Can't believe I found it myself
Don Miller's formula for estimating muzzle velocity for black powder cartridges.
[ From Black Powder Cartridge News, # 76, Winter 2011, pp. 27-30 ]
V = K x L1/4 x ε1/2 x ( 1 - 0.3 x ε1/2 )
V = K √ √ L √ ε ( 1 - 0.3 √ ε )
V = muzzle velocity fps
K = constant for powder used
L = barrel length in inches
ε = c/m
c = powder weight in grains
m = bullet weight in grains
Goex Fg 1418
Goex FFg 1544
Goex FFFg 1627
Swiss 1.5 Fg 1544
Swiss FFFg 1627
For a 44-40 24" barrel with 2f powder K=1544 c/m =40/200 L1/4 the hard part for those who don't like maths is 2.213. 40/200 to the power .5 = 0.447
Put this in the formula to get 1323ft/sec near enough for me.
Last edited by mikthestick; March 11, 2012 at 05:36 PM.