AR-15 barrel twist rate

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kawtech87

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Hello, im new to THR but ive read alot of post as a guest and always found them helpfull. So now i decided to join so i can ask pointed questions and learn more about specifics. Like this one, ive shot several ARs and have a Ruger SR-556. All have had a 1/9 twist barrel. I was wondering is there really any difference accuracy wise between a 1/7, 1/8, and 1/9 twist rate? I normally use 55gr ammo and hardly ever shoot over 200 yards, so would buying an upper that has a barrel with a different twist really help my groups? any info would be greatly appreciated. Thanks.
 
Hello, im new to THR but ive read alot of post as a guest and always found them helpfull. So now i decided to join so i can ask pointed questions and learn more about specifics. Like this one, ive shot several ARs and have a Ruger SR-556. All have had a 1/9 twist barrel. I was wondering is there really any difference accuracy wise between a 1/7, 1/8, and 1/9 twist rate? I normally use 55gr ammo and hardly ever shoot over 200 yards, so would buying an upper that has a barrel with a different twist really help my groups? any info would be greatly appreciated. Thanks.
 
Thanks mc223. But honestly that stability calculator just made me confused. Im not a reloader and dont know alot of the indepth info it asks for. Im a recreational shooter and have been wanting to try my hand at some 3 gun matches. I guess what i shouldve asked is if anyone has experinance with different twist rates in match settings, and what shoots match ammo the best? i know i dont want to use my Ruger (atleast not the upper) its to heavy to run around with.
 
For 55gr, there will be no improvement in accuracy. If you start loading longer, heavier bullets, the faster twist will start to come into play. You're fine.
 
Twist rate won't make your gun more accurate. It will only change the weight of the bullet you use. (I'll generalize) Most Varmint shooter like light 40gr bullets so they choose twist rates like 1x12. Long range target shooters like heavy bullets like 80gr so they use 1x7. Most like to use something in between like a 1x9 which can shoot many bullets fairly well. I had a 1x9 and I shot 52gr mostly but also 55's and 69's.

You must find the best round for your specific barrel. For 1x9 try 52, 55, 69, and see which ones works best.
 
Accuracy is not dependent on twist. There are really no hard and fast rules other than the slowest twist that will adequately spin stabilize the desired projectile.
Since you don't reload you are at the mercy of the factory type loadings and extensive testing can get expensive. However I think that unless you just have a ton of cash laying around that you can use for an upper. Find Ammo that works as near to what you want with what you have. I have a couple 1 in 9 barrels that shoot very well from 50g to 75g bullets. I also have a 1 in 8 that is not so hot with 55g and less and yet another 1 in 8 that just loves the little 52s. Your results will vary and sometimes from ammo batch to the next

If you have your heart set on a new upper, I would recommend you call John Holliger at White Oak Armament and explane what you want to do and your end use. You would be very happy with one of Johns uppers and his recommended ammo.

My feeling is that unless you are shooting 80g bullets exclusively there is no need for the 1 in 7.

If you only want to shoot the cheap 55s, what you have is fine. Either upgrade Optics, ammo, or work on technique to improve groupings.
 
Ok so heavy bullets need a faster twist and lighter ones a slower twist. But accuracy will be the same for either as long as its the appropriate grain for the twist. I get it. I would love to play around with more types of ammo and different grian bullets, but my ammo budget keeps me limited to whatever the gun shop has on sale in bulk, normally winchester 55gr. I can normally keep between a 2 and 3 inch group with it. Ill start playing with it as soon as the weather figures out its spring and starts to warm up. Thanks alot for the info.
 
It not actually the weight of the bullet it is the length of the bullet. Heavier bullets tend to be longer. Longer bullets need faster twist to stabalize in flight.

A 2 to 3 in group is a dead deer where I come from. I shake that much when it gets cold.
 
Lighter bullets don't "need" a slower twist but they can be shot with a slower twist. Twist rate only determines the longest bullet that the barrel can stabilize. You might lose some accuracy shooting Winchester 55gn FMJs from a fast twist barrel, but only because the fast twist exacerbates the effect of the Winchester bullets being horribly balanced. If you look at the base of the Win projectiles, they are very inconsistent. Spinning that faster than necessary causes the bullet to wobble excessively.

Bottom line, if you're shooting ammo that 1) is easily available and 2) loads from the magazine, a 1:9 twist is fine.
 
mc223. Thats true here too but i cant hunt with my AR here. Indiana only allows rifles in pistol calibers. Nothing high powered. Thats what my Marlin 1894 in 44mag is for. By the way, no i dont have a ton of cash right now. Im a motorcycle tech by trade and winter in indiana SUCKS for me! I only have about six months to make all my money for the year then i spend the winter blowing it on new toys and food. The upper ive been looking at is an RRA elite comp for about $800.00 and my favorite toy store has it on the shelf. whats the base price on one that mr. Holliger builds and whats the approximate wait time?
 
So a faster twist can cause premature barrel wear? Ive never heard that. Is that just non chrome lined barrels or does it happen on chrome barrels too?
 
Ive heard it but never personally seen it. Kindof sounds likely with the bullet seeing a lot of spin acceleration in a very short distance.


Holligers products are what the winners use. Each is built to your spec. And yeah the pricing is good.
He uses Kreiger barrels on the high side and Wilson(not Wilson Combat) barrels to stay on the cheaper side. All of the Wilson's that I have are very good shooters within the preferred ammo for each.
 
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With all due respect to Mr. Quinn there just doesn't seem to be very many products that he don't like. I have all but abandoned Gunblast as a point of reference because of what seems to be very biased revues.

From Gunblast
Winchester USA 55 FMJ velocity 2858 group 1.75
Click to expand...
Click to expand...
So kawtech87 if you adjust your grip and hold your mouth just right you should get a inch and three quarter group. Of course this could be really crappy and was fired at 50yds which would make your groups at 100 bout right.

Another point is the piston op system does tend to put some accuracy robbing stress on the barrel.
 
Madcrate hit the nail on the head. Great chart!

Burning up an AR barrel will take somewhere in the neighborhood of 10,000 plus rounds, maybe more on a chrome lined barrel. I run an unlined 1:7 barrel and have no issues. I like 1:7 as it gives me the best selection of bullets that it can easily stabilize. It will not shoot the very light varmint bullets that well, but I'd rather use 55 grain bullets anyway, or heavier.
 
Keep in mind that it isn't just precision shooters who tend to favor 1:7 twist. If you plan on using your AR for defensive purposes, some of the best defensive ammo uses 70+ grain bullets.
 
BushyGuy said:
1/7 burns up the barrel faster then a 1/9 twist rate, 1/8 is in between.

i am happy with 1/9 twist rate but i would like a 1/8 not a 1/7 thats too fast!
Click to expand...

So a copper jacket over a lead bullet will wear a hardened steel barrel...that's a good one. If accelerated too hard in a super fast twist barrel (which 1:7 really isn't) the normal result is the bullet skipping across the rifling, getting some of the jacket shaved off in the process, before it starts tracking. This has essentially zero effect on barrel wear.

It is a myth that faster twist barrels don't shoot lighter bullets well. Yes bullet wobble is accentuated by a faster twist, but a bullet suffering from poor balance isn't exactly the gilt edge of accuracy to begin with. You might be talking the difference between a 3MOA round and a 3.5MOA round when going from a 1:9 to a 1:7. With well made bullets the difference is non-existent.

The only other issue worthy of consideration is that of bullet breakup. This is a factor of bullet design and construction, not bullet weight. There have been some very lightly constructed bullets produced intended for varmint shooting varmints with lower velocity cartridges (22 Hornet, .221 Fireball, etc...). Some of these bullets have a propensity to essentially disintegrate if pushed too fast or spun too fast. These bullets are usually easy to pick out in a loading manual either becuase they are specifically highlighted in the text or the load velocities listed are slower than the loads for heavier bullets.

The only other issue that even exists is that of a bullet not tracking its flight arc with its spin axis because of a high rate of spin. This has been shown to be less than a degree of variation at normal trajectories and will have no effect on accuracy over normal ranges (out to 1000yds).
 
NAVY SEABEE 303 said:
How will barrel length effect accuracy? For example on my AR I have a long (26") barrel with a 1in9 twist. I haven't tried to take her out very far yet all I do know is it makes sub moa.
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Once again, no effect on accuracy. With issue rifles (no optics) the M16 is easier to shoot well than the M4 sized weapon becuase of an increase in sight radius and the increase in available aiming precision that allows. Add optics to the equation and they are equals.

What the extra barrel length does give you in an increase in velocity and a corresponding increase in max lethal range. With most ammo the difference between a 16" and 20" barrel is about 200fps. Beyond 20" the gain per inch is less because of the limited powder capacity of the .223/5.56 case.
 
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