What is the standard barrel length used for calculating the velocity of ammunition?
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
The standards are set by SAAMI (Sporting Arms and Manufacturers Institute) and it depends on the type of firearm.
- Rimfire rifles 24 inches (page 60)
-
Centerfire rifles 24 inches with 5 exceptions (page 231),
- 7.62x39 – 20.00 inches (508.0mm)
- 30 Carbine – 20.00 inches (508.0mm)
- 300 AAC Blackout – 16.00 inches (406.4 mm)
- 350 Remington Magnum – 20.00 inches (508.0mm)
- 44 Remington Magnum – 20.00 inches (508.0mm)
Shotguns 26-32 inches (page 88-106s depends on what type of shot/slug is being tested.
Pistols depends on which cartridge is being tested (pages 141-179).
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.
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