AR-10s are some of the more versatile guns on the market; while their high caliber does preclude them from being used for certain applications, such as small game hunting or most home defense, they still remain a viable option for medium game, competition, long-range precision, and more.
To make the most of your AR-10, though, you’ll need to choose a proper barrel for your cartridge and application. Attributes like barrel length, material, contour, and more will all play into how your firearm handles and performs ballistically.
Below, we’ll take a look at the most popular AR-10 calibers and how to best capitalize on their capabilities with an optimal barrel.
Common AR-10 Calibers
AR-10s are available in an absolute smorgasbord of calibers, ranging from the old standard 7.62×51 NATO to modern niche rounds like 8.6 Blackout. There are dozens of rounds in between, each with its own purpose, advantages, and drawbacks.
But, the vast majority of AR-10s sold in the US are usually in one of two calibers: .308 Winchester and .6.5 Creedmoor.
.308 Winchester/7.62×51 NATO (for those unfamiliar with the difference between .308 Winchester vs 7.62×51 NATO, we recommend our article on the subject) remains the default cartridge for AR-10 rifles. It’s an excellent do-all cartridge, capable of everything from hunting and 3-Gun style competition to long-range precision. It’s something of a jack of all trades—rarely the best round for the job, but always a good one.
While it shows its age in roles like long-range marksmanship with a merely average ballistic coefficient and somewhat mediocre drop profile, it’s still fully capable of effect hits out to at least 800 yards, with further distances being possible depending on the barrel length, load, and of course, marksman.
6.5 Creedmoor, on the other hand, is a more modern rifle round with an impressive ballistic coefficient and exceptional efficiency at long range. With appropriate loads, it manages an effective range of 1200 yards or more.
Additionally, the 6.5 Creedmoor benefits from a softer recoil impulse, making it a strong option for tactical or hunting applications that require quick follow-up shots. For competition, though, it offers few advantages—while .308 can be competitive in Heavy Metal divisions, 6.5 Creedmoor does not meet the minimum caliber requirements for most leagues, meaning that it would be competing against the popular softer-shooting .223 Remington rifles.
If you’re not sure which caliber you’d like for your next rifle, we offer a full analysis in our article on 6.5 Creedmoor vs .308 Winchester.
AR-10 Barrel Basics
AR-10 barrels are not all that dissimilar from AR-15 barrels, which most gun owners will have at least some experience with. However, because AR-10s use significantly different cartridges from AR-15s, their barrel requirements and best practices differ significantly as well.
A full breakdown of the difference between the two platforms is available in our article on AR-10 vs AR-15.
Length
The best length for your AR-10 barrel will depend heavily on the cartridge it is chambered in and the intended use. Barrel length is directly related to velocity, which in turn has a direct and sizable impact on ballistic drop profile. Longer barrels deliver more velocity, and as such are always going to be preferred for a long-range-dedicated firearm.
But, a longer barrel means more weight and a longer overall firearm, which can be cumbersome inside a hunting blind or during a competition stage. Increased size and weight mean little for a rifle that will only be fired from a stable, stationary position, but it can be very impactful for more active pursuits.
For an AR-10 upper chambered in .308 Winchester, 20″ is a very popular barrel length. This length takes advantage of the .308’s velocity and long-range potential without adding excess or unnecessary length to the rifle. But even at just 20″, your barrel is going to add quite a bit of weight to your AR-10 build and may be difficult to maneuver in tight environs.
AR-10s tend to be geared more towards long-range use rather than close-quarters applications, though, so the popularity of the 20″ barrel makes sense. For truly precision-dedicated rifles, barrels as long as 26″ are available, but these are more often seen on bolt-action rifles. AR-10s are often chosen for their rapid-fire capability in addition to their ballistic potency, and so a 20″ barrel is a popular and versatile middle ground.
For those who want a shorter, handier rifle, 16″ barrels are also quite popular for .308 AR-10s. Unlike AR-15s, which are popular in both SBR and pistol configurations with barrels as short as 10.3″, rifles chambered in a full-powered round like .308 Winchester rarely benefit from going any shorter than 16″.
A shorter barrel would yield a loud boom and a massive fireball from the still-combusting powder as it leaves the barrel, but little else. Since these barrels come at the cost of significantly neutered ballistics and possible NFA regulation, they’re relatively rare on .308s.
A 16″ barrel, though, avoids any need for a tax stamp and allows for a relatively compact rifle that still provides the ballistics necessary to make hits at 700-800 yards. This makes it a popular length for those who want to use their rifle for hunting—where the additional velocity and long-range potential of a longer barrel offer little advantage—or for competition, where a shorter rifle is often favored for it’s improved balance and swing time. It’s also a popular length for those who will be using a suppressor for the majority of their time, as it keeps the overall length of the firearm manageable.
A 6.5 Creedmoor barrel would be subject to much the same calculus but with slightly different specifics.
For long-range-oriented AR-10s in 6.5 Creedmoor, 22″ barrels are the most popular choice. 6.5 Creedmoor benefits heavily from longer barrels and higher velocities, as the faster speed allows it to take maximum advantage of it’s high ballistic coefficient. As with .308, longer barrels are available, but begin to become unwieldy and so are less popular with autoloading rifles.
For a more compact gun, 6.5 Creedmoor uppers with barrels as short as 16″ are available, but 18″ is often recommended as a minimum length. An 18″ barrel offers a significantly higher muzzle velocity while only slightly compromising maneuverability, making it a popular middle ground. At 16″, the muzzle velocity is sufficiently compromised that the ballistic drop profile of the round is not all that different from .308—while being, on average, more expensive per round—making it a suboptimal choice, unless the slight reduction in recoil is considered to be worth the cost.
Material
The vast majority of AR-10 barrels are going to be made of steel. While there are minor differences between specific varieties, they all perform similarly enough that most users needn’t concern themselves with the exact chemical makeup of their barrel.
In decades past, there was often great debate about the relative merits of stainless vs finished steel. Stainless barrels typically offered slightly greater precision than Parkerized or chrome-lined barrels while the latter generally provided superior longevity, particularly when subjected to rapid fire. In the modern era, the difference in accuracy potential between the two has narrowed, particularly with the rise of nitrided barrels, which deliver both durability and precision.
Nevertheless, many users still find stainless barrels to produce the tightest groups, at the cost of a slightly shorter barrel life.
Another option is to choose a carbon fiber barrel. The name is a bit misleading—carbon fiber barrels aren’t actually made entirely of carbon fiber but rather utilize an extremely thin steel barrel that is wrapped in carbon fiber for strength and rigidity.
Carbon fiber barrels are substantially lighter than all-steel barrels and offer exceptional rigidity, which usually translates into tighter groups. However, they don’t tend to disperse heat as well, which can be a concern if you plan on doing a lot of rapid fire. Carbon fiber barrels are also often quite a bit more expensive than steel ones, so you’ll pay a premium for the weight savings.
Contour
Barrel contour refers to the way the exterior of the barrel is shaped in order to disperse weight. Options range from ultralight or pencil contours, which utilize the minimal amount of metal possible to maximize weight savings, to bull barrel designs which maintain the diameter of the barrel at the chamber all the way out to the muzzle, prioritizing rigidity over weight. And, of course, there are a whole host of middle-ground options in between.
A thinner barrel like a pencil profile will offer less weight, but consequently less rigidity. The lower the rigidity of the barrel, the more it tends to “whip” or move around following a shot. This movement can slightly change your point of impact, particularly if your next shot is fired quickly before the barrel has a chance to settle. Because of this, pencil-profile barrels often exhibit larger groups when fired quickly.
Thinner barrels also tend to heat up more quickly on account of their reduced mass. Heat build-up is one of the more significant contributing factors to barrel wear, so if you plan on frequent mag dumps, a pencil profile may not be for you, as it will reach higher temperatures during rapid fire than a heavier barrel. However, lighter-weight barrels also cool more rapidly, so a thinner profile barrel can still typically handle short, infrequent bouts of rapid fire without much risk.
A thicker barrel offers the inverse, with greater rigidity—and therefore, precision—but more weight. This weight is not always a detriment, though, since the added mass can help dampen felt recoil.
There are a number of medium-contour barrels on the market, each with its own balance of shape and weight. These barrels try to find a middle ground, often tapering from a thicker width near the chamber to a gradually thinner one towards the muzzle in an effort to maximize the amount of rigidity for a given weight.
Compatibility
It’s important to note when choosing any AR-10 component that AR-10s are not standardized in the same manner as AR-15s. Not all parts will work with all manufacturers. Numerous different receiver patterns, gas lengths, and other factors all play into compatibility, so it’s essential to verify with the manufacturer that your barrel is compatible with your other parts.
Choosing the Best Barrel For Your Rifle
The best barrel for your AR-10 will depend heavily on the caliber and your intended application.
Long-range precision rifles, for example, typically utilize a relatively long barrel with a heavy contour to maximize precision and minimize felt recoil. For a .308, this will typically mean around 20″, while a 6.5 Creedmoor will often utilize a 22″ or longer barrel.
Hunting rifles, on the other hand, often feature these same barrel lengths, but with significantly lighter contours or carbon fiber barrels. This creates a lighter overall rifle that is easier to carry in the field without sacrificing muzzle energy. Those who often find themselves hunting in dense brush or from a blind may opt for a shorter barrel, though they will typically still be best served by a light contour. Hunting rarely, if ever, requires more than a handful of shots in a short time frame, and so the risk of heat buildup and the detriment of barrel whip seldom come into play in this application.
Those who intend to use their AR-10 for more short-range-oriented tasks such as competition or range practice are typically best served by a shorter barrel, usually 16″ for .308 Winchester and 16-18″ for 6.5 Creedmoor, but with a medium-contour profile. In this application, a heavy bull-barrel-style contour would add unnecessary weight and compromise balance and ergonomics, while a pencil profile barrel might suffer from poor groups or abbreviated service life.
Those who expect extremely demanding firing schedules, though, may still opt for a heavy barrel in spite of the drawbacks in order to maximize barrel life.
Conclusion
AR-10s benefit from a wealth of options for barrels and a wide range of viable applications, but to make the most of your rifle, you’ll need to match the former to the latter. By evaluating your caliber selection and intended use case, you’ll be well-prepped to choose the right barrel length, material, and contour for your rifle.
