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LeftyTwoGuns
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Posted: 7/31/2009 4:47:28 PM
What is the best twist for a 16" barrel that shoots mostly 55gr... a 7" twist or a 9" twist?
fulautotank
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Posted: 7/31/2009 4:52:20 PM
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.
bob332
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Posted: 7/31/2009 4:54:32 PM

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?
survivorman
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Posted: 7/31/2009 4:54:42 PM
1/7 will shoot the 55 just fine. Stick with the 1/7 you will have a greater selection with your ammo
rain_man
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Posted: 7/31/2009 5:35:43 PM
1:7
better selection of ammo.....
kcr121
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Posted: 7/31/2009 5:36:19 PM

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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fulautotank
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Posted: 7/31/2009 5:44:03 PM
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

fulautotank
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Posted: 7/31/2009 5:55:36 PM
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
kcr121
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Posted: 7/31/2009 5:55:48 PM

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?

Semper Fi
SubEclipse
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Posted: 7/31/2009 5:56:16 PM
[Last Edit: 7/31/2009 5:58:16 PM by SubEclipse]
...
SubEclipse
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Posted: 7/31/2009 5:57:49 PM
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.
kcr121
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Posted: 7/31/2009 6:00:45 PM

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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bob332
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Posted: 7/31/2009 8:01:01 PM

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)
tdowell
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Posted: 8/1/2009 2:53:10 AM
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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bob332
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Posted: 8/1/2009 5:18:13 AM
[Last Edit: 8/1/2009 5:19:38 AM 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?

mrraley
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Posted: 8/1/2009 5:41:35 AM
Getting into a Twist about your Twist?!


Anyone that spends any amount of time at the rifle range or hunting lease will inevitably find himself within earshot of two people discussing barrel twist. Twist as discussed here, refers to the rifling in the barrel of modern rifles making a full 360 degree turn in a given length of inches. As an example, a 1x7 Twist means the rifling makes one 360 degree turn for every seven inches of barrel.

As it pertains to .223 projectiles, several different twists are currently produced. Not all ammo shoots well in all twist ratios. A barrel with a 1x7 Twist tends to be too tight for most lighter, more commonly fired ammunition. Originally designed for the military's use of SS109 (the official NATO name of 5.56mm, or .223), further military testing concluded other twist ratios are actually superior for this steel core bullet. 1x8 Twist is best suited for 69-80 grain bullets. Our Federal .223 69 Grain BTHP Match Gold Medal is some of the best on the market for this twist ratio. 1x9 and 1x10 twist ratios are sort of the "middle of the road" for .223 projectiles, and these are the most common. We suggest our Hornady TAP 55 Grain. On the lighter side of things, a 1x12 boasts excellent accuracy on standard and lighter projectiles in the 40-52 grain range. Older M16 rifles were manufactured with the 1x12 Twist ratio. Our item number ARR-115 offers a conversion upper for your AR that takes less than a minute to install, and the barrel has a desirable 1x12 twist ratio. If you are buying a varmint rifle chambered in .223, chances are it will sport a 1x12 Twist Ratio. Our Federal Premium .223 Remington 40-Gr NBT is perfect for varminting. Last, we have the 1x14 twist ratio. Probably the least accurate ratio unless you are into bullet tumble as opposed to spin unless you are shooting custom loads.
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youngmoney11
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Posted: 8/1/2009 6:24:49 AM
16" barrel 9" twist is usually standard for 55g
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Posted: 8/1/2009 8:55:55 AM
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.
Too tight? You could park a jumbo fucking jet in there!