The Long-Range AR-15, Part 2

By Glen Zediker published on in How To

In Part 1, I described the path the AR-15 took to become a viable longer-range rifle, and so now let’s look at where it is now.

To hit a target 500+ yards away, rifle configuration or component specifications are the first keys. Key numbers one and two are bullets and barrels. Of course, there has to be capable ammunition involved. For extended distances, that’s a handload, currently.

Right now, there is no viable commercial ammo for .223 that is adequate for anything much past 300 yards. In the competition world, a Sierra 77-grain bullet, for example, is not considered a good choice for a 600-yard event. The Sierra 80 is. It’s not the extra three grains, not even a little bit. It is the style of the bullet, which is also to say its shape.

AR Sierra Match King 80gr 77gr 69gr

The bullet is the big deal. This Sierra Bullets lineup (left to right) is an 80-grain MatchKing, then the 77-grain MatchKing, then the 69-grain MatchKing. The 77 is a little more effective than the 69, but at long distance, the 80 is way better than either. Get a minimum of 1-8 twist for your long-range project rifle.

The 80 is much more aerodynamic. It is also longer, and too long to realistically be seated within the case neck to provide a short enough overall cartridge length that will fit rounds into a box magazine. If 2.25 inches is good to use for a maximum magazine-length round (and it is), then the 2.35+ inches necessary to load an 80-grain bullet to provide minimum suitable bullet cartridge structure (meaning suitable engagement area within the bullet shank and the case-neck contact areas) is well beyond the constraints of the magazine. You must feed rounds constructed with 80-grain bullets one at a time into the rifle.

(Important note: I refer to “80-grain bullet” because it’s common, and performs well. There are others that are similar: lighter-weight VLD-style bullets, high-BC 75-grain designs, and even 90-grain bullets. Point is, is, that these are also all too long tip to tail to be seated deeply enough to fit a magazine box.)

To stabilize anything longer than a 68 or 69-grain bullet, the barrel twist rate must be—at minimum—1-in-8. Twist rates reflect how far the bullet travels along the lands or rifling to make one complete revolution. So, 1-in-8 (or 1-8, 1:8) means “one turn in eight inches.” I think it’s better to go a little faster in twist. There is nothing wrong with a 1-7 twist. The 90-grain bullets require a 1-6.5, and that is getting on the quick side. If you want to shoot Sierra 77s or equivalent, and certainly anything longer, 1-8 is necessary. By the way, it is bullet length, not weight, which constitutes the necessary twist rate to launch a stable bullet.

Two AR Barrels

The barrel on the right shoots every bit as well as the one on the left, but weighs a whopping lot less. It’s not at all necessary to run a straight taper barrel (bull-style) for great perforation at long range.

Floating a match-grade barrel (and defining that term will be a whole ‘nother article) of the correct twist rate is really the only technical “trick” necessary to get good groups from an AR-15. The “float” part comes from the installation of a tubular-style forend. These designs house the barrel with no contact points along the length of the tube. The gas block and gas tube are affixed to the barrel, certainly, and for this reason it’s critical that the gas tube has zero contact at the point where it passes through the upper receiver.

Barrel length is not nearly as influential with .223 as it is in larger-bodied cartridges. The relatively small amount of relatively faster-burning propellant just doesn’t get the gains from extra inches of barrel length like, say, a .223 WSSM will. The difference between an issue 20-inch and an aftermarket 24 is about 80 to 100 feet per second, using proven suitable propellants. That, yes, is influential. (2550 fps from a Sierra 80 is competitive.) Point is, there is only a scant difference between a 24-inch and a 26-inch, or more, barrel in a rifle chambered for .223.

Likewise, large-diameter barrels are of no discernable value to accuracy. Extra weight is about the only benefit, but most of those “bull”-type barrels are way too heavy. There is no recoil to speak of, as it is, certainly not enough to dampen with barrel weight. Anymore, I run a 0.800-inch taper that steps down for a gas block and then straight on 0.750-inch diameter to the muzzle.

AR Tubb Buttplate

This Precision 4-Way Adjustable Buttplate for fixed-stock rifles is made by David Tubb. The shooter can adjust the buttplate for length, buttpad height, cant, and offset from the mat using one wrench.

Another vital aspect of more successful shooting over more real estate is getting the rifle to fit the shooter better, which is to say to help the shooter employ a more effective position. An adjustable buttstock is valuable, and even more valuable if it’s well-designed. Mostly, a standard stock is too short, and the cheek area sits too low. Adding length helps a lot by itself. There are assemblies that replace the standard buttplate to allow for length and, usually, height and rotation adjustments for the buttpad. An elevation-adjustable cheekpiece is a big help to attain a solid position.

AR CSS Adjustable Stock

This is a fully adjustable stock from CSS. The cheekpiece is easily adjustable from position via a rotating cam apparatus. Most adjustable-cheekpiece-outfitted stocks force the head too far back, but this one doesn’t, according to the author.

A solid position is one the shooter can settle into without any undue strain to maintain the head where it needs to be to get a good sight view. Ideally, when the face is resting fully on the stock cheekpiece, the view through the sight should be dead-centered and clear. Muscle tensions necessary to clarify and correct the sight view ultimately lead to discomfort and muscle fatigue, and that leads to the shakes. Shakes and centered 1000-yard shots are not normally coincidental.

The charging handle kills the effectiveness of most designs. The cheekpieces are set too far back to allow clearance for charging. The only real way around it is a modification whereby an operating lever is threaded into the side of the bolt carrier, and the need for the charging handle is done away with.

Leupold Vari-X 8.5 - 25x50mm Scope

Shooting at longer ranges requires the marksman to see the targets. The Leupold Vari-X III 8.5-25x50mm offers clear images and precision adjustments.

Correct optical sight positioning can be a challenge. With a flattop upper, I need a good inch additional forward extension at the muzzle side of the upper for the sight mount bases to avoid holding my head “back” to get the optimal view through the scope. A longer rail piece is necessary for my builds as a result.

AR Bubblevel

At longer ranges, the consistency of the rifle’s attitude (degree of levelness shot to shot) is a significant influence on accuracy. With a bubble, it doesn’t matter if the rifle is upright or not, just that the bubble has been adjusted to show the same orientation each time. The best I have used is a design by David Tubb that mounts on the scope body. It’s out of the way and easy to read.

Last, a good trigger works wonders… Much more about those in future installments.

Without a doubt, anyone’s success as a longer-range shooter has a whopping lot to do with skill. The rifle might group well enough to center impacts on distant targets, but if the shooter’s holding ability, shot-production skills, and conditions-evaluation accuracy and application aren’t supporting that potential, then that’s what he’s left with. Potential.

It’s a book in itself, maybe two, to address ideas on honing ability and developing the right kind of experience to become a master of longer-range shooting.

What ammunition and accessories do you use when shooting long distance with your AR? Share with us in the comment section.

SLRule

Glen Zediker has worked professionally with some of the greatest shooters on the planet, as well as leading industry insider rifle builders, manufacturers, and proven authorities on gunsmithing, barrel-making, parts design and manufacture, and handloading. And he does pretty well on his own: Glen is a card-carrying NRA High Master and earned that classification in NRA High Power Rifle using an AR-15 Service Rifle.For more, please visitZedikerPublishing.com or call 662-473-6107 (weekdays 9-4 CST). Write to P.O. Box 1497, Oxford MS 38655.

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Comments (67)

  • David Farber

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    I have a Mossberg MVP with a 24 in. 1:9 medium bull barrel and I can shoot 75 gr. Hornady HPBTs sub MOA at 600 yards all day. 70gr Berger VLDs do quite well too. So at least some 1:9 barrels can handle heavier bullets. I understand the concept but the Hornady’s length to weight ratio must be able to handle it. Hornady recommends 1:8 or better for the 75gr AMAX.

    Reply

    • Huuf Arted

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      As the author said its the Bullet SHAPE that determines the Rate of Twist required rather than it’s WEIGHT…

      Reply

    • Benson young

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      It’s not the shape nor is it the weight! It is the length of the projectile. You may say that the longer the bullet is, the heavier it is also. Not true at all. Example: Barnes TSX

      Reply

  • lee

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    I remember hearing about journalist saying that we are now using “buzzsaw” bullets after hearing the whiring noise of bullets being glanced off of twigs and branchies…from our m-16’s…and the rifling of 1:12 so that shows you the amount of ballistics inspecction our govt.! why not just use 1:8 alaround this should take care of all bullet wieghts…. am I wrong about this….thanks. for listening!

    Reply

    • JIMO

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      Our army generals Probably try to tell the Obama administration (government) about the rifling and ricochets and told him it was not a good idea To have rifling 1:12. But as you know Obama Doesn’t want to be told by those who know so he fired them and did his own thing. Obama has no knowledge of this and yet he sends you into battle with inferior weaponry. Obama and his staff have no common sense at all! He wants to tear down our military and he’s doing a good job doing it!

      Reply

    • Huuf Arted

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      Bullet stabilization is not always the main goal in military designs. The M-16 is thought to benefit in stopping power by using low stabilization rates that cause the bullet to key hole upon impact.

      Military thought for extended range fighting usually involves different weapons rather than different ammo i.e. 5.56 vs 7.62 etc.

      Reply

    • JIMO

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      Going into combat would you like to have a 22 caliber going up against A 30 caliber that the enemy has? It doesn’t matter if you shoot A 22 caliber through brush at 10 yards or 100 yards, it will still ricochet! The 30 caliber would punch through the brush and hit its target! (Physics).

      IS WAR A MILITARY EXERCISE OR A GAME TO THE U.S.??????
      WHY IS IT THAT THE U.S. GOES INTO COMBAT WITH ‘UNDERPOWERED’ AMMO COMPARED TO OUR ENEMIES?????? (SENDING US OFF TO WAR WITH A .22 RIFLE)!!!!!!

      NOTE: A .30 (.308) CALIBER (M-14, AK-47 -WHICH OUR ENEMY USES).
      -A .223 CALIBER (.22 CAL.-M-16- WHICH THE U.S. FORCES USE.)

      IF THE HARMONICS OF THE RIFLE ARE CORRECT, THEN A .223 CALIBER IS SUPPOSED TO TUMBLE WHEN IT HITS FLESH AND CAUSE EXTENSIVE DAMAGE…OR SO OUR GOV’T. SAYS… BUT DOES IT WITH MOST M-16 RIFLES? ALOT OF TIMES YOU WOULD NEED MULTIPLE HITS TO KILL…..THAT IS WHY THE M-16 HAS A SETTING FOR THREE SHOT BURSTS, THEREFORE USING MORE AMMO IN A FIREFIGHT!….IF AN M-14 HIT ITS MARK, YOU WOULD HAVE “ONE SHOT = ONE KILL”. THE M-14 WAS MORE ACCURATE AT LONGER DISTANCES ALSO. I REALIZE THAT THE M-14 IS HEAVIER THAN THE M-16…. BUT WHEN YOU ARE IN A FIREFIGHT, ADRENALINE TAKES OVER AND YOU DO NOT NOTICE THE WEIGHT OF THE RIFLE OR THE AMMO.

      THE SMALLER SLUG (.223) WILL RICOCHETE OFF OF LIGHT BRANCHES AND MISS THEIR TARGET, BUT THE .30 CAL WILL PUNCH THROUGH LIGHT BRANCHES AND HIT THE TARGET…..AS WELL AS DESTROY BRICK AND CONCRETE WALLS TO EXPOSE THE ENEMY.

      I AM SURE THAT THE (WEAKER ROUND-.223) THE U.S. HAD TO FIGHT THE ENEMY WITH WAS A LARGE FACTOR TO CAUSE MANY AMERICAN SOLDIERS THEIR LIVES!!!

      SHAME ON THE GOV’T. FOR TRYING TO SAVE MONEY INSTEAD OF HAVING ‘COMMON SENCE’ TO SUPPLY THE U.S. WARRIORS ENOUGH FIREPOWER TO BE AT LEAST EQUAL OR BETTER THAN OUR ENEMY!!! (…AND DON’T TELL ME THAT OUR GOV’T. MONEY GRUBBERS DIDN’T REALIZE WHAT THEY WERE DOING. OUR SIDE HAD SPIES AND KNEW WHAT THE V.C. HAD FOR WEAPONS WAY BEFORE WE GOT INVOLVED WITH THAT V.N. ‘CONFLICT’.

      THAT WAS AS BAD AS WWII WHEN OUR GOV’T . GAVE US SHERMAN TANKS WHICH WERE UNDERPOWERED AND INADEQUATE AGAINST THE GERMAN TIGER TANKS! AGAIN, OUR GOV’T. HAD U.S. SPIES THAT GAVE THE INTEL OF WHAT OUR ENEMY WERE USING BEFORE WE GOT INVOLVED.

      I REALIZE THE MILITARY IS CHANGING SLOWLY BACK TO THE LARGER ROUNDS OF .30 CAL. AS WELL AS LARGER CALIBERS. MAYBE THEY REALIZE THEIR MISTAKE AFTER-THE-FACT. (OR PROBABLY IT WAS A POLITICAL PLOY TO MAKE MONEY FROM THE M-16 GUN MANUFACTURERS)?

      JIMO
      A VIET NAM WAR COMBAT VET…1964-66 (THE LONGEST YEAR OF MY LIFE)
      100% TOTAL AND PERMANENT DISABLED. (THANKS GOV’T.)

      COMMENTS WELCOMED…..

      Reply

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