/7 to stabilize the M856 tracer. Never was there a 1/9.
    I stand corrected.

    Thank you.

  7. #77
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    From what I know and understand, bullet weight has little to do if anything with the twist rate of your rifling. It's the length of the projectile being fired. Heavier bullets tend to be longer and thus need a faster twist to be stabilized properly. Bullet weight alone has nothing to do with stabilization by rifling and that explains the wildy different results people are getting. Some bullets are longer than others due to their design/construction/materials used. Somebody correct me if I'm wrong here.
    Last edited by Shao; 12-27-12 at 19:29.

  8. #78
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    Quote Originally Posted by Shao View Post
    Somebody correct me if I'm wrong here.
    No.. you're exactly right.

    for example, 55 gr Frangibles are long but still require a 1/9 or faster twist to stabilize.
    "You people have too much time on your hands." - scottryan

  9. #79
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    Quote Originally Posted by Shao View Post
    From what I know and understand, bullet weight has little to do if anything with the twist rate of your rifling. It's the length of the projectile being fired. Heavier bullets tend to be longer and thus need a faster twist to be stabilized properly. Bullet weight alone has nothing to do with stabilization by rifling and that explains the wildy different results people are getting. Some bullets are longer than others due to their design/construction/materials used. Somebody correct me if I'm wrong here.
    Based on my personal experience, you are correct sir.

    I am surely not going to repeat anything I was told again. What you stated I have experienced first hand on the reloading bench and on the range.
    Last edited by 7 RING; 12-27-12 at 22:46.

  10. #80
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    Quote Originally Posted by Shao View Post
    From what I know and understand, bullet weight has little to do if anything with the twist rate of your rifling. It's the length of the projectile being fired. Heavier bullets tend to be longer and thus need a faster twist to be stabilized properly. Bullet weight alone has nothing to do with stabilization by rifling and that explains the wildy different results people are getting. Some bullets are longer than others due to their design/construction/materials used. Somebody correct me if I'm wrong here.
    I have some people telling me it has something to do with weight. Now I totally could c that your make a sense. Thank god for m4c forum! Always learn something new everytime I logged on here.

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