# AR how much twist in the barrel?



## budgetprepp-n (Apr 7, 2013)

If you are looking at an AR that is just for shtf and you know you may be feeding it any ammo
that you could get your hands on. Different loads and different weights.

What twist barrel would be the best for all round use?


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## SDF880 (Mar 28, 2013)

1 / 8 ?


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## HuntingHawk (Dec 16, 2012)

Twist is in relation to the weight ammo you are going to use.


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## Smitty901 (Nov 16, 2012)

20 inch barrel firing the 55gr 1 in 12
16 inch with 62 grain 1 in 7
The 1 in 9 is more for punching holes in paper
The 1 in 8 was one of those ideas to split the difference.
There is a reason most 16 inch are 1 in 7.

EDIT: Of course this is general when you get into custom loads non standard rounds things do change. The AR was never designed to be a sniper rifle it was to hit stop humans at a wide range fast. However by playing with them some have made pretty good tack drivers out of them.


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## Slippy (Nov 14, 2013)

Smitty901 said:


> 20 inch barrel firing the 55gr 1 in 12
> 16 inch with 62 grain 1 in 7
> The 1 in 9 is more for punching holes in paper
> The 1 in 8 was one of those ideas to split the difference.
> There is a reason most 16 inch are 1 in 7.


Thanks Smitty, as always I appreciate your insight Sir.

But, I still don't want to get shot by any of them! 

A while back I did an experiment. I am no marksmen by any means, just a smart ass guy with a range and some firearms that may or may not have been lost at sea...so take this with a grain of salt (55 or 62 grains, doesn't matter to me  )

Shooting from a bench at 100 yards with 3 different rifles; SigSauer M400 16" 1-7, Colt LE6920 16" 1-7 and Century Arms C15A1 20" 1-9. I used both 55 g and 62 g 5.56 Federal Ammo. The Sig and the Colt performed about 1" MOA better using the 62g ammo then the Century. But the Century performed equal MOA to the Sig and Colt using the 55 gr ammo. I forget exactly how many rounds I shot with each but it was probably less than 20 each.

What did I learn? That I can punch holes in paper with relatively the same accuracy with 3 firearms of similar but slightly different qualities with similar but slightly different ammo.

I stand by my statement above that I do not want to get shot by any of them! 
Thanks for listening...


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## AquaHull (Jun 10, 2012)

I know I can hit a softball size target 20 times freehand at 50 yards with 55/62/69 gr ammo with my Daniel Defense LW 16" Mid,1:7 of coarse

Farther than 50 yards, I use the scoped 243 or 30/06's


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## Smitty901 (Nov 16, 2012)

The 1 in 9 works well in a 22 inch bolt action .223 for small and medium size critters. It will give you some darn good longer distance shots. There are just so many exceptions to any rule today to many other things come into play. One issue with the M16 20 inch and both the .223 and 5.56 55gr round was it did not produce enough damage sometimes to stop a target fast enough. It did however make some impressive longer shots in trained hands. They tried the 5.56 55gr in the 16 inch and it just did not work out the 62 and 77gr did.
The 62 grains was chosen because it worked well in both the m4 and the SAW 249 and covered a wider range of needs than the 77gr.
You want to read some strange stuff on rifling and twist. Read up on what they did with this one, they also have a 308 version. The rifle is different than what you are use to and the barrel gets even better when a large number of rounds are fired. This is just an example of a world where the rules are always changing. When they add to this a custom loaded boat tail the range is down right scary.

XM2010
Barrel: Made of 416R Stainless Steel. The bore twist is 1-turn-in-11.25 inches [1:285.75 mm] and the rifling is five radial lands and grooves (5-R) with a right-hand (RH) twist. Because of the odd number of lands, none of the lands are 180° apart, i.e. in direct opposition. This results in less bullet deformation, which (at least in theory) produces more consistent point of impact. In 5-R rifling, the "side" of the land is cut at a 65° angle, rather than 90° in conventional rifling. This results in less barrel fouling, and more consistent point of impact, compared to conventional rifling when relatively high numbers of rounds are fired between cleaning, as might be expected in military applications


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## Slippy (Nov 14, 2013)

Smitty,

This may be off topic a bit but I've got some military surplus 5.56 M196 55g tracer rounds. Their accuracy is horrible and I've only fired them in my 20" 1-9 barrel AR15. Are tracer rounds inaccurate as a whole?


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## Smitty901 (Nov 16, 2012)

Slippy said:


> Smitty,
> 
> This may be off topic a bit but I've got some military surplus 5.56 M196 55g tracer rounds. Their accuracy is horrible and I've only fired them in my 20" 1-9 barrel AR15. Are tracer rounds inaccurate as a whole?


 No generally, but the tracer does not really follow the round very well in many cases. Tracers tend to throw a shooter off a bit. The 55gr round is meant for the 20 inch 1 in 12 that is where it shins the best. When the change o the M4 came we used the 55gr at the range but it was not to be used for qualification. In the shorter barrel and 1 in 7 the 55gr had a wide 3 shot placement on zero range.
Not to say you could not still hit 40 out of 40 on a 50 to 450 Meter range (train shooter) . Average shooter 30-38 hit in allowed time.


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## Slippy (Nov 14, 2013)

Smitty901 said:


> No generally, but the tracer does not really follow the round very well in many cases. Tracers tend to throw a shooter off a bit. The 55gr round is meant for the 20 inch 1 in 12 that is where it shins the best. When the change o the M4 came we used the 55gr at the range but it was not to be used for qualification. In the shorter barrel and 1 in 7 the 55gr had a wide 3 shot placement on zero range.
> Not to say you could not still hit 40 out of 40 on a 50 to 450 Meter range (train shooter) . Average shooter 30-38 hit in allowed time.


Makes sense.


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## Smitty901 (Nov 16, 2012)

Slippy said:


> Makes sense.


 The burn is in the rear of the cartage but does separate at times also the way people eyes work it mess with them.
If you get a chance some time load 3 mags each with 3 rounds shoot those at 3 different zero target with 55gr. Then do the same with 62 gr repeat this 3 times and measure you group sizes. Then for fun do the same thing at 100-150 meters . Watch how the groups become more alike .


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## 8301 (Nov 29, 2014)

I did a little reading on this topic last month and with the shorter 16-18" barrels most AR carbines use the 55 gn weight works well at the slower twists like a 1/12 with the shorter barrels. The 55 gn may loose a tad of accuracy at a faster twist rate such as a 1/7 but the difference was tiny.

Heavier rounds like the 77 gn lost a bit of a accuracy in a short slower twist barrel and do best with a faster 1/7 twist. Any twist between 1/7 and 1/12 will work well with the 5.56 and .223, after that it's a matter of fine tuning your ammunition and bullet weight. Personally I think a 1/9 or 1/8 would be optimal giving you the best flexibility in ammunition performance.

From what I've read some manufactures are going to a progressive twist starting at 1/10 in the rifle's throat and tightening to 1/8 at the muzzle end. The S&W M&P 15 Sport does this and claims a 1/9 twist since that is the average barrel twist.

Keep in mind that this tiny bullet does its damage through speed and with a shorter barrel you will loose a bit of muzzle energy.


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## AquaHull (Jun 10, 2012)

Flame ON

:: Ammo Oracle

:: Ammo Oracle

:: Ammo Oracle

:: Ammo Oracle

:: Ammo Oracle

https://www.ar15.com/archive/topic.html?b=3&f=118&t=512635


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## 8301 (Nov 29, 2014)

AquaHull said:


> Flame ON
> 
> :: Ammo Oracle
> 
> ...


Good articles and generally agree with other information I had found.


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## bigwheel (Sep 22, 2014)

Great info folks. Those rifling twist rates can be confusing. Seem to recall the faithful old 6mm problems were caused by too slow of twist which did not work well with longer or maybe heavier bullets. So as the guy said when you got a dog who wont hunt..you give the dog a new name. It got a faster twist rate and new name..aka .243.


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## Hemi45 (May 5, 2014)

Colt 6920, 16 inch (govt. profile) 1/7
Colt 6720, 20 inch (match HBAR) 1/9

I reckon Colt knows what they're doing and I trust both gun's engineering. That said, if I could have only one, all purpose, barrel it would be a 1/8.


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## SGT E (Feb 25, 2015)

Smitty901 said:


> 20 inch barrel firing the 55gr 1 in 12
> 16 inch with 62 grain 1 in 7
> The 1 in 9 is more for punching holes in paper
> The 1 in 8 was one of those ideas to split the difference.
> ...


I have a Bushmaster Varminter 24 inch barrel over the counter stock / Vortex Viper 6.5 X 20 Scope 1 in 9 twist....On the first target bull below I dialed 4 clicks right...easier to see on white paper and thats a .278 group at 100 yards with 69 grain Nosler custom Competition match bullets HPBT. Second 1 inch target dot is same rifle and scope dialed dead on at 100 yards...10 shots of 50 grain Nosler BT Varmint It may be a paper puncher but it does head shots on prairie dogs and groundhogs at 300 yards consitently! You have to reload your ammo to get this kind of accuraccy every time you shoot otherwise its a 1/2 to 3/4 incher average with store bought ammo. That makes a big difference at 300 to 500 yards though! You might call it a paper puncher but a couple thousand dead Prairie dogs and a hundred or so groundhogs would argue with ya!


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## bigwheel (Sep 22, 2014)

Mighty fine shooting. Poor little Prairie Dog friends..sniff sniff. They are just too cute huh? Hey maybe you could see how close to the dog you can get without actually hurting it. That should work.


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## AquaHull (Jun 10, 2012)

Had one that would sun himself on the deck,yes I could tell.It was in Mount Ghetto(Clemens) so a gunshot would have fit in


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## budgetprepp-n (Apr 7, 2013)

Hemi45 said:


> Colt 6920, 16 inch (govt. profile) 1/7
> Colt 6720, 20 inch (match HBAR) 1/9
> 
> I reckon Colt knows what they're doing and I trust both gun's engineering. That said, if I could have only one, all purpose, barrel it would be a 1/8.


My Colt 6920 16 inch 1/7 came with a H bar and full auto bolt carrier right from the factory. - lucked out 
I been shooting the 62GN maybe I'll try something a little heaver just to see


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## James L (Feb 7, 2015)

My barrel is a 1/8....5.56 62 grain seems to be a good/accurate fit for it.


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## stillacitizen2 (Jan 30, 2015)

My two cents (based on much research)...a 1 in 7 twist seems to be the most versatile. Will handle 55 grainers no sweat, spins the heavy ones plenty fast to get them stabilized. All three of my AR's are 1 in 7. If you're going to use it for really lightweight stuff to gain speed, you need a slower twist, like 1 in 12 or it can spin the jackets right off the core.


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## AquaHull (Jun 10, 2012)

stillacitizen2 said:


> My two cents (based on much research)...a 1 in 7 twist seems to be the most versatile. Will handle 55 grainers no sweat, spins the heavy ones plenty fast to get them stabilized. All three of my AR's are 1 in 7. If you're going to use it for really lightweight stuff to gain speed, you need a slower twist, like 1 in 12 or it can spin the jackets right off the core.


Have you spun a bullet acket off it's core?
I'm on the lookout for some 35-40 varmint bullets that I can load hot and shoot them in a 20" 1:7 just to see if I can "spin the jacket off it's core"


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