These statements was made in the thread entitled
Clips vs Magazines, bullets and other terminology.:
Usually when smokeless powders are ignited (when unconfined), they just burn.
When they are confined, however, they produce large volumes of gas, this can cause the container they are in to rupture, in effect producing an explosion.
and
Smokeless in a confined burn can explode.
You'll note that I cited some smokeless propellant burns (cordite) with regard to the destructions of ships to illustrate the power of burning smokeless powder. While researching another off line conversation related to this thread:
WW2 "What if?" regarding the destruction of HMS Hood, I have been looking for a good, concise description of smokeless powder's burning characteristics. Happily enough, I found one in a SAAMI brochure on like which states:
When smokeless powder burns, a great deal of gas at high temperature is formed. If the powder is confined, this gas will create pressure in the surrounding structure. The rate of gas generation is such, however, that the pressure can be kept at a low level if suffi- cient space is available or if the gas can escape.
In this respect smokeless powder differs from blasting agents or high explosives such as dynamite or blasting gelatin, although powder may contain chemical ingredients common to both of these products.
Smokeless powder does not detonate like high explosives as it has a controlled rate of burn and differs considerably in its burning characteristics from common “black powder.” Black powder burns at essentially the same rate out in the open (unconfined) as when in a gun.
When ignited in an unconfined state, smokeless powder burns inefficiently with an orange-colored flame. It may produce a considerable amount of light brown, noxious smelling smoke. It leaves a residue of ash and partially burned powder. The flame is hot enough to cause severe burns.
When it burns under pressure, as in a cartridge fired in a gun, smokeless powder produces very little smoke, a small glow and leaves very little or no residue. The burning rate of smokeless powder increases with increased pressure. (emphasis mine)
If burning smokeless powder is confined, gas pressure will rise and eventually can cause the container to burst. Under such circumstances, the bursting of a strong container creates effects similar to an explosion.
You can find the whole brochure here, if you are interested:
http://www.saami.org/specifications_and ... Powder.pdf
