Home produced smokeless propellants

Retrieved: 12/19/2014
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 US456508.pdf 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.

killswitch
8-3-2012

The bigger problem for the home firearms enthusiast would be the primer. Lead azide is much more dangerous to handle than nitrocellulose.

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.

quicksilver
9-3-2012

Where exactly is this thread going?

Bring a smokeless propellant to the general public takes several years of research by professionals with decades of experience. Manufacturing a smokeless propellant by a Graduate-level student would likely involve several hundreds of thousands of dollars of testing equipment. Even at that point, it's a damn poor idea.

Using black powder / ammnio pulver as a substitute and devising a consistent "flame route" primer might be possible for an individual with a great deal of patience - however, those primers need to be micro-gram consistent. And although I agree with Killswitch here, I don't see this thread coinciding with Forum Rules. It is also edging close to the "practical-use issue".

Therefore if someone wants to interject some science here; fine. If not, let's leave home-made Smokeless Powder to people who have been working with burn ratios and initiation / burst-strength elements for decades.

_________________

If you hand-load for a hobby, that is miles away from the energetic chemistry needed to mfg a propellant. Listed would be the chemistry agenda of each element, their experimental issues of time, means, math, initiation structure, propulsion modeling (& it's agenda). It is no small thing to tame a high explosive to become a propellant. It takes an enormous amount of study and research that is documented on a continuum so as to find pathways to burning formats rather than detonation formats.

If you have been hand-loading for any time now you know that TOO LITTLE powder can result in a catastrophic explosion of a firearm just as too much or a blunder of burning patterns. The deflagration issues mapped in a mathematical model of cresting pressure vs. resistance of the projectile needs to be outlined PRIOR to the development of the propellant itself. This is no small task. The polymers in Smokeless Powder are burning rate modifiers. Understanding how burning rate modifiers function in a High Explosive brought to a propellant has been under study for the entire history of smokeless powder.

The level of genuine science involved in energetic materials is voluminous. The overwhelming majority of people involved in this area of interest would love to see it risen an order of magnitude, rather than maintained at an entry level. We have several people here who have not posted in quite some time and frankly, I would like to see that change.

We DO have some Forum members with a science background in depth enough to map out some of these details but they are not simplistic by any means. That is why some successful powders have remained on the market for decades in both canister and bulk sales. Military demands for TBSP have even more complexities which would take several pages to even introduce.

This is a very interesting subject. I would love to see some modeling and details.

niertap
9-3-2012

You might consider side stepping the primer issue by adding a small amount of #0000 steel wool to the propellant and just using a 9v battery or a couple AA batteries. I always make my E-matches that way. Whistle mix being the pyrotechnic in the E-match.

Black powder isn't terribly high pressure, but I would still have the projectile fit quite loosely. I would never feel confident enough to shoot a snugly fitting bullet out of a home-made gun, without concrete in-between.

Slightly off topic, but the chamber pressure of different things like benzolift, smokeless, black powder, & whistle mix might be interesting. Haha I suppose flash powder could even be used, so long as the barrel is sub- millimeter.

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 wont 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?