Quote Originally Posted by Turnup View Post
I was hoping to put an upper bound on the energy of a projectile from a given weight of BP. The amount of energy in BP is not dependent upon its grain size.

The maths are correct, unfortunately the (in)efficiency of realising that energy makes the number useless.

The rate of deflagration is admittedly different for different granularities and is also dependent upon the peak pressures achieved - the chemical energy contained therein is a constant by weight.
If your posit is correct, why then do we get more velocity out of a given weight of Swiss powder than we do for the same granulation of non-Swiss powder? Can it be simply because the Swiss use willow charcoal and British makers don't?

There are way too many vagaries in BP shooting - the amount, or lack of, compression of the charge, the bore-wear, bullet windage, temperature, humidity and so on.

tac