Quote Originally Posted by enfield2band View Post
I don't disagree with what you are saying. I think we are looking at this differently.

I have read somewhere that the detonation velocity of blackpowder is about 950fps. Thus explosives are,as far as I am aware, determined by their detonation velocity. SEMTEX has a detontaion velocity of 5 mile per second, which is why I used the term detonation. Blackpowder changes from a solid to a gas when ignited even when unconfined. As you know smokeless does not, it burns very rapidly.
The deflagration velocity of BP is about what you have stated. This is subsonic even in air and far less than the speed of sound in solids - while it is believed possible to detonate BP it is extremely difficult to do so and certainly not in the conditions encountered in a firearm. Even initiation of BP using a detonating booster (i.e one which produces a supersonic shockwave) is unlikely to detonate the BP itself and attempts to do so have been inconclusive. BP DOES NOT HAVE A RECOGNISED DETONATION VELOCITY (for that matter neither does smokeless).

Smokeless also changes from a solid into gasses when ignited, even unconfined. What did you think it does? Smokeless at or about atmospheric pressures burns (deflagrates) quite slowly, whereas BP burns much faster at atmospheric pressures, but the burn rate increases much more slowly as pressure increases (in fact practically linearly) whereas the deflagration rate for smokeless increases exponentially with increasing pressure.