Thinking a little more about energy with BP, it occurred to me that a given weight of BP will release a reasonably predictable amount of energy when fired. I know that BPs are not all the same, but chemically they are very similar and the same chemistry and physics will apply. Could this help us to estimate how to stay within the OPs range limits?

So, I discover that 1 kg of BP contains about 3MJ of energy, which is 2.2M ft-lbs.

Quick calculation shows this to be just about 143 ft-lbs per grain.

Much more than I was expecting!


...and not at all helpful.

Clearly firearms are a very inefficient way of converting BP chemical energy into projectile kinetic energy.

Another approach is needed.