Powder correlation

[Ezra]

You guys know how some folks like to use 2f versus 3f and so on?  Is there any formula, calculation or chart that can reasonably correlate x amount of 3f is equal to y amount of 2f?  Just curious.

Ez

[pathfinder]

If going from 2f to 3f,use a bit less. If going from 3f to 2f,use a bit more.

[smokinbuck]

Ezra,
I agree with Pathfinder. I've always heard that the difference should be +/- 10%.
Mark

[hanshi]

While the formula makes sense, barrels are such individualists that they seldom adhere to formulas.  I know of some short barrels that give equivalent velocities to longer ones or even exceed them.  Some barrels will flip flop giving the speed edge to 2F.  Every shooter needs a chronograph.  I've had one since the last century and it really opened my eyes.