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Posted: 7/31/2009 11:47:28 AM EST
What is the best twist for a 16" barrel that shoots mostly 55gr... a 7" twist or a 9" twist?
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Posted: 7/31/2009 11:52:20 AM EST
1/9 is great for 55gr, if you will be shooting 69gr or heavier at any time stick with the 1/7.

If you plan one using with a silencer go 1/7 for sure.
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Posted: 7/31/2009 11:54:32 AM EST

Originally Posted By fulautotank:
1/9 is great for 55gr, if you will be shooting 69gr or heavier at any time stick with the 1/7.

If you plan one using with a silencer go 1/7 for sure.

please explain this to me - are you saying 1:9 + 55-69grn + suppressor = not good? why?
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Posted: 7/31/2009 11:54:42 AM EST
1/7 will shoot the 55 just fine. Stick with the 1/7 you will have a greater selection with your ammo
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Posted: 7/31/2009 12:35:43 PM EST
1:7
better selection of ammo.....
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Posted: 7/31/2009 12:36:19 PM EST

Originally Posted By fulautotank:
1/9 is great for 55gr, if you will be shooting 69gr or heavier at any time stick with the 1/7.

If you plan one using with a silencer go 1/7 for sure.

Huh? This is not true. I really wonder where some of this stuff comes from. My guess is gun shop and gun show dealers.
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Posted: 7/31/2009 12:44:03 PM EST
A 1/9 is no problem with 55-69gr even with silencer.

I meant that you have a wider selection of bullet weights and when using a silencer it is better IMO to have the 1/7.
Just my opinion

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Posted: 7/31/2009 12:55:36 PM EST
Originally Posted By bob332:

Originally Posted By fulautotank:
1/9 is great for 55gr, if you will be shooting 69gr or heavier at any time stick with the 1/7.

If you plan one using with a silencer go 1/7 for sure.

please explain this to me - are you saying 1:9 + 55-69grn + suppressor = not good? why?


Not a problem at all, I would just recommend the 1/7
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Posted: 7/31/2009 12:55:48 PM EST

Originally Posted By fulautotank:
A 1/9 is no problem with 55-69gr even with silencer.

I meant that you have a wider selection of bullet weights and when using a silencer it is better IMO to have the 1/7.
Just my opinion


Again, where does this come from?

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Posted: 7/31/2009 12:56:16 PM EST
[Last Edit: 7/31/2009 12:58:16 PM EST by SubEclipse]
...
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Posted: 7/31/2009 12:57:49 PM EST
I get 1.5 MOA shooting 55gr out of my 16" 1:7... You would get better results with a 1:9, but then the heavier loads aren't an option... I like 1:7 personally.
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Posted: 7/31/2009 1:00:45 PM EST

Originally Posted By fulautotank:
Originally Posted By bob332:

Originally Posted By fulautotank:
1/9 is great for 55gr, if you will be shooting 69gr or heavier at any time stick with the 1/7.

If you plan one using with a silencer go 1/7 for sure.

please explain this to me - are you saying 1:9 + 55-69grn + suppressor = not good? why?


Not a problem at all, I would just recommend the 1/7


See, this I agree with. Given identical profile barrels from the same manufacturer for the same price, I'd always recommend the 1/7 over the 1/9. But would I get rid of an AR because it had a 1/9 barrel? Hell no. That'd be like kicking Angelina Jolie out of bed because her lips aren't naturally that perfect.

To the OP, if you plan on shooting mostly 55 grain ammo, you won't go wrong with either. All of my ARs are 1/7 and shoot any ammo from 52 grains and up with more than acceptable accuracy. The only reason I say 52 grains and up is because I haven't tried them with anything lighter than 52 grains. You'll be fine with the 1/9 too, especially if it's more easily obtainable.
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Posted: 7/31/2009 3:01:01 PM EST

Originally Posted By SubEclipse:
I get 1.5 MOA shooting 55gr out of my 16" 1:7... You would get better results with a 1:9, but then the heavier loads aren't an option... I like 1:7 personally.

not necessarily. i have read many reports where a 1:7 does best w/ 52grn bullets when worked up and hand loaded. some 1:9 do best w/ 69 - some 1:9s will do 75grns just fine because of small differences in manf and true twist rates. if you read around you will see that generalizations will say 55-69 in 1:9 and 55-80 in 1:7 but these are generalizations and not concrete answers.

there are so many variables unless you handload you will really never know what your setup is capable of, but this would be more bench shooting where we would be talking sub-moa and even less in differences. read some of the member's molon posts - lots of info regarind many different loads from long barreled target ars w/ custom brls to colt m4s to noveskes and many in between w/ bullet weights all over the spectrum and brl twist from 1:9, 1:8, 1:7.7, 1:7....not sure if has a 1:6.5 brl for the 90-100grn stuff as of yet but they are pretty rare atm.

remember though, that surplus ammo is like 3-5moa ammo anyway and most match ammo is 1-2 at best w/ handloads going sub-moa (10shot groups, not 3 or 5)
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Posted: 7/31/2009 9:53:10 PM EST
Originally Posted By survivorman:
1/7 will shoot the 55 just fine. Stick with the 1/7 you will have a greater selection with your ammo


Not necessarily true, you can't shoot anything below a 55gr reliably with a 1/7, if you shoot a 50gr JHP, or a 40gr ballistic tip, they can disintegrate when fired from a 1/7 because they are over rotated. 1/7 is a VERY tight spin, the only centerfire rifle that uses it or anything close is the AR. Most Use a 1/10, 1/12 or 1/14. The 1/7 was made for sniping with 20" barreled AR's and will stabilize heavier rounds but is only necessary if you plan on shooting 77gr or bigger, if you are, you'll probably want a match barrel anyway.
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Posted: 8/1/2009 12:18:13 AM EST
[Last Edit: 8/1/2009 12:19:38 AM EST by bob332]

Originally Posted By tdowell:
Originally Posted By survivorman:
1/7 will shoot the 55 just fine. Stick with the 1/7 you will have a greater selection with your ammo


Not necessarily true, you can't shoot anything below a 55gr reliably with a 1/7, if you shoot a 50gr JHP, or a 40gr ballistic tip, they can disintegrate when fired from a 1/7 because they are over rotated. 1/7 is a VERY tight spin, the only centerfire rifle that uses it or anything close is the AR. Most Use a 1/10, 1/12 or 1/14. The 1/7 was made for sniping with 20" barreled AR's and will stabilize heavier rounds but is only necessary if you plan on shooting 77gr or bigger, if you are, you'll probably want a match barrel anyway.

in less than 5mins i have found that savage, tikka and sako all make HUNTING BOLT ACTIONS in 1:7 & 1:8 223 rifles. many people shoot lighter than 55grn out of 1:7s all the time. you should look at the real reason for the 1:7 rifling - look in the ammo oracle.... as time has progressed the long distance shooters like it for their hevier bullets but that wasn't the original reason for it. when was the last time you saw a 1:14 in 223 and what year was the rifle?

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Posted: 8/1/2009 12:41:35 AM EST
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Posted: 8/1/2009 1:24:49 AM EST
16" barrel 9" twist is usually standard for 55g
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Posted: 8/1/2009 3:55:55 AM EST
I shoot xm193 out of both 1/7 and 1/9, not that the 1/7 is inaccurate but there is a noticeable increase in accuracy out of the 1/9 6721 vs. the 1/7 6520.
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