Best Barrel Length for AR-15 – Practical Guide

Best Barrel Length for AR 15
Alfred Mendoza

Want to customize the length of the barrel of your AR-15 but afraid to waste your hard-earned money? Choosing the best size of the barrel may be crucial for others, but it should not be. 

Let us dive into some of the best options and weigh everything before a trade-off.

AR-15 is one popular semi-automatic rifle loved by everyone because of its customizable build. One thing you can customize is the length of the barrel of this gun. The barrel lengths affect the handling, accuracy, and reliability of the weapon. 

But as modern rifles arise, advancement in gun technology confuses new shooters. With this, choosing the perfect barrel lengths for your AR became harder once again. 

The AR platform is full of debate on the topic of which barrel lengths to purchase. Everyone wants to make a point, and indeed they have. The best thing you can do is look at what perfectly fits you and prioritize it along with its tolerable downside.

ar-15 sizes

Popular Lengths

16 inches

The 16 inches length of a barrel is commonly known as a civilian standard. The ATF mandated the minimum legal length of the barrel for a gun to be 16″, and anything lower than this should secure an SBR tax stamp. 

It is famous for its general use, far bullet drop, and extreme reliability. The 16-inch barrel is stiffer than other lengths and is less affected by the barrel whip, giving high accuracy of shots. 

When combined with collapsible stock, it is compact enough, making it more convenient to use. Since it is a shorter barrel than 20″, it can give you a faster twist rate.




14.5 inches

14.5 inches is an example of a military carbine-length barrel of a gun.

Due to Federal Law, a 14.5 inches barrel can be a pain in your ass as it needs to deal with NFA paperwork and tons of regulations.

This type of short barrel needs to secure an SBR tax stamp. If you want to get away with that, you have to permanently attach the muzzle devices like a muzzle flash hider.

However, it can make it harder for you to modify it in the future.




10 inches & below

This type of barrel is built purposely for close-range fighting. Shorter barrels like this, even not of the same length, can hit targets at 300 to 400 meters only.

Just like a 14.5-inch barrel, the legality of this shortest barrel may require you not just money but effort too.

Somehow, it is very compact and easy to handle, so mobility will not be a problem. 

It may require a muzzle device for the propellant gas to counter the recoil.




20 inches & above

A 20 inches and above length of the barrel is more prolonged and heavier than other AR barrels on the market. It is built to balance longevity and muzzle velocities, just like a light sniper rifle. This length will give you a more excellent range and good performance, especially with modernized loads. 

Using this kind of barrel gives you the ease of shooting the target but never the ease of comfort when carrying it.

Though it provides balance because of the rifle length and center mass, the extra weight is a big problem, especially for a beginner.




Some Factors to Consider

Gas System

The first thing to consider when choosing the correct length for your AR barrel is the gas system. People who own guns know that the gas system is an integral part of the upper assembly. The most popular systems are the carbine and mid-length gas systems

The explosion then produces gas that will go through a gas port. When the length of the barrel increases, the gas system also increases. Too much size may cause excessive gas flow, but a gas block can help for the excessive recoil that affects the barrel life of your AR.


A common misconception in AR is that a longer barrel means more accuracy. The length of the barrel is not connected to accuracy, unlike the upper receiver. 

In accuracy testing, using a longer barrel may help you easily hit a target at a long distance, but easier is not equal to accuracy. Also, bear in mind that anything longer than supposed to be is prone to flex under stress, especially if connected in one end only. 

This problem is called barrel whip that may affect the accuracy of your shot.

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People are interested in more velocity at long ranges, so using lighter bullets is never a choice. High ballistic coefficient bullets and heavier bullets with enough velocity like nato round shoot straighter. But another way to help you avoid lower velocity is by adding length to your barrel. 

Since the gas pushes the heavy rounds for a longer duration, the bullet leaves at higher muzzle velocity. This level of speed can cause severe damage when hit. [1]  However, for extra velocity and more energy, the barrel will depend on the following: the cartridge’s capacity, the bullet weight, and the type of powder.



Shooters look forward to maximizing stability and mobility when using an assault rifle. The thing is, mobility can be a problem for AR owners with longer barrels, especially when moving to tight spots. 

It would be hard to move around in corners with a longer barrel compared to a shorter barrel. With this, mobility could be a factor to consider when choosing the length of the barrel of your pistol.

So, What's the Ideal AR-15 Barrel Length?

The ideal barrel length for AR 15 is 16 inches. It is known to give overall effectiveness and accuracy. Since a longer barrel may be hard to use, this size best fits any user, especially if you are a beginner. 

Since there is also a restriction with the length to use, 16 inches is the right choice to avoid tripping over the federal law. Choosing this will both save you money and hassle.



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