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1:9, 1:8, or a 1:7?
When it comes to AR-15 barrels…you may be noticing different rifle twists in their specs.
Does it really matter that much?
Will the wrong weight bullet for your twist rate make it fly off into the sunset?
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Bullet Weight Does Not Dictate Barrel Twist
The first thing that needs to be understood is that bullet weight does not directly have anything to do with what rifle twist you should be using in your AR15 barrel chambered in 5.56 NATO or .223 Wylde. Now before some people start pounding their table, and grabbing pitchforks, let me explain. Bullet length is what ultimately dictates your barrel rifling twist. If you do a quick google image search, you will find a few different charts or graphs that specifically show bullet weight and which rifle twist you “need”.
A Cliff Notes History Lesson
In the early years of the AR15’s development, the rifling twist that was adopted was a 1:14 rifle twist. The easiest way to explain what that means is that the rifling makes a complete twist 1 time every 14″. Most loads shot through these barrels were a very short, lightweight bullet in the 40-55 grain category. You can read a more complete history of the M16, but for now, let’s fast forward to the present.
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Capitalism at Its Finest
So why are there multiple rifle twists on the civilian market with the 1:9, 1:8, and the 1:7 as stated before? Short answer: Capitalism.
If you are a red-blooded American, you enjoy the perks of capitalism.
The one drawback of capitalism though is that the market breeds more choices and more decisions. A lot of barrel manufacturers sell all of the top three rifle twists in their barrels, and it can be a little daunting when you are trying to figure out which one to get.
We covered the fact that you need to properly stabilize a bullet, and we have covered a quick history of different rifle twists. Stick with me here, because I am going to make this a very easy decision for you.
A Lot of Bad Info
Out in the unnatural world of the interwebs, you can run into a lot of bad information regarding practically anything. Rifle twist and bullet choice are no different. When it comes to slower rifle twist, i.e. 1:14, 1:12, 1:9, you really shouldn’t be shooting bullet weights over 65 grains or the equivalent length for a 65-grain bullet. It won’t damage your rifle, but you will have very poor accuracy.
Shoot, Switch Ammo, Repeat
I decided to run through a little experiment with multiple loads of .223 Remington and 5.56 NATO. Ten different loads to be exact. And to make this even more scientific, I did it with two different rifles that both have a 1:7 rifle twist. The first rifle that I tested is a home-rolled rifle that utilizes a Radical Barrels, LLC 20″ 416R stainless barrel. Rick Hoffmeyer of Radical Barrels, LLC made it for me, and it’s a fantastic barrel. The optic on this rifle is an ACME Machine 6-24x50mm FFP TR-MOA. For the price, it is hard to beat for a first-focal-plane optic.
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- Hornady 40 Grain V-Max
- Winchester 45 Grain JHP
- Federal 50 Grain JHP (Varming & Predator)
- Remington UMC 50 Grain JHP
- Tul-Ammo 55 grain FMJ (Just for the hell of it.)
- Barnes 55 Grain TSX
- Remington 55 Grain PSP
- Barnes 62 Grain TSX
- IMI 77 Grain OTM Razorcore
- Barnes 85 Grain OTM
Moment of Truth
With ten different loads, all varying from the lightest/shortest to the heaviest/longest projectile that will fit inside the mag well of an AR15, I went about firing 3 round groups with each load at 100 yards to test how well each bullet would do. I fully understand that some purists may be wringing their hands in the air because I did not do 5 shot groups. I get it. When I really test accuracy for a specific load, I fire 5-10 round groups to really see its potential. The reality of the situation is that I have kids to feed, and a wife that will literally stab me to death in my sleep if I drain my bank account for ammo. She showed me the knife…Best Budget Survival Knife
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Decisions, decisions…
So its time to pay the piper, and make a decision on the rifling twist that will best suit your needs as a shooter. My vote is a 1:7, hands down. With a 1:7 rifle twist, shooting quality ammo, you can go as light as you would like with commercially available ammunition. A case could be made that “over-stabilization” can bring about issues at extended ranges, but why would you honestly shoot a 40-grain projectile past 300 yards? If you are actually trying for accuracy at extended ranges of 300-700 yards, a 69-85 grain bullet is much better suited for the task at hand. For up-close shooting drills, or within 300 yards, bulk 55 grain M193 will do just fine as well out of a quality barrel when you are on a budget.Best 5.56 XM193 55 gr
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Prices accurate at time of writing
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44 Leave a Reply
I recently bought a Springfield Armory Saint Victor in 5.56 NATO. It is a 16" 1:8 twist barrel. I put an Aimpoint PRO on it and went to the range. At 25 yards it was fine, but at 50 yards, the 3-shot group was abysmal. I was shooting Winchester M193 55 grain loads. At 50 yards, I was getting 4" plus groups. If it were a combat situation, I suppose that would suffice? But I want to do better. MUCH better. I found your chart, and so I think I`m going to try something, per your chart, in the 69 to 85 grain bullet range. I was hoping to shoot 55 grain because I perceive those to be more available. I wonder, do I as well as going to a heavier bullet need to get a more premium brand, like Black Hills, Federal Gold Match, Hornady, etc.? I don`t have the money, nor the patience to buy numerous different brands and weights to shoot, but I`d still like to make this rifle shoot much better at longer ranges. What would you recommend?
My subjective, non-scientific observation is that 80% of the 5.56 ammunition manufactured and sold on the civilian market is M193. Assuming my observation is somewhere close to the truth, why do 90% of AR15s sold on the civilian market have 1:7 barrels? Since I don't reload and have no interest in über accuracy, I'd be perfectly happy with a 1:12 barrel.
I’m trying the Speer Gold Dot 64 grain in a 1-9 twist barrel. Speer did both a 62 and 64 grain. I know the 62 grain is good for at least 100 yards with the 1-9 twist but I’m going to see if the two grains difference with that barrel is a significant factor or not?
Yo, with a slower twist rate you do not NEED to use heavier/longer bullets! When did that myth start? Longer bullet will fragment just as a 55gr out of a 20" barrel would, welcome home!
You want a bullet that is stabilized enough for cold weather and distance for a 55 gr M193, so 1:12. Want to use M855? Then go with a 1:8 or 1:9.
Top notch article, very useful information. Appreciate your service.
Semper Fi devil dog, good article.
I once had a Colt HBAR 1:7 twist. Iwas handloading 69g HPBT for High Power matches. One load velocity was high enough that the centrifugal force disintegrated the bullets shortly after they exited the barrel! Backed that load down a bit and it made really tight groups
Hi Mark, fascinating comment.
I suspect though that it isn't just rotational energy that disintegrated the bullets. In order to provide a twist, the barrel is tugging (backwards) on the bullet (converting forward energy to rotational energy). That tug causes a sheer within the bullet - the bullet is moving forward but the outer wall of the bullet has drag on it.
So my expectation is that it is the combined mechanism that tears apart your bullet. The bigger the push from the powder, the bigger both forces are. Maybe the outside shear starts the ripping, then it blows apart when it leaves the barrel.
All speculation of course.
Tight groups at what distance?
Shooting at 100 yds, I was getting 1 to 1-1/2” groups, from sandbags, using a 3x9 scope mounted on the handle. Sold it to a dealer when CA put it on the AW registry list.
Thank you for verifying the information on the chart, it helps me to know that what you saw corresponded exactly with that information.
Was building a rifle and decided to go with a 1:9 Ballistic Advantage 16 inch 5.56. All of my ammo is 55 to 62 grain, not sure how often I would get my hands on anything much longer/heavier. With the price of ammo these days and availability of not just barrels but ammo as well, I thought it was a safe bet. Great article with tons of information.
Two weeks ago I bought the Colt, no longer called the LE 6920, but is now the CR 6920. Has the 1:7 twist rate and I shoot both the factory 55gr and 65gr ammo with 3/4" groups from 100 yards. Will be reloading soon with the 55gr FMJ Boat Tail to try them out, and then will be casting my .225 lead bullets if Lee ever gets back on production for the 2 or 6 cavity molds
That bullet weight with that twist rate doesn`t align with that chart...
I have a DPMS, with 1:9 twist. I don’t reload for it, so us factory ammo. Norma Tac 223 55 gr will consistently shot .6 inch groups at 100 yards. Unfortunately, they stopped making it! Damn!
I am looking at buying a PWS MK111 MOD2 PISTOL in 223Wylde rifled in a 1:8 twist rate. Can someone tell me why it has a 1:8 versus a 1:7 based on everything I have been reading the last several days about twist rates??? From all the hours of reading I have done, clearly 1:7 seems like the correct twist rate for this rifle. But now I am confused and don't know if I should make the purchase. Please help a friend...
I'm waiting for my 11.85 PWS pistol as we speak. Perhaps the rifling PWS chose is because of the availability of ammo for that twist rate. I see much more lighter grain ammo then the 80gr plus ammo.
One thing that's obvious here is that if you switch ammo you want to know where it's going to go. The 45 gr Winchesters had good group size from both rifles but way different POI! Don't know what you were sighted in with, both liked 50 gr Federal for POI and group, which some would say are too light for that twist. I have an old Mauser 98 with a 30/06 barrel on it, at 100 yards I get good groups with 150 and 180, just a foot of difference in the impact point, not good to switch ammo on that one.
I totally agree with what your saying. I believe it's more find what your barrel likes and groups well. I have a Ruger 556 mpr 1 in 8 twist 18 inch barrel 5R rifling. It groups high and left at 100 yds with fed American eagle 55 grain and groups between 1 1/2 and 2 moa from a Caldwell steady rest . But poi is center bullseye with Hornady frontier 55 fmj m193 style ammo groups about 1 to 1 1/2 moa. Groups ok maybe 1 1/2 with imi 77grain but loves magtech 77 gr groups magtech almost same poi as Hornady 55. Magtech grouped from .69 moa to 1 moa according to range buddy app. It really loves buffalo bore 77 gr sub moa. But not so much buffalo bore 69 gr. Which I can't afford 1.35 per round anyway . So you just have to try different ammo weight name brands etc..
ok tons of food for thought, around my place my enemy list is, mice, rats, racoons, possums, coyotes, and any other thing that gets my chicken eggs, my 1999 1/10 mini 14 has for years and still is flawless, but most of the people i shoot with have all went AR-15's, and to shoot for a day you must go heavy barrel , my new toy was paid for several months ago and still back ordered, to late for the short version, i've went with a left handed stag 24 inch barrel 1/8 twist, so unless i have misunderstood, i should be good 62 thru 77, plus the satisfaction of shutting up the mouthy at 600 to 700 yards,
Great article Marine, I got a 1/9 in my Ruger SR556 and a 1/8 in my Aero Precision. Use only 62-69 grainers in both. The 1/8 is a sub MOA all day long while the 1/9 is MOA+. Shoot PPU and Gold Medal Match 69 gr the most. Both loads are .223 Rem and the 62 gr are M855 Green tipped 5.56x45mm. The 1/8 using the GMM is a 500-700 yard shooter while the 1/9 can only reliably reach 300+ yards. Contacting Ruger for a 1/7 for the SR556. It’s a top shelf piston gun and why it came with the 1/9, I’ll never know. Also, I’ve heard stories of 35-40 gr bullets from a 1/7 rotating to disentigration. Sounds like a fable as I’ve never witnessed it. I can’t picture a projectile literally coming apart due to over stabilization. Anything’s possible, I guess. Semper Fi. Thanks
LOVE the article. There is one big mistake in the description of the aurhor. One a Marine always a Marine. There is no prior service associated with this branch of our military. Semper fidelis
Ooh rah!
I read through this article pretty quick. Did I miss or did you not mention the length of the barrel is a major determining factor along with twist rate?
The first M16's had 20+ inch barrels.
Shorter barrels and longer bullets was the reason for faster twist rates.
Actually barrel length only affects velocity which will affect poi down range it shouldn't affect what twist rate other the getting higher velocity from a shorter barrel for terminal performance at a longer range I do believe the 1 in 7 twist came about in the military to better stabilize the longer 62 gr tracer rounds
Very good read, I take it from the graph at the top a 1-8 is more or less the "Jack of all" seeing it will work well with most ammo. The one think I did see in the photo's is that the point of impact changes with each load. Find the one you tube likes and stick with it.
I was actually expecting a larger point of impact change from each type of bullet, but there was a definite change. And that is to be expected. But accuracy wise, most of the loads were more than reasonable in accuracy in my opinion. And a 1:8 is a solid choice, but I still prefer the 1:7.
Good article, very informative
Thank you very much Richard!
Thank you for this article, Ken. I am about to buy my first AR. I have taken my pick and there was only one concern that I had regarding the soon-to-be-mine rifle: the 1:7 twist in a 16,5 inch barrel that comes with it. Obviously I was afraid that the standard 55grain bullets (or lighter) would not do their job, but after reading this I feel relief:-) I'm going for shopping:-) Greetings from Poland to you and the whole PPT team!
Thank you for reading!
How about a 24” barrel with a 1:8 twist for AR15? I hope you can add this to your next article.
Barrel length doesn't have an impact on twist rate selection, a 16" barrel and a 24" barrel will like the same twist rate for the same bullets. Barrel length will impact velocity, to a point.
Too bad you weren't able to test barrels in 1:8 and 1:9...sounds like the content for a follow-up article.
For sure!
Absolutely. We now have the 1:7 perspective, but how about those of us with 1:8 and 1:9 barrels? I think we need another, expanded test. BTW, good read. Thanks.
You need to mention the barrel “burn out” factor for the 1:7 if you intend to shoot the rifle a lot. I don’t know what the number of rounds might be but it WILL happen faster and you’ll start getting bigger groups. For that reason 1:8 is the ideal twist rate IMO.
This is really not a factor to consider imo. Just get the best 1:7 or 1:8 you can afford, the 1:9 twist of the MP Sport 2 is fine for many AR owners as well. if it is a well built 1:8 it will be more accurate than you'll ever be. And if it is a good 1:7, unless you shoot ten of thousands rds per year you will not have to worry about replacing it for a long time.
Very informative, well written. Enjoyed reading it.
Thank you Ray!
FWIW, I have a Ruger M77 .243 built in 1975. It has a 24" barrel and 1 in 9 twist. This is kind of an apples to oranges comparison with ARs tested above.
Very accurate rifle when firing 100 grain lead. But being in California, I can only hunt with non-lead ammunition. I tested both factory Barnes 80 grain and factory Hornady 80 grain. Both plastic tip. The rifle went from 1.5 - 2.0 MOA to 2.5 - 3.5 MOA using both the Barnes and Hornady copper 80 grain.
A friend hand-loaded some Barnes 85 grain hollow point copper and some Nossler 90 grain copper with plastic tip. The rifle shot the Barnes 85 grain very well (comparable to the 100 grain lead.) But the Nossler did the same as the 80 grain, shooting big groups.
So I'm not sure if I'm fighting weight versus twist, or if I just have a rifle that doesn't like plastic-tipped bullets. Or maybe I'm not that good a shot.
Either way, I'm probably going to have to relegate this rifle to coyotes because a .243 is on the brink of being too small for deer to begin with. We're in open country where 200 yds is probably the average distance to target. My nephew thinks my answer is a .25-06 or a .270.
That sucks the groups have opened so much, but it's a good time to get a new rifle! I would highly recommend a Tikka T3x in .270. That is my go-to deer rifle and I have to say I am completely in love with it. There is also some really good CA legal hunting loads for it.
Paul, I shoot a Browning A-bolt in .270 for California deer and boar. It has never let me down. I think the 270 would be a good next rifle for your deer needs. Happy hunting.
So my budget friendly DPMS, came with a 1:9 twist barrel. Being new the AR and not knowing much yet. What do I need to keep in mind when buying ammo?
1:9 is going to like lighter ammo, anything from 35gr to 62gr will stabilize well and give you the best groups. However, anything heavier than that is going to start to suffer. How much that actually matters to you depends on what you want to use your rifle for. If this is for plinking, well the cheapest ammo by far is almost always 55gr so you're good to go!
But if you want to try to hunt game larger than a coyote with it or take it to some long-range precision shooting, you're going to see groups open up or rounds keyhole if you try to use heavy ammo for it.