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.
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.
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.
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.
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.
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.
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.