Ah, gunpowder, the chemical substance that makes all of our fun possible. Without this critical invention much of our modern weaponry and small arms development would be non-existent. But for many people the study of this particular compound does not go very far. Your average shooter knows that you need gunpowder to send a round down range, however the history of the development of gunpowder, the differences between black and smokeless powder, types of powder, and burn rates are things that don’t frequently get touched on. Today we are going to take an in-depth look at gunpowder, its history, and more.
The Early History of Gunpowder
Gunpowder revolutionized warfare and small arms. Before its introduction ranged combat was often fought with bows and arrows (but not so much flaming arrows); defended against by plate armor, leather, or chain mail. However the spread of gunpowder weapons made these armor types obsolete. Even inaccurate, low power, smooth bore muskets could penetrate plate armor, shifting the way that armies fought wars.
While some of the largest advancements in firearms technology has come from Europe and the West at large, such as rifling, gunpowder itself was first created in Asia. In an odd twist of irony, gunpowder was the accidental invention of Taoist alchemists looking for the secret of eternal life. In 142 AD Wei Boyang wrote about a substance that would, “fly and dance”. While it is impossible to tell if he actually was referring to what we know as gunpowder, it is the only explosive that consists of three powders, making the assumption easy.
Gunpowder would eventually become more refined and the military uses would become evident. Early “hand cannons” would be developed and would spread to the rest of Asia, Europe, and the Middle East. Muskets would evolve and eventually lead to flintlock, percussion cap, and finally firearms using self contained cartridges. While today’s firearms utilize smokeless gunpowder, the early firearms, up until the 1860’s still used what we call black powder.
Black powder is a relatively simple compound, consisting of three primary ingredients, potassium nitrate (commonly called saltpeter), charcoal, and sulfur. When making gunpowder by weight these three substances are combined in a mixture of 75% potassium nitrate, 15% charcoal, and 1% sulfur. Since the first invention of gunpowder our understanding of chemistry has greatly improved, and we now have a far more complete understanding of how these chemicals react when ignited. Without getting too deep into the chemical reactions, potassium nitrate is necessary to provide the needed oxygen for the chemical reaction, as oxygen is what fuels combustion. The charcoal provides carbon necessary for the chemical reaction as well. However, sulfur is the key ingredient as it lowers the necessary temperature to create a rapid chain reaction, necessary for a firearm to work properly.
The result of the reaction of gunpowder is 43% gases. It’s these hot, rapidly expanding gases, that push the bullet down the barrel and out the muzzle. The rest of what is left behind is 56% solid material and 1% water. This creates a large cloud of smoke and would be a frequent issue for troops using such weapons, as smoke would often blind the men as they tried to see down range after firing. If you have ever seen a civil war reenactment or any semi-realistic depiction of the American Civil War you know what I am referring to. You can see YouTube historian Lindybeige talking more about the psychology and the disadvantages of muzzle loaded muskets of the time below.
Another disadvantage of black powder is the fouling it leaves behind in the barrel is hygroscopic, attracting water and corroding the barrel. For those of you, like myself, who are fond of modern muzzle loaders and reproduction cap and ball revolvers, cleaning after a range trip is a must.
However, there is an issue with sensitivity to ignition. Besides being highly flammable it can also be sensitive to sharp impacts and can be ignited by even small sparks from static electricity. To address these issues Hodgdon created an alternative, pyrodex. Pyrodex takes the base black powder and adds graphite, potassium perchlorate as well as some additional chemicals that are proprietary to Hodgdon. Another black powder substitute is Triple Seven, much like pyrodex it adds additional compounds to make the gunpowder safer to handle, however the carbon base used is from a sugar instead of charcoal. Finally there is another alternative from Western Powders Company, Blackhorn 209. Blackhorn 209 is also a safer alternative to conventional black powder, however, unlike other black powder substitutes it is not hygroscopic, so it does not corrode the barrel by attracting moisture from the air.
Loading Black Powder
Loading for black powder, or one of its alternatives, is simple and consists of simply pouring the correct amount of black powder or pyrodex down the muzzle before seating a wad and round. There are a number of various sizes of granulation for black powder ranging from Fg to FFFFg in addition to preformed pyrodex pellets that simplify the loading process.
Fg is the coarsest variety and is typically used in muzzle loaded muskets as well as black powder cannons.
FFg is a finer variety of black powder with smaller granules. It’s typically used in muzzle loaded shotguns and rifles that are .45 caliber and larger.
FFFg has even smaller granules and is suitable for black powder pistols as well as small bore muzzle loaded rifles less than .45 caliber.
FFFFg is the smallest granulation of black powder and is intended for use in flash pans on flintlock pistols and rifles.
Currently GOEX maintains loading data on a number of various black powder pistols, rifles, and shotguns. For pyrodex and triple seven Hodgdon maintains loading data as well (The link is to the Internet Archive for now as Hodgdon seems to have removed this pdf from their site). Finally for blackhorn 209, Western Powders Company keeps loading data available on its website.
One thing to note about black powder and its substitutes is that because they are generally hygroscopic and, if not kept away from moisture, they will eventually soak up enough water from the air to make the powder difficult if not impossible to ignite. This is even more of a concern in humid climates where there is even more moisture to absorb from the air. Needless to say, storing black powder in a dry place is essential. For those of you looking to go hunting with black powder firearms take note as your powder might end up too “wet” if not shot the same day.
As an aside, one of my first firearms purchases was actually a black powder rifle and I enjoy shooting them quite a bit. At this time I was working for a large sporting goods chain. I was talking with a co-worker about black powder firearms, as I had just purchased one and was going to head to the rage in a couple of days. My co-worker had spent a lot of time hunting with black powder firearms and was something of a “go to” person for information on them, so I wanted to pick his brain a bit on what powders to use. When talking with him he shared a tip about keeping your powder dry that I will probably never forget. He stated that putting a condom over the muzzle would help seal up the barrel and keep moisture out of the powder. Living in a pretty dry climate and not keeping my black powder guns loaded for any extended amount of time, I’ve never personally had a reason to test this particular “tip”. I add it here for your entertainment.
Despite being not being used by most firearms today, black powder and its substitutes still have a loyal following of enthusiasts like myself who enjoy the nostalgia and fun of black powder firearms. Modern .50 caliber muzzle loaders allow you to have some big caliber fun without a 50 BMG price tag. Now that we have gone over some of the history of black powder, let’s move on to the most recent development in gun powder, smokeless powder.
If you’d like a primer on getting into black powder firearms Iraqveteran8888 has a good primer video below.
The Development of Smokeless Powder
The early development of smokeless powder dates back to the creation of “guncotton” or nitrocellulose. This material is created by soaking cellulose from cotton or wood in nitric acid or another nitrating agent. While nitroglycerine had been around since it was first properly synthesized in 1847 by Ascanio Sobrero it was not a suitable replacement for gunpowder as it simply exploded and did not smoothly burn or deflagrate. Yet around this same time guncotton was being developed and would provide the answer that firearms designers were looking for.
Early experiments with forms of guncotton actually date back as far as 1832. That year Henri Braconnot found that when mixing starch or wood fibers and nitric acid he was able to create what he called “xyloïdine”. It was lightweight and combustible but highly unstable. In 1838 Théophile-Jules Pelouze conducted similar experiments with paper and cardboard. Pelouze would go on to teach Sobrero and Alfred Nobel but Pelouze’s “nitramidine” would also not be suitable for use in firearms.
1846 would see a further step forward in the development of smokeless gunpowder. Christian Friedrich Schönbein discovered, quite by accident, that concentrated nitric acid and cotton could be used to create a much more stable explosive. Schönbein has been working in his kitchen and spilled nitric acid. After wiping up the acid with a nearby cotton apron he set the apron on the stove door to dry. Once the apron dried it flashed and caught fire. It was from this “laboratory accident” that Schönbein developed his process that would become widely imitated.
The process called for one part of fine cotton wool to be immersed in 15 parts of an equal blend of sulfuric and nitric acids. After two minutes had passed, the cotton was taken out and washed in cold water. This was done to set the esterification level and remove all acid residue. It was then slowly dried at a temperature below 40 °C (about 100 °F). Schönbein collaborated with Frankfurt professor Rudolf Christian Böttger, who had discovered the process independently in the same year. Unfortunately, a third chemist, the Brunswick professor F. J. Otto had also produced guncotton in 1846 and was the first to publish the process, much to the dismay of Schönbein and Böttger.
However as further research would show it was the washing of the nitrated cotton that would be the key step in the process, keeping the guncotton stable. Without this key step, guncotton was liable to spontaneously catch fire and explode. It was not until this development that the production of guncotton would become safe for large-scale production.
Yet refinements were still needed and experimentation continued. Realizing the potential in 1863 Johann F. E. Schultze, a Prussian artillery captain, took out a patent on a small arms propellent made from nitrated harwood that had been impregnated with barium nitrate or saltpeter. Schultze started manufacture of the nitrated paper in Stowmarket, but the paper still had issues stemming from absorbing moisture from the air.
In 1865 Frederick Augustus Abel further refined the process and finally was able to make the process safe and workable for large-scale production. Washing and drying times for the guncotton were extended to two days, a process that was repeated eight times. The acid mixture was changed to two parts sulfuric acid to one part nitric. Despite being useful for blasting and for military use in warheads it was not until 1884 when we would see what we know as smokeless gunpowder.
Paul Vieille created what he would call Poudre B, an abbreviation of poudre blanche, or “white powder” to help differentiate it from black powder. Despite building on experiments done previously, Vieille’s 1884 invention would change things dramatically. The new “white powder” was made from 68.2% insoluble nitrocellulose (containing more than 13% nitrogen), 29.8% soluble nitrocellulose that was gelatinized with ether and 2% paraffin. The result would be pressed into thin sheets by rollers and then cut into flakes. The result was a gunpowder that would not detonate unless compressed, making handling safer. The first initial benefit that militaries saw over black powder was storage. Smokeless powder could burn when wet, eliminating the difficult matter of storing black powder. Furthermore it gave off far less smoke, hence the name, smokeless powder. Because it was also three times more powerful than black powder it could provide higher muzzle velocities, flatter trajectories, and longer ranges than black powder firearms. The first firearm to utilize this new smokeless powder was the Lebel Model 1886 rifle.
Other countries would soon adopt the formula and the way that small arms performed was forever changed. Long range bolt actions, followed soon by semi-automatic and full automatic firearms would be created within the following decades. Today we are still using the same basic type of gunpowder in our handguns and rifles. However during the more than a century since it was first created, smokeless powder has seen additional refinements and improvements.
Composition of Smokeless Powder
There are a number of types of smokeless powder that can be broken up into different categories based on composition and physical characteristics. There are also various burn rates as well however I will touch on them later.
When talking about composition there are three main types of smokeless powder. Single base, double base, and triple base.
Single base powders use nitrocellulose as the only propellent in them. This is typically a ether-alcohol colloid of nitrocellulose which John B. Bernadou a, lieutenant United States Navy, filled for a patent on in 1901. Single base powders typically have a detonation velocity of 7,300 m/s and are one of the two types of compositions readily available to reloaders.
Double base powders take the nitrocellulose and add nitroglycerin. It’s the combination of these two propellants that give double base powders their name. With the addition of nitroglycerine a double base powder has a slightly greater detonation velocity of 7,700 m/s when compared to single base powders. Double base powders are also readily available to reloaders on the market today.
Finally there are also triple base powders. These use nitrocellulose and nitroglycerine as well. However, they also contain nitroguanidine. The nitroguanidine is added into the solvent mixture as the smokeless gunpowder is made, but it does not dissolve into the other materials. Triple base powders are typically only seen in very large-caliber guns such as artillery and the main cannon on tanks.
Smokeless powder that we see today will typically be made up of the following components as well. A deterrent to slow the burn rate, one or more stabilizers to improve the shelf life of the smokeless powder, one or more decoppering agents, some kind of flash reducer, as well as other additives to reduce wear on the barrel.
Despite having touched on nitrocellulose, nitroglycerine, and nitroguanidine, there are other propellants used in modern smokeless powders. These include, DINA or bis-nitroxyethylnitramine, Fivonite also called tetramethylolcyclopentanone tetranitrate, DGN or di-ethylene glycol dinitrate, and finally Acetyl cellulose.
Deterrents, as previously mentioned, are used in smokeless powder to slow the burn rate of the powder. The burn rate of a powder is important to provide uniform pressure on the bullet as it moves through the barrel. Some of the most common deterrents used in smokeless gunpowder include Centralites, Dibutyl phthalate, Dinitrotoluene however this is highly toxic and has been replaced with other chemicals in modern powders, Akardite, ortho-tolyl urethane, Polyester adipate, and Camphor but this is also no longer used as a deterrent in smokeless gunpowder.
Stabilizers help to slow the decay of the propellants into other chemicals. The ones that are commonly used are Diphenylamine, Petroleum jelly, Calcium carbonate, Magnesium oxide, Sodium bicarbonate, and beta-naphthol methyl ether. In the past Amyl alcohol and Aniline have both been used as stabilizers, however both are considered to be obsolete.
Decoppering agents are added to smokeless powder to help prevent the buildup of copper in the lands and grooves of the barrel. Tin metal and tin based compounds such as tin dioxide as well as lead have been used. However, lead is no longer used due to toxicity concerns. The most favored decoppering agent used is bismuth and bismuth compounds such as bismuth trioxide, bismuth subcarbonate, bismuth nitrate, bismuth antimonide. The reason for this is that copper will dissolve into molten bismuth compounds and form a brittle alloy that can be more easily removed from the barrel.
Of particular note for those who may be reloading ammo for home defense are flash suppressors. These compounds, when added to smokeless gunpowder help to reduce the brightness of the flash at the expense of increasing the amount of smoke produced. These compounds include Potassium chloride, Potassium nitrate, Potassium sulfate and Potassium hydrogen tartarate. Potassium hydrogen tartarate is actually a byproduct of wine production and was used, naturally, by the French artillery.
Other elements are also added to smokeless powder to help reduce wear on the barrel, these include Wax, Talc, and Titanium dioxide. Polyurethane has also been used as well as a jacket over the powder bags in large guns.
A number of other additives are also used in smokeless powder. Graphite is commonly used to keep the powder from clumping as well as to help dissipate static electricity. Rosin is used in ball powder to help keep the small spheres together. Finally Ethyl acetate is also used in the production of ball powder.
Physical Structure of Smokeless Powder
As far as the physical structure of smokeless powder goes, there are again three different kinds. Flake powder is formed into small discs during the manufacturing process. Ball smokeless powder is, naturally ball-shaped and is formed into small spheres. Extruded or rod smokeless gunpowder is normally formed into small cylinders. However filaments may also be used as well in some applications.
The physical structure of smokeless powder has the greatest effect on the burn rate of the powder. Simply put the more area of each individual granule of smokeless powder has to burn, the faster it will burn. As a rule of thumb ball powders will burn the fastest, followed by flake, and then extruded powders. The burn rate is important, especially between rifles and pistols. You want a slow burning charge that continues to smoothly burn as the bullet travels down the barrel of the rifle to take advantage of the long barrel. Conversely fast burning powders are best for pistols that have far shorter barrels. Since this is a post about gunpowder specifically I won’t go into too much of the details of reloading. An in-depth post on reloading and getting started will come at a later date.
So, as a rule of thumb, as the capacity of a case increases the desired burn rate goes down.
When reloading you are looking to get the maximum loading density that achieves the highest velocity without going over the maximum average pressure (MAP). Loads that fill almost the entire case or overfill it at no more than 5% compression, while achieving near maximum MAP, are considered the most efficient loads.
Now, here’s where a burn rate chart can help you. If you are currently working with a loading that you would like to improve upon, be it accuracy, velocity, ect. A burn rate chart can help you find other powders that have a similar burn rate to what you are currently using. However never take this to mean you can just replace the powder you are using with a “similar” one and use the same charges. You will need to start with a lower charge and work up from there. Never assume that one powder can simply be substituted for another. If you are looking for burn rate charts there are a number out there that you can choose from. Many popular reloading manuals feature them as well as online ones from Hodgdon, Accurate Powder, and Reloaders Nest.
Another element of burn rates to take into consideration is outside temperatures. Many of the famous African big game hunting cartridges from Britain are loaded at comparatively low pressures despite having massive cases. When these cases heat up under the hot african sun they begin to operate at higher pressures, so they are loaded with this overhead in mind. Getting the action stuck in the middle of trying to take down a pissed off African game animal is not something anyone wants to deal with. If you are reloading for hunting in a hot climate take this into consideration.
Gunpowder, be it black or smokeless powder, has truly changed the way we hunt, defend ourselves, and more. Hopefully this little article helped to inform you more about the history and development of one of the key things that lets us have fun at the range. As a final note I will issue one oft-repeated warning that bears repeating. Never, ever mix up smokeless and black powder, otherwise you will at best end up on a gun blooper reel on YouTube. If you want some video evidence as to why look below.
Update 1/17/2017: Hodgdon has removed the Pyrodex and Triple Seven load data from their site; switched URL to archived version