5.56 Velocity by Barrel Length

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Velocity by barrel length for 5.56x45mm NATO cartridge. Information is from multiple sources including RifleShooter.com and Sonoran Desert Institute. We'll also discuss best barrel length for something like an AR-15 pistol as well as "SPR" / DMR-type setup below, to help you to better navigate various typical barrel length offerings.

We'll also include velocity data for .223 Remington below, for easier access without needing to leave the page.

Barrel Length Federal XM193 (55 gr. FMJ) Winchester M855 (62 gr. Penetrator)
26" 3431 fps 3280 fps
25" 3426 fps 3229 fps
24" 3409 fps 3188 fps
23" 3350 fps 3169 fps
22" 3366 fps 3158 fps
21" 3305 fps 3117 fps
20" 3306 fps 3097 fps
19" 3259 fps 3060 fps
18" 3202 fps 3052 fps
17" 3151 fps 2972 fps
16.5" 3187 fps 2992 fps
14" 3039 fps 2808 fps
13" 2974 fps 2694 fps
12" 2919 fps 2646 fps
11" 2834 fps 2579 fps
10" 2767 fps 2489 fps
9" 2662 fps 2403 fps
8" 2520 fps 2296 fps
7" 2410 fps 2135 fps
6" 2202 fps 1955 fps

.223 Remington Velocity by Barrel Length

For easy access for those looking, we've included velocity data for .223 Remington on this page as well. Data for Black Hills 68 gr. and Remington UMC 55 gr. FMJ are from RifleShooter.com. The velocity data for Remington UMC 45 gr. and 50 gr. JHP's are sourced from Ballistics By The Inch.

Barrel Length Black Hills 68 gr. Match Remington UMC 55 gr. FMJ Remington UMC 50 gr. JHP Remington UMC 45 gr. JHP
26" 2849 fps 3182 fps -- --
25" 2828 fps 3221 fps -- --
24" 2804 fps 3211 fps -- --
23" 2775 fps 3131 fps -- --
22" 2774 fps 3111 fps -- --
21" 2762 fps 3090 fps -- --
20" 2740 fps 3071 fps -- --
19" 2699 fps 3028 fps -- --
18" 2679 fps 3006 fps 3179 fps 3354 fps
17" 2652 fps 2922 fps -- --
16.5" 2632 fps 2968 fps -- --
16" -- -- 3076 fps 3257 fps
14" 2524 fps 2808 fps 2901 fps 3099 fps
13" -- 2694 fps -- --
12" 2424 fps 2646 fps 2964 fps 2943 fps
11" -- 2579 fps -- --
10" 2314 fps 2489 fps 2682 fps 2776 fps
9" -- 2403 fps -- --
8" 2121 fps 2296 fps 2478 fps 2536 fps
7" -- 2135 fps -- --
6" 1865 fps 1955 fps 2153 fps 2189 fps
5" -- -- 1921 fps 1939 fps
4" -- -- 1674 fps 1709 fps
3" -- -- 1276 fps 1277 fps

Best Barrel Length For 5.56 NATO

For Subsonic Loads

Based on the data above, it appears that for subsonic loads such as 220 grain (where the .300 BLK really shines), barrel length can be an afterthought, particularly if you plan on using a suppressor. Something like a 7.5" barrel with an appropriate 7 to 8 inch suppressor would allow for a package that is still shorter and a little handier than a typical 16" barrel setup. Keep in mind that many manufacturers will not warranty their suppressors on barrels shorter than around 7.5 inches. This would still make a handy setup for military and law enforcement applications, as well as home defense or just a fun recreational setup for novelty.

For Maximum Velocity

For maximum velocity with 5.56x45mm NATO, a 20-inch barrel will give the most velocity possible out of a common barrel length rifle. For best accuracy, a heavy / bull barrel is preferred. Theoretically, a 22-inch barrel would be the best combination between somewhat manageable maneuverability and maximum velocity, but it's a non-standard length. Anything longer is even more non-standard, and has diminishing returns, though still does offer velocity advantage. But excessive barrel lengths like this should probably only ever be considered if you plan on shooting at 1,000 yards with a dedicated benchrest setup, which is also uncommon. For most applications, an 18" heavy barrel will still offer velocity advantage over a typical 16" barrel and plenty of accuracy. Consider that this is the basic setup of the U.S. military's former Mk 12 Mod 0 "SPR" (Special Purpose Rifle), which was said to have an effective range up to 700 meters.

Note: If you're looking for absolute maximum range from something like an AR-15 platform, it may be worth considering cartridges like the 6.5 Grendel, .224 Valkyrie, and others. The 6mm ARC seems to have impressive potential from our understanding. Also consider the lesser-known .277 Wolverine, which is a bridge between the .223/5.56 and .300 Blackout, and uses the same .223/5.56 cases to load with.

Best Overall Barrel Length for 5.56 NATO

Best barrel length for 5.56mm (and .223 Remington) depends on your use case. For an overall great rifle, there's nothing wrong with the most popular barrel length of 16 inches. It doesn't have any major disadvantages in velocity and is still overall quite maneuverable. For a pistol or SBR setup, if trying to maintain decent velocity and meneurverability, anything less than a barrel in the 10-inch range seems like a hard sell because velocity begins to drop heavily. When using a silencer / suppressor, also be sure to keep in mind that many manufacturers have a minimum barrel length for requirement for their warranties, which is often (but not always) about 10 inches or above in the case of common 5.56mm suppressors. Also consider that longer barrels will work better with a suppressor. As a result, most who want a suppressor may want to opt for a barrel in the 10 inch range, which works out if you want a pistol-type setup for use with and without a suppressor. Since many silencers are in the 6" to 7" range, this gives a similar length to a typical 16" barrel AR-15, and also give some velocity advantage over an unsuppressed 10 inch barrel.

Other Information

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