# Does the length of a gun barrel have any effect on the power(?) of a bullet?

**URL:** <https://boards.straightdope.com/t/does-the-length-of-a-gun-barrel-have-any-effect-on-the-power-of-a-bullet/274244>\
**Category:** Factual Questions\
**Created:** [November 11, 2004, 7:08pm UTC](https://boards.straightdope.com/t/does-the-length-of-a-gun-barrel-have-any-effect-on-the-power-of-a-bullet/274244 "2004-11-11T19:08:51Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![Gunslinger](https://avatars.discourse-cdn.com/v4/letter/g/4491bb/32.png) [@Gunslinger](https://boards.straightdope.com/u/Gunslinger)\
**Post date:** [November 13, 2004, 11:04pm UTC](https://boards.straightdope.com/t/does-the-length-of-a-gun-barrel-have-any-effect-on-the-power-of-a-bullet/274244/21 "2004-11-13T23:04:23Z")

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One of the firearms periodicals (_Guns & Ammo_, most likely) once had an article about the effect of barrel length on muzzle velocity. They got the longest barrel they could order, chambered for a rather low-powered cartridge (.32 ACP, IIRC), and fired an bunch of shots through a chronograph while cutting the muzzle end off in one-inch increments. The conclusion was that the longer barrel made the bullets faster, up to a point at which the propellant gases stopped expanding and friction started slowing the bullet down. Optimum was somewhere around 30 inches, I think.

The optimum barrel length for a .50 BMG is really long, because it uses relatively slow-burning powder.  
There’s a theory that _shorter_ barrels are more accurate, because they’re stiffer and less likely to twist a tiny bit due to the inertial forces of the rifling. This is more prevalent among users of slow cartidges, like the .45-70, that wouldn’t gain much from a longer barrel.

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