.300 Winchester Magnum Barrel Length vs Velocity

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

.300 Winchester Magnum 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 .300 Winchester Magnum: 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 (NFA rules apply). This test did not go below 16.25 in, so there is no measurement here.
• About 16 in (shortest non-NFA rifle length; 16.25 in is the published length). At 16.25 in the load measured 2575 fps.
• 18 to 20 in (18.25 and 20.25 in are the published lengths). At 18.25 in the load measured 2696 fps. At 20.25 in the load measured 2752 fps.
• 22 to 24 in (22.25 and 24.25 in are the published lengths). At 22.25 in the load measured 2786 fps. At 24.25 in the load measured 2892 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 .300 Winchester Magnum at 24 in for rifle ballistics, measured muzzle to breech face.

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 magnum action with a Shilen #8 contour 1:10 in chrome-moly barrel cut down 1 in at a time from 24.25 in to 16.25 in with a reciprocating saw and then a hacksaw, crown not re-cut; MagnetoSpeed V2 chronograph; 5 shots per length; about 55 F in heavy rain; one factory load.
• 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.
• One load. rifleshooter.com tested one factory load, Federal Gold Medal 190 gr Sierra MatchKing, so this page has a single line. The barrel was cut with a reciprocating saw and a hacksaw at the range and the crown was not re-cut.

Download the data

barrel-length-velocity-300-win-mag.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
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• .357 SIG barrel length vs velocity
• .45 ACP barrel length vs velocity
• 10mm Auto barrel length vs velocity
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• 5.56 NATO / .223 Rem (AR-15) barrel length vs velocity
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• .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 Win Mag ammo 2026
• New ammo for 2026
• All GunReleases data

Sources

1. rifleshooter.com: .300 Winchester Magnum, how barrel length changes velocity (24.25 to 16.25 in)
2. SAAMI Z299.4 (centerfire rifle)
3. 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