Ballistic charts are based on 24-inch barrels. I don’t have a chronograph. What is the mathematical formula to calculate the energy and velocity for shorter barrels according to the established ballistic charts? For example, in 22, 20, and 18-inch .308 calibers.
Really depends on the cartridge, but as a rough number, 25fps per inch. Also note that many velocity numbers are shown for a 26” barrel.
There’s several different YouTube channels that have done test where they measure velocity then cut the barrel down then measure again, etc. As mentioned above it’s different for every caliber, and there’s a difference between going from 24 to 22 in, versus going from 20 to 18 in.
You answer regarding velocity, but how do we calculate energy (ft/lb)?
Yes, but never for Energy (ft/lb), how do we calculate that?
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Thank you. I’ll try to figure out how to do it. I’ve never done anything like this before.
