Thread: Energy/pressure relationship

Hori,

Try these formulae from John Barsness.
Source: http://www.riflemagazine.com/magazin...20(LO)%202.pdf
They work pretty well and are easy to set up in Excel.

1. Change in bullet weight in the same cartridge: V2/V1 = 0.5 (W1/W2 + 1)
V = velocity
W = bullet weight

2. Change in bore diameter in the same case: V2/V1 = 0.25 [(D2/D1)^2-1] + 1 (e.g. 243Win/260Rem/7mm08/308Win)
V = velocity
D = bore diameter

3. Change in case capacity, same bore size: V2/V1 = 0.25 (C2/C1 - 1) + 1
V = velocity
C = case capacity net of bullet volume

From 1, your 162 grain bullet would be going 93% of the speed of a 140 grain bullet
(e.g. 140grain = 3000fps ==> 162grain = 2796fps)