Subject: Home produced smokeless propellants

Retrieved: 01/25/2014
Last Post: 12/03/2012

I'm curious to know if anyone has ever made their own smokeless propellents, either single base (nitrocellulose) or double base (nitrocellulose and nitroglycerine) and attempted to use them in a firearm. I know people mix up their own black powder for cannons and muzzleloading firearms, but smokeless propellants are a whole different animal, especially considering that some of the starting compounds are shock sensitive, powerful explosives. Black powder is comparatively hard to mess up.

I attempted to make my own Cordite a few days ago. As many of you may know, Cordite was a British double base smokeless propellant used extensively in rifle cartridges (namely the .303 British) and larger artillery shells. Cordite is comprised of roughly 58 parts nitroglycerine, 37 parts nitrocellulose and 5 parts petroleum jelly by mass. Acetone was used as a solvent and the mix was extruded into spaghetti like pieces, called cord powder, which led to the name of Cordite. Cordite was based off of Alfred Nobel's earlier development of Ballistite, which used camphor as a plasticizer/stabilizer. I believe this is Nobel's original patent for the stuff. I haven't been able to track down Cordite's patent yet, just the original ratios of NC, NG, and PJ.

Anyways, I weighed out the appropriate masses of nitrocellulose, nitroglycerine, and petroleum jelly. The mass totaled to just about 4 grams. The compounds were added into a small test tube. I added some toluene to thin the NG throughout the whole mix (toluene does not dissolve nearly fully nitrated guncotton). I then poured the mix into a small dish and added a few drops of acetone to dissolve the nitrocellulose and gel everything together. It was mixed thoroughly, then set to dry. As it started to harden, I tried to granulate it as much as possible with a small blade. After everything had dried, I had a small batch of about 1mm granules of Cordite. Not really cord powder, but the ratios and small grain size is all that mattered to me. I tested a few grains. It burned steadily and evenly, leaving behind a small bit of ash, but produced no smoke. I shoot firearms as a hobby, and reload my own ammunition so I have quite a stock of various powders. Some of them are double base, but I also have some triple base powders which add nitroguanidine as a flash supressor. I took a sample of commercial double base powder of the same mass and compared it to my Cordite. The burn rate was similar, even though the grains of the commercial stuff were a tad smaller and more even. The commercial powder also left behind a similar amount of black ash. Here is a video of that test.

The significant qualms I have about attempting to test homemade smokeless propellants is the quality and purity of the nitrocellulose and nitroglycerine (in particular the complete neutralization of the compounds to prevent self catalyzing decomposition) and the grain size of the final propellant. I certainly will NOT be loading my homemade Cordite into any of my ammunition, but I would be curious if homemade propellants could be tested by someone with appropriate gear, namely a way to get even grains or cords of powder and a heavy test barrel/gun. Obviously the "start small" rule of thumb would be much recommended. I'm sure loading data for the original charge of a Cordite filled shell such as the .303 British could be procured.

inspector071
8-3-2012

The primers that I use are lead styphnate, which isn't as scary as the azides. Any primers that are marked as lead free are almost always DDNP. Making the primaries seems easier than trying to fashion the shell of a primer, though. I guess that small cap of metal could be swaged in a press. I'm much more interested in testing the quality and reliability of a homemade smokeless propellent, however.

Ral123
10-3-2012

What's the problem with flash powder? Why sub-millimeter? And why depend on projectile fited quite loosely. Stuck it tight and use less propellant, that way there won't be surprises.

killswitch
12-3-2012

Another possible consideration would be the addition of polynitrostyrene in place of some or all of the petroleum jelly.

The problem with nitrocellulose, though, is the complexity of the molecule. Not all of them will contain the same quantity of monomers.

If you want to attempt something really groundbreaking, try a mixture of PETN and Tetramethylene-tetranitrosamine, with an energetic binder such as polynitrostyrene. Such a mixture would have a very long shelf life yet be extremely powerful.

Slightly off-topic, but I heard that CL-20, when used as a missile propellant, leaves behind virtually no vapor-trail. Since the molecule has hydrogen in it, wouldn't the production of steam be inevitable?