If you buy a box of ammunition, it usually says the muzzle velocity on the box in addition to the bullet weight (or you can find the information online).

Given that bullet velocity depends on the length of the barrel, with longer barrels usually having higher velocities, and one's barrel may be longer or shorter than "standard," what is the standard barrel length that is used for calculating muzzle velocity?

1 Answer 1


The standards are set by SAAMI (Sporting Arms and Manufacturers Institute) and it depends on the type of firearm.

So if your barrel were to be shorter than the standard, one could assume that velocities would be slower than what is labeled on the box.

Of course, other factors such as temperature and or chamber sizes also apply and if you want to know your specific velocities a chronograph will be the most accurate way of finding out.

  • Shorter barrels don't always mean lower velocities. Look at handgun rounds like 45acp and 9mm in a carbine lenght barrel (16"). And for good examples of real world tests check out ballisticsbytheinch.com
    – ivanivan
    Commented Jun 19, 2019 at 13:17
  • @ivanivan Every cartridge ever made has a point where the barrel friction becomes greater than the propulsion from the gunpowder. Commented Jun 20, 2019 at 15:15

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