The Pros and Cons of Different AR-15 Barrel Lengths
Finding the right barrel for your new AR-15 is important. In my opinion, the barrel is one of the most important pieces of an AR-15. The biggest factors in barrel performance are materials, twist, length, and caliber. This guide will provide a thorough analysis of the pros and cons of different AR15 barrel lengths.
What factors should influence your barrel length?
Purpose
Understanding why you are purchasing a new AR-15, is the most important factor in choosing a barrel length. A home defense gun is going to be much different than a long distance precision rifle.
Just like any tool, each gun has a specific purpose. A mid-length gun can be a great fit for multiple purpose.
Ballistics
Understanding the purpose of your rifle is the first step to understanding ballistic tables.
If you goal is to shoot accurately to 100 yards, the barrel requirements are going to be significantly different than if you are trying to shoot to 700 yards.
Understanding velocity and drop is going to help you make a better decision with your barrel.
Comfort
If it’s heavy or not balanced properly, you won’t train with it. If you are not training with it, it isn’t going to preform it’s intended task.
Comfort is important because it leads to proper shooting position and increased proficiency.
A gun can be too short or too long for one person, but not another. There is no one-size-fits-all. If you have the opportunity to shoot other sized rifles before you make a decision, I would recommend it.
Caliber
The caliber of your gun plays a huge factor in your barrel choice. In my opinion, you should choose a caliber based on the barrel length and intended use. So if you know you want an super shorty for self defense that packs a punch out to 200 yards, then choose the appropriate caliber to make that happen.
However, if you know you want a long range precision rife, but also want it to be able to take down a deer at 700 yards, choose a different caliber, and therefor a different barrel length.
Legal Restrictions
If you are planning on getting a rifle with a barrel less than 16 inches, there are legal requirements to register your gun as an SBR. Make sure that you are taking that into account. It is a $200 tax stamp application through the ATF Form 1.
Short Barrel Rifle (SBR)
Technically according to the ATF (Alcohol, Tobacco, Firearms division of the government) any rifle with a barrel shorter than 16in is considered a Short Barrel Rife (SBR). These rifles will typically run a Carbine Gas System to accommodate the shorter barrel.
A SBR does require additional paperwork be filed through the ATF. You will need to fill out a Form 1 BEFORE completing your gun build, or taking possession of your rifle.
This ruling used to apply only to rifles with fixes stocks, not braces; however, on On January 13, 2023, the Attorney General signed ATF final rule 2021R-08F, “Factoring Criteria for Firearms with Attached ‘Stabilizing Braces,’” amending the language in the rule to include braces and folding stocks.
This has been a heavily debated topic and there are organizations that are trying to fight against this ruling. But as the law stands now, you must register any rifle with a barrel shorter than 16 inches.
Advantages
The biggest advantage of having a shorter barrel is maneuverability and comfort.
A 16 inch steel barrel can be heavy, and put a suppressor on the end of that, and it can be difficult to manage. However, with a short 6 inch or 10.5 inch barrel, you are able to add a suppressor and keep maneuverability.
Disadvantages
Barrels are long for a reason. It gives the bullet time to spin, stabilize, and gain velocity. Take away these things, and your rifle becomes less accurate with decreased ballistic capability.
These disadvantages can be minimized by choosing the correct caliber rifle. For instance, a 300 BLK is going to make up for some of the accuracy issues by increasing the weight of the bullet. There are lots of caliber options on the market, and some are designed to perform even with shorter barrels.
Mid-Length Barrel Rifle
There is no standard measurement for mid-length barrel. However, for me it has to relate to the gas system. A Mid-Length gas system has a 9.3 inch port. This means that it is designed for barrels 14 to 20 inches long.
The standard AR-15 barrel is 16 inches long. One reason for this is because it is the shortest possible barrel without registering as an SBR. However, it is also much more ballistically advantageous for a common .223 Remington or 5.56 NATO round.
A 16 inch barrel provides enough length for the round to reach a high enough velocity, without sacrificing 100% of your maneuverability.
This is great for someone looking for a hunting or self defense rifle. In my opinion, you can still shoot suppressed with a mid-length setup; however, it may feel a little front heavy.
Adding the suppressor even at 14.5 feels pretty balanced, but at 16 inches, I feel like the rifle is starting to get noticeably heavier.
Long Barrel Rifle
Anything over 20 inches is considered a long barreled rifle.
20 inches is probably as long as I would go with a standard .223 or 5.56 caliber rifle, but even then I would probably stick with a 16 inch barrel. This is because the increased length doesn’t provide much additional benefit out past this point, especially when compared negative aspects.
One of the only AR-15 platform calibers that would be optimised at a 20 inch barrel is the 6.5 Grendel. There may be other specialty rounds, but most platforms will not require this long of a barrel.
For AR-10 platforms such as 7.62 and .308, a 20 inch barrel is going to be the ideal ballistic barrel. These rounds are larger and have much more powder allowing them to increase their velocity even more with a longer barrel.
There are even caliber rifles such as 6.5 Creedmoor that have an optimal barrel length of 24 inches, but it is not too common.
Advantages
Every round has an ideal barrel length and twist. This ideal changes based on the weight of the bullet, but for the most part, a longer barrel is going to provide increased velocity.
Disadvantages
The biggest disadvantage of longer barrels is weight and maneuverability.
Depending on your intended use, this can be a problem. If you are doing seated long-distance shooting, then weight and maneuverability are not as important as accuracy and distance.
However, if you focus is on home defense, you likely will not be shooting anything past 100 yards. So keep that in mind.
What is the best AR-15 barrel length?
There is no one-size-fits all. There are a lot of factors when choosing a a barrel length.
However, if you are getting your first AR-15 and you are looking for an all around great rifle that can do a little of everything, I would recommend 14.5 -16 inches.
This is going to allow you to shoot suppressed and still have some mobility. However, barrel length and caliber choices are just one more reason why you need a multiple of guns in your arsenal.
Or at least thats the excuse I give my wife.
