[Big Friend Ten (BFT)]

For Greg's question of what causes "detonation" in a barrel:

From a US Army Technical Manual:

b. Deflagration. If a particle of an explosive reaches a temperature at which the rate of decomposition becomes significant, deflagration or spattering of the particles from the surface occur prior to decomposition. At a characteristic temperature, heat output is sufficient for the reaction to proceed and be accelerated without input of heat from another source. At this temperature, called the ignition temperature, deflagration, a surface phenomenon, begins. Gaseous reaction products flow away from the unreacted material below the surface. Deflagration of all the particles in a mass of finely divided explosive occurs almost simultaneously. In a confined space, pressure increases, which, in turn has the effect of increasing the rate of reaction and temperature. The final effect of deflagration under confinement is explosion, which may be violent deflagration or even detonation. In the case of low explosives, such as loose black powder and pyrotechnic compositions, only violent deflagration can take place. Nitrocellulose propellants (smokeless powders) can burn, or if confinement is sufficient, deflagrate so rapidly as to detonate.