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What is the Best AR-15 Barrel Length for Your Needs?

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When you build a rifle, every choice you make has weight. Every part represents a tradeoff: one thing prioritized, another sacrificed. In the case of barrel length, that weight is literal as well as figurative, as every inch of length is a few extra ounces you’ll have to carry. 

Barrel length is one of the defining features of a rifle. Two rifles intended for the same purpose might have different receivers, grips, stocks, bolt carrier groups, or rails, depending on the preferences of their users, but they will almost always have very similar barrel lengths because that length is inextricably tied to their ability to perform their set task. 

Choosing the right barrel length means walking a tightrope between velocity and weight. Too long, and you slow yourself with excess weight. Too short, and you handicap your ballistics. 

Below, we’ll take a look at how barrel length affects AR-15 performance, how to choose the right barrel length for your application, and some of the most popular barrel lengths currently on the market. 

COM Geissele AR15 Barrels 02

Understanding AR-15 Barrel Lengths

The primary dichotomy of barrel length can be understood as weight vs. velocity. All else being equal, a longer barrel will be heavier but offer greater velocity, whereas a shorter barrel offers the inverse. Once you start to look at different barrel profiles and materials, there is some wiggle room, but the general principle still holds true. 

Accuracy, on the other hand, is a much more complicated topic. Technically, longer barrels are not any more accurate than shorter ones, and may even be less accurate, although not in any practically significant way. 

Mechanical accuracy (The accuracy of the rifle itself with all human variables removed) is the result of a myriad of factors, including rifling quality, barrel design, rigidity, crown symmetry, and more, but barrel length isn’t really one of them, except for how it affects rigidity. Practical accuracy (The accuracy of which a typical shooter is capable with the rifle), on the other hand, can be impacted by velocity, particularly if the target is at an unknown distance. 

When engaging a target at an unknown distance, a marksman will need to estimate both that distance and the drop of the bullet at that range. Higher muzzle velocity leads to a flatter trajectory, which is more forgiving of poor wind or range estimates. If, on the other hand, you engage targets at known distances and have plenty of time to punch your calculations into a ballistic calculator, velocity becomes considerably less important—although still relevant, particularly for the longest shots where wind becomes a defining factor. 

Lastly, your barrel length will have a direct impact on your rifle’s maneuverability. In many cases, this is a non-issue; ranges, forests, and vistas all have plenty of room to move around, regardless of your rifle’s size. For home defense or professional use, though, maneuverability can be essential. 

The overall length of your rifle—particularly the barrel length—will have a direct impact on your ability to move around corners and through tight spaces. In the case of home defense, in particular, weight and length will determine your ability to hold your rifle upright and on target with one hand, while the other operates door knobs, light switches, or a phone to call 911. 

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Factors to Consider When Choosing the Best Barrel Length 

As with most decisions related to building the best possible AR-15, the primary factor to consider when determining barrel length is how your rifle will be used. 

A large part of this will be effective range, which is different from maximum range, although both are impacted by velocity. Maximum range can be considered as the absolute farthest distance at which you can reliably hit a target, whereas effective range is the furthest distance at which you can hit a target and have the round deliver a sufficient terminal effect. 

The nature of this terminal effect will vary depending on your target. For a paper target, you only need to be able to perforate the cardboard. For a deer, though, you need to be able to deliver enough kinetic energy for an ethical kill, which is why the effective range of a hunting rifle might be very different from that of a target rifle, even if the caliber and velocity are identical. 

When selecting a barrel length, a good place to start is by determining what effective range you require, then calculate or research what muzzle velocity you will need for your cartridge to deliver adequate terminal performance. Once you know that, you can safely eliminate every barrel too short to achieve that velocity. 

In some cases, (.223 Remington and 5.56 NATO ammunition being one of them) your specific type of ammunition will impact your effective range. Traditional 55-grain ball ammunition relies on high velocity to achieve yawing and fragmentation, both important elements of its terminal effectiveness, but other types of ammo rely on expansion from a hollow or soft lead tip, which may be less sensitive to velocity. As such, it’s important to consider the type of ammunition you will be using as well. 

Mobility and maneuverability are important considerations too, at least for some applications. Longer barrels take longer to swing between targets at moderate ranges and can be downright cumbersome at close range or inside structures. While there are techniques that can help ameliorate these drawbacks, such as short-stocking, there’s no substitute for a short barrel and a proper grip and cheek weld. 

However, barrels shorter than 16″ or equivalent with a pinned and welded muzzle device can verge into NFA territory, requiring additional paperwork and regulation to own and use. 

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Popular AR-15 Barrel Lengths 

While there is a vast range of different lengths out there for AR-15 barrels, most users will find themselves gravitating towards a few mainstays, and with good reason. The most popular barrel lengths are popular because they work well and offer an optimal balance of characteristics for their role.  

It’s worth noting that the sections below represent some of the best barrel lengths for 5.56 NATO and .223 Remington, but not necessarily other cartridges. While many of these barrel lengths are popular with alternative cartridges like .300 Blackout, 6.5 Grendel, or .350 Legend, those cartridges have different very different ballistics and sometimes benefit from other barrel lengths.  

All-Purpose Barrels: 16-inch & 14.5-inch

Far and away the most popular barrel length for an AR-15 is 16″. This medium length offers very capable ballistics, with a maximum range exceeding 500 yards, and in some cases quite a bit further, although that will depend upon factors beyond barrel length. 

Despite their considerable range, 16″ barrels remain handy enough for most medium-to-short-range target engagement, although you may find them a bit cumbersome in the tightest of environments. 

Primarily, though, 16″ barrels are popular because they are the minimum length allowable by law without dipping into NFA territory. Most users have neither the need to shoot their rifle to the limits of its range, nor the facility to do so, and so commonly opt for the shortest barrel that doesn’t involve an extra wait or paperwork. 

14.5″ barrels also fit into this category; despite the 1.5″ difference in length, they offer very similar ballistics to 16″ barrels, to the point that the difference is immaterial for the vast majority of applications. Unlike 16″ barrels, though, 14.5s require a pinned and welded muzzle device which brings the total length to over 16″ to avoid running afoul of NFA laws. 

As such, they offer the promise of a slightly handier rifle, but without the ability to easily change muzzle devices in the future. 

Home Defense/ Short Range Barrels: 11.5-inch & 10.5-inch

For short-range tasks such as home defense, two barrel lengths remain popular: 11.5″ and 10.5″. 

10.5″ barrels are commonly regarded as the shortest viable barrel for an AR-15, unless, of course, you want to change calibers to something like .300 Blackout. Technically, 10.3” is the shortest viable barrel length, but with less than a quarter inch of difference between them, we’ve grouped them together for these purposes. A 2.23/5.56 barrel any shorter than 10.5″ compromises so heavily on ballistics, and gains little in maneuverability, since a 10.5″ barrel is already quite easy to move through even the most restrictive spaces. 

The drawback of 10.5″ barrels is, of course, velocity. Opting for such a short barrel hamstrings your velocity and thereby your range. However, it’s a rare man who has a home with a room or hallway longer than a few dozen yards, and so for home defense, many users ignore maximum range entirely and instead choose to build highly compact rifles optimized for indoor use. 

However, the alternative 11.5″ barrel length is also equally popular. While this length is obviously slightly longer, and therefore slightly less handy around corners and through tight doorways, the additional inch of barrel length adds significant velocity and boosts effective range by a fair margin. As such, it’s a popular “jack of all trades” option for those seeking a short rifle, but unwilling to entirely compromise on medium-range performance. 

Long Range Barrel: 20-inch

For long-range rifles, naturally, longer barrels are preferred. However, the longest barrels commonly available for .223/5.56 rifles (usually around 26″) are not the most popular. Instead, that distinction goes to the 20″ barrel length. 

A 20″ barrel offers exceptional velocity, enough to push most common 5.56x45mm NATO loads nearly to the limit of their range. While 26″ barrels can certainly eke out a bit more velocity, the increased velocity to weight ratio diminishes significantly after 20″. As such, many marksmen opt for the slightly handier 20″ barrel length and make do with a few less feet per second of muzzle velocity. 

While 20″ may sound like a lot of barrel, it’s not so long as to entirely preclude the rifle from being used at short to medium ranges. The M16, once the standard issue rifle of the U.S. Armed Forces, featured a 20-inch barrel, which, while perhaps not ideal for close-quarters engagement, proved adequate for several decades. 



When building or buying a rifle, barrel length is an important part of the picture. The length of your barrel will factor heavily into your rifle’s range and mobility and must be matched properly with your intended application. 

To choose a barrel length, start by determining the maximum range you require from your rifle, then consider how much weight and length you can tolerate.