The AR15 is a versatile weapon - there are so many configurations that one can get confused about what purpose it is intended to perform. The tactical gear you add on can also get into the mix and further complicate which role it is supposed to serve.
We strongly suggest that you identify the purpose for which the weapon is going to be used before making any major modifications. The AR15 barrel is no exception - future weapon additions will be factored in with the barrel in mind, so here are a few consider to think about when choosing a barrel for your AR.
5 Points to consider on Selecting an AR15 Barrel
1. Barrel Length - The barrel length is important, and the purpose for which the weapon is going to be used will dictate the length of that barrel. For example, a short barrel is not designed to engage long range targets and will be harder to get those shots on the bull’s-eye due to reduced muzzle velocity. A short barreled AR is designed for maneuverability and easy target acquisition in shorter range situations. The best possible choice if you are going to use it for long range targets is a long barrel, perhaps as long as 20”.
2. Barrel Contours/Profile - The M4 contour is the military standard; it offers a marriage of good strength, weight and durability. The pencil barrel on the other hand is lightweight and easy to swing around but it does fall short of performance in the long run and for extended automatic fire - it just can’t stand the heat. Heavy barrels are tough and durable, able to withstand even the most heated and rugged firing conditions but they have an Achilles heel and that is their weight.
3. Barrel Twist Rate/Rifling- The kind of ammo will determine the best barrel twist rate or ratio for your AR. For most common uses that do not require long range target shooting usually have 1:7 or 1:9 ratios and these are best for shooting 55 or 62 grain bullets.
4. Chambering - The bullet is also the accompanying consideration for this. The best choice is to get a 5.56 barrel, because it will allow you to shoot both 5.56 and .223 ammo. The reverse is not recommended (don’t shoot 5.56 out of a .223 barrel). Other chambers are available for different AR setups – the most common is 308/7.62.
5. Material - The material used for the barrel must be considered as well as it can have a tactical advantage or disadvantage to you weapon. Some examples are 4140 vs 4150 steel – 4150 resists extreme heat somewhat better but commands a higher price tag. Also things like chrome lining can help with corrosion resistance if your rifle will be exposed to moisture.
These are only some of the important considerations when one is choosing an AR15 barrel. Some additional concerns might be the gas systems and muzzle devices but there are certainly others. Do your research, choose your AR barrel wisely, and pick other add-ons that would complement its purpose to make it a better performing weapon.