Many of you that are gun geeks understand the basics of rifling can skip this article. This is for the average gun enthusiasts and newbies that enjoy shooting and want a little more understanding of how a barrel twist rate can affect accuracy.
So does barrel twist rate affect accuracy on an AR15?
The short technical answer is that barrel twist starts the bullet spinning at a given rate to stabilize the bullet.
The rate has to be constant for the utmost accuracy.
On the opposite end of the spectrum – Decreasing the twist rate will almost certainly result in a dramatic decrease in accuracy.
Another factor is can the wrong weight of the bullet for your twist rate make it fly off into the sunset? It does matter.
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 – if its an AR15 barrel chambered in 5.56 NATO.
Lets explain a little further.
The bullet length is what dictates your barrel rifling twist.
A general rule of thumb with weight, is that the longer a bullet is, the heavier it becomes.
Newer types of bullets usually are lead-free designs, some are made of copper and zinc which is very light. So that requires the extra length to achieve the same weight compared to a lead core projectile.
So with a longer bullet that you’re shooting, the faster the rifling twist needs to be to properly stabilize the bullet in flight.
Its important to have great stability because it means great accuracy as well.
What does the barrel twist mean?
The technical definition is that the twist rate refers to the rate of spin in the rifle barrel, and is represented in inches per turn.
It’s important that your barrel has an adequate twist rate to stabilize the bullets you’re shooting.
A barrel that is a 1:10″ twist means that the rifling will spin the bullet one revolution in 10 inches.
After the adoption of the M16A2, the military started using a 1:7 rifle twist, which was faster. The rifling made a complete revolution within 7″ now instead of 14.” We are talking twice as fast.
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.
Some shooters are greedy and they want a barrel twist that can excel with the heavier 77 grain or 85-grain loads, but at the same time to be able to smoke some woodchucks or prairie dogs. In other words they would like a 40-grain bullet to shoot accurately?
So this is a common question. Can you “over-stabilize” a lighter bullet with too fast of a rifling twist?
The quick answer is that an over-stabilized bullet is not conducive to accuracy, but it is only noticeable in extreme cases of over-stabilization and at very long range. You’d never notice it at hunting distances.
While in-flight the bullet travels along its downward arc with its tip pointing skyward, exacerbating wind drift and hastening velocity loss.
Ideally, the tip of a properly stabilized bullet should tip downward as the bullet begins its downward arc.
It is true that heavier, longer bullets in the 69-85 grain flavors like faster rifle twists of 1:8, or 1:7.
Shooting for Results
Here’s an experiment that was run by K Whitmore a gun enthusiasts and editor, he was trying to see if the AR barrel twist rate really matter, his approach is on a practical level but not scientific, here’s his take on this:
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.
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.
The second rifle is a factory Bushmaster Minimalist that Remington had me use on a hog hunt down in Texas at the Spike Box Ranch.
The only thing I added to this rifle was an ACME Machine 1-8x28mm FFP low-powered variable optic.
Here’s the ten different bullets from the lightest grain to heaviest shot:
-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
-Barnes 55 Grain TSX
-Remington 55 Grain PSP
-Barnes 62 Grain TSX
-IMI 77 Grain OTM Razorcore
-Barnes 85 Grain OTM
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.
While this isn’t a comprehensive accuracy test for each load, this test shows a good representation of the accuracy potential for each load out of a 1:7 rifle twist barrel.
As you can see from the included photos, there was absolutely no loss of accuracy from an “over-stabilized” lighter/shorter bullet.
Both rifles tend to shoot roughly the same point of impact, varying across the whole spectrum of bullet lengths and weights at 100 yards.
Some conventional “wisdom” would dictate that my accuracy should have suffered greatly with the shorter/lighter bullets with a faster 1:7 rifle twist or worst case scenario tumble through the air and keyhole the target. This just isn’t the case.
But then again shooting at 100 yards isn’t the same as shooting out to 400-600 yards.
Within the normal ranges that most shooters fire their rifles, bullet length and twist should not be a concern if you have a faster 1:7 rifle twist.
If you’re fairly new to shooting and just getting into long range shooting. Keep things simple so that its easy to understand.
For example from K Whitworth’s test you could say:
With a 1:7 rifle twist, shooting quality ammo, you can go as light as you would like with commercially available ammunition.
About that “over-stabilization” you can bring have more issues at longer 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 that.
If you’re on a budget and you want up-close shooting that is within 300 yards, use bulk 55 grain M193 with a quality barrel.
It’s easy to get swept up in trying to figure out the “perfect” twist rate. But the fact of the matter is that getting it down to the minute degree, for the casual shooter, is largely a theoretical exercise.
If you’re contemplating the rate of twist for your next custom build, I suggest you save yourself the aggravation and ask your gunsmith what he suggests for the bullets you plan to shoot.
That way, you end up with a rifle that shoots a variety of loads well, rather than a fickle rig you’ll give up on.
We obviously didn’t cover all the different types of rifles, this was mainly on the AR.
So for an AR for simplicity stick with a 1:7 rifle twist.
Let us know what you think below in the comments.
Some other recommendations from ClearAdvantageTV
1:9 40-62 grain Shorter lighter bullets
1:8 55-75 grain
1:7 62-77 grain bullets
Sources: K Whitmore (photos)
[su_dropcap style=”light” size=”5″]I [/su_dropcap]recently purchased a .52-caliber barrel from Charles Burton of Flintlock Construction Inc. (FCI) in northeast Kentucky, and I’m happy to report that it now has a new riﬂe wrapped around it and is performing very well.
My shooting was done using a .512-inch-diameter round ball wrapped in a .015-inch patch. The bore is tapered – just a mere .003 inch within the 35-inch length – but it is easily felt both when loading a patched round ball and when cleaning the gun. That ball-and-patch combination is relatively easy to start at the muzzle, and ramming the patched ball down to rest on the powder actually gets easier as the ball is pushed further down the
bore. At least part of the reason for that is because the tapered bores have their tightest diameters at their muzzles.
These barrels can be straight octagon up to 1 3/8 inches in width for any length out to 48 inches. FCI also offers straight tapered barrels to those same dimensions. Swamped, octagon and round barrels are also available out to 48 inches as well. Smoothbore barrels are made out to 48 inches. Burton also makes a 1 1/8-inch light bench barrel with a false muzzle, and pistol barrels too.
Burton’s barrels are made from 12L14 steel, and several calibers are standard. These include bore sizes of .30, .32, .36, .38, .40, .44, .45, .47, .48, .50, .52, .54, .58, .60 and .62 calibers. What drew my attention to his barrels is his offering of the .52 caliber, and that is what I ordered: a 35-inch barrel that is 1 inch wide with a twist rate of one turn in 66 inches, and having ﬂat bottom grooves. All barrels come with a straight or tapered tang breech plugs and the riﬂing is cut with seven grooves. Twist rates can be from one turn in 21 inches to straight riﬂed, so the buyer has the choice of just about any rate of twist desired.
SQUARE-BOTTOM RIFLING GROOVES are cut to a depth of .010 to .012 inch, while round bottom grooves are cut to .015 to .016 inch. All riﬂed barrels have seven grooves, and typical twists are 1 in 48, 1 in 57, 1 in 66, and 1 in 72 inches. But by using a sine bar riﬂing machine, Burton can cut twists from straight to as fast as one turn in 21 inches.
In addition, he hand laps and shoots all custom barrels before shipping them. My .52-caliber barrel came with a test target that was ﬁred from sandbags at 30 yards with 70 grains of FFFg under a patched .512-inch round ball. In order to shoot the new barrels, Burton temporarily breeches them to an in-line “action” and glues sights to the barrel. All evidence of the sights and the breeching are removed before the barrel receives the breech plug the customer has requested.
When it was time to sight-in my new riﬂe the day was wet and rainy, but I just wore my hat with the “Montana peak” and went shooting. For the initial shots, I posted a target at 25 yards and ﬁled down the front sight to raise the point of impact on the target. The load used for these close-range tests was 50 grains of GOEX FFFg under the .512inch cast ball wrapped in a Bridgers Best .015-inch lubricated patch.
With the sight ﬁled so the riﬂe was hitting center, I posted a pistol target for a ﬁve-shot group, and this turned out very well indeed. Those ﬁve shots, by the way, were ﬁred using the Pushing Daisies patches from October Country, cut from .015-inch ticking and lubed with Bumblin’ Bear Grease. Both are very good patches, especially for hunting. In case you are wondering, I consider both Bridgers Best and October Country patches to be equally good.
All things considered, the Burton barrel with the tapered bore loads easily and shoots very well. The small amount of shooting I’ve done with this riﬂe probably hasn’t done the barrel any real harm, but more shooting will certainly be done – and sooner than later.
Prices for Burton Barrels vary, but all are very reasonable, starting at $185 for a breeched straight riﬂe barrel, such as mine. Prices do not include shipping, and Burton asks for 50 percent of the barrel’s cost when an order is placed, with the remainder due when the barrel is received. Delivery is generally made in three to six months, as no barrels are kept in stock. All barrels are for black powder only.
To learn more about Burton gun barrels, or to place an order, visit fcibarrels.com, or call (606) 780-7709. ASJ
[su_dropcap style=”flat” size=”5″]A[/su_dropcap]lthough organizations are recognized (and occasionally honored) for manufacturing the products they market and sell, it’s really the the people who own, manage and work at those companies who have the passion and skill to make those products truly great on a daily basis.
As the market for ARs and AR parts continues to grow, companies staffed by people who love ﬁrearms continue to make their way to the outdoor industry, and the team at Spinta Precision is no different.
Spinta Precision was formed three years ago as a sister company under the corporate umbrella of S.H Industries, a manufacturer of high-performance automotive products.
“We started off manufacturing forged wheels,” Spinta’s Sam Hong told us recently. “Most of our business came from private labeling and contract work for other wheel companies. I have a passion for cars, but even more so for guns. We eventually transitioned from forged wheels to AR15 barrels.”
Although the Spinta spinoff only produces products for the shooting sports, the company name is in homage to Hong’s “other” passion.
“My nickname on the racetrack used to be ‘Boost,’” Hong said. “I was the guy trying to squeeze every p.s.i out of my turbos with a boost controller. I have a soft spot for a 1987 Buick Grand National, early ’90s 300ZX twin turbo and Italian cars. The name Spinta comes from the word ‘boost’ in Italian.”
The ﬁrst product offering under the Spinta banner was a 264 LBC barrel.
“We wanted to offer an affordable solution to our customers who wanted to shoot 6.5 Grendel,” Hong related. “Our next project was to offer an affordable solution to building a 9mm AR.”
At Spinta, the product development cycle often begins outside of the corporate offices, and several parts currently in production began as customer requests via email or over the phone.
“We listen to our customers,” Hong said. “We have built a loyal customer base not only by offering a product but backing it with some of the best customer service you will ﬁnd in the industry.”
The system seems to be working just ﬁne. Spinta recently took delivery of new equipment and has doubled production. Even more impressive is that the company is succeeding in California, a state not known for its support of the gun industry.
“We call this state Commiefornia because of the ridiculous laws,” Hong related. “We have thought about moving out of state multiple times, but with Californians losing their gun rights every year, we don’t want to abandon ship.”
For more information, see spintaprecision.com. ASJ
[su_dropcap style=”light” size=”5″]H[/su_dropcap]ow did 4D Reamers become the leading name in custom reamers, barrels and tools in the gun industry? We spoke with owner Fred Zeglin, who comes from years of gunsmithing in the industry and is sought after nationwide for his expertise on precision and gunsmithing.
American Shooting Journal What makes you the expert?
Fred Zeglin Most importantly, we are staﬀed by highly gun-literate people, but personally, I graduated from the Lassen College Gunsmithing program back in 1984. I have made a living in gunsmithing and custom guns for over 30 years now, and I’ve published two books, Wildcat Cartridges and the Hawk Manual. My next project is to put together several instructional booklets about gunsmithing.
Not too long ago, I was approached by the American Gunsmithing Institute to make instructional video courses, and I created two videos: Taming Wildcats: Custom Cartridge Design and Fabrication and Reloading A to Z. I have both taught and run NRA Short-term Gunsmithing programs, and coordinate and teach the Firearms Technology program at Flathead Valley Community College.
ASJ It sounds like your scope and depth of knowledge is profound!
FZ In a nutshell, I have chambered and headspaced so many barrels that I lost track of the count long ago. Because of my work developing cartridges for clients and for my own interest, I was forced to learn about headspace at a level that most gunsmiths never feel the need to understand. If you’re going to design new cartridges, understanding headspace is essential.
ASJ It sounds like you enjoy teaching. What is your philosophy when working with students?
FZ When you teach classes it’s necessary to carefully break down the processes you’re discussing to make sure you impart the information the students need. This close evaluation of processes will increase your understanding of the subject in a unique way. If you are teaching others how to headspace a barrel, you better know exactly what you’re talking about.
ASJ Your company name is 4D Reamers. Is that all you oﬀer?
FZ We are constantly adding new tools. Right now we have almost a thousand reamers. In addition to that, we have headspace gauges that work with the reamers and a lot of other gunsmithing tools.
ASJ What other tools do you rent?
FZ We have some AR-15 specialty tools, sight installation pusher tools for several popular pistols, shotgun choke tools in several patterns and gauges, hydraulic dentraising tools for shotgun barrels, specialty taps and dies, crowning tools, forcing cone tools and lots more. Essentially, if it’s small enough to ship in the mail, we might well have it.
ASJ Tell us about the quality of your tools.
FZ We’re often asked if the reamers are sharp. I really have to laugh when I hear that question. I understand the reason that people feel the need to ask, but the answer is right in front of them. We have been in business a long time and repeat customers are our life blood. So, we make every eﬀort to keep all the tools in the best possible condition. We want our clients to come back over and over. If we did not provide good tools, this would not happen.
ASJ Who is your typical client?
FZ That’s an interesting question. We have a lot of hobby gunsmiths and guys who just want to ﬁx up one gun. We also serve the professional gunsmith community; professionals rent more tools simply because they have the volume of work.
A few of our professional clients are benchrest gunsmith Gordy Gritters, Pac-Nor Barrels, Jack First Distributors, Brockman’s Riﬂes. You know these folks have great reputations with their clients and they would not do business with us if we did not take good care of their needs for sharp, quality tools.
FZ When tools return they are inspected under magniﬁcation. Most clients are very careful with the tools. They understand that the next time they need a reamer they will want a sharp tool, so being responsible with them is just natural for most clients.
Once in a blue moon a tool will be damaged. What I like about the gun business is that it’s populated with people who are all about personal responsibility. Most are nice enough to call up and tell us there is a problem; some write a note and send it with the tool. In nearly all cases they simply abide by the rental agreement and take care of the damage.
When a tool shows wear and needs to be sharpened, we ship them oﬀ to professionals who specialize in this. We endeavor to make sure every tool is sharp and in good condition. We encourage clients to call right away if they are unhappy for any reason. Happy clients come back, that’s what we want.
ASJ Why do people rent tools when they can buy them?
FZ If we are talking about a hobbyist gunsmith, tools can be rented for a tiny percentage of what they cost to purchase. Save money on tools and you get to do more projects – it’s simple math.
Professionals use us because they often need tools that they will only use once or twice during their whole career. We often hear, “I have a tool box full of reamers that I never use.” Obviously that’s a huge investment in tools that just lay around. Shops will purchase reamers for calibers that are popular in their area. But the one-oﬀ chambers are better handled by ordering a rental. The overhead cost is so much lower and most shops just charge the rental to the client, so there is no investment at all for the shop. Plus, they can oﬀer every chamber we have tools for without buying a single one. If we have 1,000 reamers, they have 1,000 reamers.
ASJ Do you ever sell reamers?
FZ On a custom order basis we do sell reamers and gauges. Most of these orders are for non-standard reamers. Some folks want special dimensions, so custom orders are the best solution to that requirement. We are not a reamer maker, so we buy all of our reamers from the various reamer makers across the country.
We also sell Dakota bolt knobs in ﬁve styles, Dakota grip caps and inserts, Cerosafe chamber casting metal, instructional videos and many other gunsmithing-related products.
ASJ You also sell barrels. Tell me more about that.
FZ We oﬀer custom Savage drop-in barrels. These barrels are for the popular Savage 110 family of bolt actions. There are many places you can order pre-ﬁt Savage barrels, but what we oﬀer is access to our library of reamers. If we have the reamer, you can have a barrel chambered for the caliber. Nobody has as many calibers to choose from as we do.
We will only stock barrels that we know we can count on to be accurate. Blanks are CNC turned to the taper of the client’s preference, and we handle all the chamber and crown work in our shop, so that we can assure a proper set up for accuracy.
Stainless steel and chromoly (blue) steel barrels are both available. We have a small stock of blanks that we list on the web site. Custom orders can be ﬁnished in as little as four to ﬁve weeks, depending on the speciﬁcs of the order, and we are competitive on price.
Our accuracy speaks for itself. We have yet to have a client complaint. I love that ability to provide a high-quality product that surpasses the client’s expectations. ASJ
Editor’s note: For more, see 4-dproducts.com.