5.56 NATO / .223 Rem (AR-15) Barrel Length vs Velocity

By Cole Harlan, Editor·Data checked Nov 4, 2026·How we verify·Editorial standards·Corrections

5.56 NATO / .223 Rem (AR-15) velocity by barrel length

Velocity at every published length

Muzzle velocity in feet per second. Longest barrel first. A dash means not tested/published at this length.

Velocity lost per inch

This is how many fps each load loses for every inch cut off, between two lengths. Figures marked “calculated by GunReleases” are (fast velocity − slow velocity) ÷ (long length − short length) from the published points, to 1 decimal. “Tester’s stated avg” figures are the tester’s own.

Best barrel length for 5.56 NATO / .223 Rem (AR-15): the trade-offs

We don’t pick one length. Here is what the test measured in each common range, and what each choice costs.

• Under 16 in (SBR or suppressed build; NFA rules apply). At 7 in the loads measured 2135 to 2410 fps (3 of 4 loads published at this length). At 10 in the loads measured 2314 to 2767 fps. At 14 in the loads measured 2524 to 3039 fps.
• About 16 in (shortest non-NFA rifle length; 16.5 in is the published length). At 16.5 in the loads measured 2632 to 3187 fps.
• 18 to 20 in. At 18 in the loads measured 2679 to 3202 fps. At 20 in the loads measured 2740 to 3306 fps.
• 22 to 26 in. At 22 in the loads measured 2774 to 3366 fps. At 24 in the loads measured 2804 to 3409 fps. At 26 in the loads measured 2849 to 3431 fps.

• Handling: a longer barrel adds length and weight out front; a shorter one is easier to carry and swing.
• Suppressors: a suppressor adds length and weight at the muzzle, so a shorter barrel with a suppressor can end up about as long overall as a longer bare barrel. We have no velocity data with a suppressor mounted, so none is shown.

Box velocity vs measured

SAAMI’s Z299.4 (centerfire rifle) sets the test barrel for 5.56 NATO / .223 Rem (AR-15) at 24 in for rifle ballistics, measured muzzle to breech face. The 4 loads here measured 2804 to 3409 fps at 24 in.

Federal minimum barrel length

Under 27 CFR 478.11, “Short-barreled rifle. A rifle having one or more barrels less than 16 inches in length…” A short-barreled shotgun is one with barrels “less than 18 inches in length.” Those are NFA firearms. Read the rule at eCFR 27 CFR 478.11, and see our SBR rules for 2026, the state NFA checker and the suppressor buying guide. Tester barrels shorter than 16 in on this page show what velocity does, not what you may build. This is not legal advice; state law can add limits.

How this was measured

• Test setup. Remington 700 Varmint with the barrel cut down 1 in at a time from 26 in to 16.5 in; MagnetoSpeed chronograph; 5-shot averages | Same loads as the 26 in to 16.5 in series, barrel cut down from 14 in to 6 in; tester noted the 68 gr bullets tumbled from the short, slow-twist barrel.
• Our part. We copied each published number exactly. We did not average, smooth, estimate or fill in any length. A dash means the tester did not publish that length. The underlying measurements belong to the testers credited above; our compilation is CC BY 4.0.
• Limits. This is one test series with one rifle or pistol frame, one chronograph and one day’s weather. Your results will differ.
• Gap in the data. rifleshooter.com published 26 to 16.5 in and 14 to 6 in. Nothing was published for 15 or 16 in, so the chart joins 16.5 in straight to 14 in. That straight line is not a measurement. The Black Hills 68 gr load was published at even lengths only from 14 in down. The tester noted that the 68 gr bullets tumbled from the short, slow-twist barrel.

Download the data

barrel-length-velocity-5-56-223.csv has every number on this page with its source and test conditions. The combined file for all calibers and the barrel length vs velocity hub have the rest. Free to reuse under CC BY 4.0.

Frequently asked questions

Related

• Barrel length vs velocity: all calibers
• 9mm Luger barrel length vs velocity
• .380 ACP barrel length vs velocity
• .40 S&W barrel length vs velocity
• .357 SIG barrel length vs velocity
• .45 ACP barrel length vs velocity
• 10mm Auto barrel length vs velocity
• .38 Special barrel length vs velocity
• .357 Magnum barrel length vs velocity
• .44 Magnum barrel length vs velocity
• .45 Colt barrel length vs velocity
• .22 LR barrel length vs velocity
• .22 WMR (.22 Magnum) barrel length vs velocity
• .224 Valkyrie barrel length vs velocity
• 7.62x39 barrel length vs velocity
• .300 Blackout barrel length vs velocity
• .308 Win / 7.62 NATO barrel length vs velocity
• 6.5 Creedmoor barrel length vs velocity
• .243 Winchester barrel length vs velocity
• 7mm Remington Magnum barrel length vs velocity
• .300 Winchester Magnum barrel length vs velocity
• 224 Valkyrie ammo guide
• New AR-15s 2026
• Pistol brace rule 2026
• New ammo for 2026
• All GunReleases data

Sources

1. rifleshooter.com: .223 Remington / 5.56 NATO velocity vs barrel length, 26 to 16.5 in
2. rifleshooter.com: .223 Remington / 5.56mm NATO barrel length vs velocity, short barrels 6 to 14 in
3. rifleshooter.com: combined write-up, 26 in to 6 in
4. SAAMI Z299.4 (centerfire rifle)
5. eCFR: 27 CFR 478.11, definitions (short-barreled rifle)

Supplementary sources

News reports, advocacy groups, dealer practice and unofficial copies. They add context or report statements; the primary sources above control.

1. Cornell LII: 26 U.S.C. 5845, NFA definitions