How to determine which AR15 barrel length is best for you

Apr 6th 2022

Which barrel length option is right for your AR15?

When choosing the right barrel for your AR15 build your first determination should be what practical use you will be using the rifle for? Will this rifle be a bench queen and only be used for shooting tiny groups at the range or will I be using this rifle for tactical training and general defensive purposes?

The barrel and optic of any rifle are the ultimate determining factors of its ballistic performance and capability, it is the difference between a CQB or a RECCE build. A rifles barrel length will also determine its maximum effective range for the given caliber of choice. Below we will show some various muzzle velocities pertaining to barrel lengths, the following data was sourced using a bolt action chambered in .223 Remington and using Federal XM193 55gr ammunition.

Barrel Length   

Muzzle Velocity in FPS

   Standard Deviation

26”

3431

21

25”

3426

31

24”

3409

39

23”

3350

19

22”

3366

42

21”

3305

47

20”

3306

24

19”

3259

39

18”

3202

25

17”

3151

16

16.5”

3187

44

14”

3039

19

13”

2974

16

12”

2919

32

11”

2834

19

10”

2767

10

Now let us take a look at overall lengths with the given barrel lengths. Overall length of your rifle should be the largest factor to come into question when sourcing your AR15 barrel. The maneuverability of any given individual and rifle combination will determine just how efficient that person can be when moving in and around various obstacles. The individual's height can also play a role in just how efficient the individual can move while having the rifle in a slinged position, if you are a shorter person than it would become cumbersome to sling and move with a rifle with a long overall length, not to mention adding a silencer to the end of it and adding even more rife length to overcome.

The following data provided is taken from an AR15 with a Magpul ACS Rifle stock and 6-Position Carbine Length Receiver extension. We listed data for standard barrel length options available in the market. Note that receiver extension systems and stock options will vary in the length which will not be reflected in the data provided.

Barrel Length

Stock Collapsed

Stock Extended

26”

42.5”

45.5”

24”

40.5”

43.5”

22”

38.5”

41.5”

20”

36.5”

39.5”

18”

34.5”

37.5”

16”

32.5”

35.5”

14.5”

31.0”

34.0”

13.7”

30.2”

33.2”

12.5”

29.0”

32.0”

11.3”

27.8”

30.8”

10.5”

27.0”

30.0”

8”

24.5”

27.5”

What we can extrapolate from this data set is which overall length goal is needed for the most efficient and comfortable setup for any given individual’s needs based on the person's body height relevant to the rifle’s overall length when in a slinged position.

In conclusion there are many factors to consider for which barrel length option is the best fit for the end goal of the rifle. We hope that the data provided can help with your decision-making process so that you can build a rifle that is best suited for your individual requirements.