1/7 Twist or 1/9 Twist in a 16" AR15 Barrel..............

This is a discussion on 1/7 Twist or 1/9 Twist in a 16" AR15 Barrel.............. within the Defensive Rifles & Shotgun Discussion forums, part of the Related Topics category; Ok my question is this: I have a Palmetto State Armory 16" upper with a 1/7 twist rate 5.56 barrel, I've had some people tell ...

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    Member Array Christopher67's Avatar
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    Question 1/7 Twist or 1/9 Twist in a 16" AR15 Barrel..............

    Ok my question is this: I have a Palmetto State Armory 16" upper with a 1/7 twist rate 5.56 barrel, I've had some people tell me that the 1/9 twist is better for lighter bullets(50, 55gr & lighter), any truth to this? I was under the impression that with my 1/7 twist I could shoot 50gr - 75/77gr am I wrong? Also wouldn't the 1/7 be better at say the 200-300yd range? Thanks in advance.

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    VIP Member Array LimaCharlie's Avatar
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    Yes, a faster twist stabilizes heavier bullets better, especially out of a shorter barrel.
    I carry a gun, because a Cop is too heavy.

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    VIP Member Array pittypat21's Avatar
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    A 1/7 will handle 55gr bullets just fine. 1/7 is great for heavier bullets as well, while 1/9 will stabilize lighter bullets better.

    55gr should be fine for either one. But if you're going to shoot the heavier stuff, 1/7 will serve you well.

    If you really want to know how it performs, though, get some different ammo and run some tests!
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    Member Array Christopher67's Avatar
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    Quote Originally Posted by LimaCharlie View Post
    Yes, a faster twist stabilizes heavier bullets better, especially out of a shorter barrel.

    So a 1/7 twist in a 14.5" barrel would be better then the same twist in a 16" barrel?

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    Member Array Christopher67's Avatar
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    Quote Originally Posted by pittypat21 View Post
    A 1/7 will handle 55gr bullets just fine. 1/7 is great for heavier bullets as well, while 1/9 will stabilize lighter bullets better.

    55gr should be fine for either one. But if you're going to shoot the heavier stuff, 1/7 will serve you well.

    If you really want to know how it performs, though, get some different ammo and run some tests!


    I had a local Cabelas employee tell me that shooting a 50-55gr bullet out of a 1/7 twist wouldn't hold together once it left the barrel, not to mention he was rather rude & would elevate his voice while talking to me lol.

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    VIP Member Array pittypat21's Avatar
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    I think he means a 1/7 will stabilize heavier bullets better than a 1/9 - especially out of a shorter barrel.

    The twist rate is going to have an effect on accuracy, depending on the bullet weight and longer barrels are always going to be more accurate than shorter barrels.
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    VIP Member Array Rob99VMI04's Avatar
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    Quote Originally Posted by Christopher67 View Post
    I had a local Cabelas employee tell me that shooting a 50-55gr bullet out of a 1/7 twist wouldn't hold together once it left the barrel, not to mention he was rather rude & would elevate his voice while talking to me lol.
    hes an idiot!
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    Distinguished Member Array 5lima30ret's Avatar
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    Your 1/7 barrel should be fine! My S&W M&P-15 Sport has a 1/8 barrel and it does well with 45gr-69gr bullets. Good luck!
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    VIP Member Array peckman28's Avatar
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    I've shot plenty of 55-gr ammo from my 1/7 twist rifles. I've noticed no difference at 50 and 100 yards between that and the 1/9 rifles I own. If you've already got a 1/7 I say don't sweat it. Even if you had a 1/9 you'd still be fine unless you want to go beyond the 69-gr bullets, which most don't because they're typically much more expensive than the lighter M855 and M193 loads.
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    VIP Member Array pittypat21's Avatar
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    Quote Originally Posted by Christopher67 View Post
    I had a local Cabelas employee tell me that shooting a 50-55gr bullet out of a 1/7 twist wouldn't hold together once it left the barrel, not to mention he was rather rude & would elevate his voice while talking to me lol.
    HA!

    I have a 1/7 on my 20"bbl. I have nothing but 55gr rounds right now. At 100 yards I had a nice little group of 3 rounds in about 1-1.25" using irons.

    At a longer range, probably using a 62-75gr bullet would be even better, but believe me when I say that a 55gr will be just fine. Unless you're going to be doing known-distance competitions at 2, 3, 5, or 600 yards, 55gr will be just fine.
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    1:7 "Shoots heavier bullets better" is only partially correct. With the advent of the steel core penetrator 62 grain bullet (green tip), the bullet was significantly longer (same applies to non-tox all copper bullets) than a normal bullet because the steel core being lessor density with weight to the front. The 1:9 didn't stabilize M855 steel penetrator well beyond 250-300 yards.

    Normal 55 to 75 grain bullets stabilize fine out of 1:9 out to 500 yards, beyond that some bullets do better than others.

    1:7 is adequate on 55 grain bullets but doesn't seem to do as well as 1:9 or even 1:12.

    As a rule of thumb (remember it is gun and load dependent...what shoots in mine might not shoot in yours)

    1:12 = 55gr or less

    1:9 = 50 to 75 grain

    1:8 = 55 to 75 or greater with a wide variety of bullets

    1:7 = 55 to 75 grain (or more) and steel core and non-tox all copper bullets


    Some reading:

    http://www.thetruthaboutguns.com/201...or-your-ar-15/

    http://www.travel-golf.org/rifling_t...t_accuracy.htm
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    Member Array Christopher67's Avatar
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    Awesome, thanks for the replies everyone.

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    Quote Originally Posted by Christopher67 View Post
    I had a local Cabelas employee tell me that shooting a 50-55gr bullet out of a 1/7 twist wouldn't hold together once it left the barrel, not to mention he was rather rude & would elevate his voice while talking to me lol.
    Seems that not only was he rude and loud, but he was full of bovine excrement too!
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    Member Array Christopher67's Avatar
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    Quote Originally Posted by Chorizo View Post
    Seems that not only was he rude and loud, but he was full of bovine excrement too!

    Agreed..


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    Here is what an 18" 1:8 twist barrel does with a 55 gr V-max bullet (factory reloads!)



    typical first shot if I do my part



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