I got to wondering where the air come from in ammo. Many cartridges are loaded compressed so the only air is in the small spaces between the powder grains. It seem to me that the air spaces are much smaller volume than power but more air than fuel is usually required for something to burn. So how does this work with gunpowder??
Gunpowder combustion question
- Thread starter BruM
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WardenWolf
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I believe the powder may already have oxygen as part of its makeup. Regardless, the primer also creates a compression scenario, which works much like a diesel engine (increased pressure = better combustion). Free gunpowder will burn. Contained gunpowder (as in a cartridge or powder keg) explodes.
The Bushmaster
Member
Gun powder generates its own oxygen...Does not need outside air...
That is correct, explosives in general already contain everything they need, chemically, in order to create a violently fast reaction, although many do also need containment in order to explode rather than burn (including nuclear weapons, even though they are not chemical in nature).
Well, in the case of gunpowder (black or smokeless), a large amount of oxygen is still needed and is locked in the chemicals until it is released; it usually comprises most of the explosive material, actually, such as the case of potassium nitrate in black powder. While the primer contributes some pressure of its own, its main function is to ignite or detonate the main charge of powder, of course, which then builds its own pressure within the confines of the cartridge case (temporarily plugged by the bullet).
In analogy, the primer is more like the spark plug of a gasoline internal combustion engine than it is any part of a diesel engine, and in addition the propellant is already pre-compressed in solid form with its own oxygen inside a small container rather than actively compressed as a mixture of fuel and oxygen from the air.
Yes, when it's contained pressure is allowed to build, which in turn speeds burning, resulting in a lot of pressure escaping very quickly (i.e. an explosion), pushing the bullet out at high velocity during the process. This has little to do with the primer creating compression, however.
Cap'n Jack Burntbeard
Member
The action is not a burning (oxidizing) action, it is an explosive decomposition of the stabilized nitrocellulose in the powder.
http://en.wikipedia.org/wiki/Smokeless_powder
http://en.wikipedia.org/wiki/Explosive_material
http://en.wikipedia.org/wiki/Smokeless_powder
http://en.wikipedia.org/wiki/Explosive_material
Oh, right, I momentarily forgot what smokeless powder was based on.
What I said about oxygen specifically applies only to black powder, then; it was just an example, as there are many kinds of explosives.pikid89
Member
well why does the powder in my 270 ammo sound like its only half full...it seems that if i were to shoot at somthing with any level of declination to the gun, than the powder wouldnt even be contacting the primer
The powder doesn't have to be in intimate contact with the primer. The flash from the primer easily fills the case, igniting the powder.
If you reload, try firing a primed case sometime. I'd be surprised if you don't see some flash exiting the muzzle.
Officers'Wife
Member
You have to remember that smokeless powders are essentially forms of dynamite as they contain nitroglycerin. As such they do not burn when subjected to shock, they detonate i.e. energy held within relatively weak chemical bonds is released by the breaking down of those bonds. Oxygen is not a factor in the detonation even though oxygen may be present in the molecule.
Cap'n Jack Burntbeard
Member
^^^^
Precisely!
Precisely!
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