Ammunition

The Evolution of Modern Ammunition

20 different caliber handgun cartridges

The firearms enthusiasts of today are really lucky because we are living in the golden age of ammunition. When I started shooting in the 1950s not as much was known about what constituted good, accurate, and ballistically efficient ammunition. Today, we have the benefit of all the pioneers who advanced the science and manufacturing techniques that give us the great products we all enjoy. To understand what I mean, let us look at some of the history that we take for granted today.

The Metallic Cartridge

For modern firearms to operate successfully, they require three traits in the ammunition used. The first and most obvious requirement is that it must be totally self-contained in what is called, “a fixed charge.” To qualify, each cartridge or round must contain, a primer, propelling charge, projectile or projectiles, and a case to hold them all together. Next, the case must be made of a ductile metal that, when fired, will expand against the walls of the firearm chamber sealing it so as to prevent the expanding gas from blowing back along the sides of the case.

three different .22 caliber cartridges
The .22 caliber cartridge has been offered in a variety of different sizes and configurations.

Those walls must then immediately contract after the gas pressure drops so that extraction of the spent case may be accomplished. Finally, its ignition system or primer must be completely self-contained. That is accomplished by having a built-in mechanical anvil to allow the firing pin blow to crush and combine the components and detonate the priming charge.

It only took about 800 years to get from black powder spewing objects out of bamboo tubes to the self-contained cartridge. Technology took its time developing everything necessary to make a totally self-contained metallic cartridge. The last piece of the puzzle was the ductile metal that could contain everything. There is no question that the first truly practical application of the components to create a repeating metallic cartridge was the .22 Rimfire development by Horace Smith and Daniel B. Wesson in 1857.

The .22 Rimfire in its most recognizable form is the cartridge we are all familiar with that has the primer compound in the rim of the cartridge case head. Rimfire cartridges were developed during the black powder era as were the first centerfire cartridges. But it was the development of the centerfire cartridge that permitted the design of modern high-velocity firearms that did not appear until much later. However, ammunition did not really reach its true potential until the invention of Smokeless Powder.

The centerfire cartridge was invented by Monsieur Clement Pottet of Gay Paree with subsequent improvements made by Monsieur Francois E. Schneider, also of Paris. In 1861, the centerfire cartridge was introduced in England by Mr. George H. Daw who owned a rifle manufacturing company and bought the English patent rights from Monsieur Schneider.

As it played out, Mr. Daw lost the patent rights in a case brought on by the Eley Brothers — who were at that time rival manufacturers of cartridges and pocket revolvers. The award of the patent to the Ely Brothers was made possible because the patent was not kept in force in France, where the invention was originally recorded. After that, centerfire cartridges quickly began to replace rimfire cartridges in applications where higher pressures were required. Today, of course, centerfire cartridges are the most common ammunition type in use and are currently used in most modern firearms.

cutaway illustration of a .22 caliber rimfire cartridge
A cutaway illustration of a .22 caliber rimfire cartridge.

In a centerfire cartridge, there is a small cap in the center of the cartridge, which contains two compounds separated by a thin foil membrane. The rest of the cartridge case is filled with gunpowder. There is a bullet held in place at the other end.

To fire, the primer must be struck with a sharp blow. When the firing pin or hammer crushes the cup, it causes the foil to rupture and the compounds combine. The resulting chemical reaction causes an explosion which in turn ignites the main charge. The expanding gases from the burning propellant force the projectile down and out the barrel to its target. Let’s look at the invention of the center fire primer and how it came to be.

In 1866 an American, one Hiram Berdan patented a centerfire priming system. In his system, the cartridge has a small bump in the bottom of the case that is called the “anvil.” The priming mixture is placed in a small metal cup that is placed on top of the anvil and sits flush with the base of the cartridge. When the hammer (or firing pin) hits the metal cup, it crushes the primer into the anvil and detonates it. There are 2 vent holes in the case that allow the flash of the primer to ignite the main charge in the body of the case.

Top illustration view of a cartridge primer and section of primer
Top view primer and section of primer.

The other centerfire priming system was invented by Colonel Boxer and was also patented in 1866 but this version was in the United Kingdom. The Boxer principle is similar to the Berdan system, except the anvil is not part of the cartridge case. Instead, the anvil sits at the top of the primer cup and the cartridge case has one hole in the center.

Ironically, the Berdan system invented by Hiram Berdan, an American, is used in Europe, and the Boxer system invented by Colonel Boxer, an Englishman, is used in the U.S. Conveniently, centerfire weapons can fire cartridges using either system — so long as the cartridge sizes are correct.

Illustration of a section of the base of a centerfire boxer primed shell or cartridge
A section of the base of a centerfire boxer primed shell or cartridge.

Smokeless Propellant

The next part of the puzzle was the development of smokeless powder. It must be understood that since the time of the Napoleonic Wars, military commanders had been complaining about the problems of observing the battlefield and giving orders while it was covered in thick smoke from the black powder being used. A major development occurred in 1886 when Paul Vieille invented a smokeless gunpowder called Poudre B. It was made from gelatinized guncotton mixed with ether and alcohol that was passed through rollers and formed into thin sheets, which were then cut into flakes. A revolutionary feature of that propellant was that it would not burn unless it was compressed, which made it very safe to handle under most conditions.

Vieille’s powder improved the effectiveness of small arms in the following ways:

  1. It was a propellant not an explosive.
  2. It gave off almost no smoke.
  3. It was three times more powerful than black powder.

That last feature gave it a higher muzzle velocity which meant a flatter trajectory and more accuracy at longer ranges. Because a round of ammunition needed less powder, its caliber could be reduced making it lighter. That would allow troops to carry more ammunition. It would even detonate when wet. We are talkin’ really cool stuff here.

<

Please view the illustrations showing sectional views of the base of a Boxer primed case and the sectional view of a bottlenecked rifle cartridge. These illustrations are meant to show the relative scale and relationship of the components.

Illustration of a A section view of a completely assembled bottle necked cartridge case or round
A section view of a completely assembled bottle necked cartridge case or round.

In yet another ironic twist of fate, in 1887 Alfred Nobel — using profits from his discovery of dynamite — instituted “The Nobel Peace Prize.” He later developed a smokeless gunpowder called ballistite. Today, propellants based on nitrocellulose alone are known as single-base, whereas cordite-like mixtures are known as double-base.

Smokeless powder allowed the development of modern semi- and fully-automatic firearms. Single and double-base smokeless powders now make up the majority of the propellants used in firearms today. They are so common in fact that most references to “gunpowder” refer to smokeless powder, especially when referring to small arms ammunition. So “The Peace Prize” is given out by the guy responsible for killing the most people. Like I said… “Ironic!”

BTW, if you are a reloader, it must be noted that the Berdan primer is hard to remove from the cartridge case without damaging the anvil. This is why it is used by many European and Asian manufacturers (especially Eastern bloc) because they want to discourage the practice of reloading. That has not, however, altered the fact that many guerrilla fighters have reloaded Berdan cartridges using a match head and a piece of tin for the primer.

cartridge case going through the first step of the reloading process on a single stage press
A cartridge case going through the first step of the reloading process on a single-stage press.

The Boxer priming system was originally more complex to manufacture because the primer has two parts (the anvil and the priming cap). But the introduction of automated manufacturing eliminated the difficulty of making Boxer primed cartridges and they became simpler to manufacture even though the priming system is more complex. Since reloading Boxer primed cartridges is much easier, it became more popular in the United States, almost completely replacing the Berdan system.

The vast variety in types of firearms, calibers, and gauges can be confusing and bewildering to the novice. One could rightly ask, “Why so many?” The answer lies in the different uses for firearms and their development. Firearms are, after all, tools designed to accomplish a specific task. Like other tools, you would not use a hammer to turn a screw. Likewise, you do not use a pistol to shoot clay targets. Because of the plethora of cartridge sizes and shapes, only some brief generalizations can be covered here.

Caliber Confusion

First off, there seems to be a lot of confusion — especially with new shooters — as to just what the term caliber means. So, let me try to clarify that first. Caliber refers simultaneously to the bullet diameter and the size and shape of the cartridge along with a description attached to it, such as 30/06 Springfield. Although a numerical size is stated in the name, it does not always represent the correct dimension. See? I said it was confusing. An example would be the 30 in the 30/06 which would lead one to believe the diameter is .30 but they would be wrong, it is actually .308. The .38 Special is actually .357 and the .303 British, also called the 7.7X56mmR, is actually .312. Confusing huh?

20 different caliber handgun cartridges
Some of the benefits of modern technology on the cartridges available to us today. From left to right: .22 Long, .22 Long Rifle, .32 ACP, .380 ACP, .380 ACP, .30 Luger, 9mm Luger, .40 S&W, .40 S&W, .45 ACP, .45 ACP, .38 Special, .38 Special, .357 Magnum, .30 M1 Carbine, .38/40, .44 Magnum and the .454 Casull.

Nations under the Imperial system of measurement use fractions of an inch most often in 100s as seen above. Nations on the Metric system use millimeters. More confusing still, older cartridges designed in the “Black Powder Era” have several numbers attached such as,”22-15-60 Stevens” or the “45-120-31/4 Sharps. Those types of names usually start with bullet diameter, followed by the size of the powder charge followed by the length of the cartridge case, and then the name of the company or designer/inventor.

The 9.3 X 80R tells us that the bullet diameter is 9.3mm and that the case is 80mm long. The letter “R” indicates it is a rimmed case. The 30/06 Springfield gives us the bullet diameter, the year adopted for service, and the firearm it is intended for. Some even have more than one name such as the 9mm Luger, 9×19, or 9mm Parabellum. Only interest, exposure, and education can help one understand this largely unregulated and creative naming process.

I hope this abbreviated attempt provides a better understanding of the make-up, history, and nomenclature of the ammunition we take for granted.

The evolution of modern ammunition has a storied history mixed with innovation and flops. What is your favorite cartridge? Share your answer in the comment section.

The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (15)

  1. As an addendum to my earlier post, my comment regarding fat man was my attempt at humour since the author himself referred to himself as that. Just in case author sees it!!
    I really enjoy his posts

  2. As an addendum to my earlier comment, I do not wish to slight the author in any ways I to explain my “fat man” comment was referencing his excellent earlier article on concealed carry when he referred to himself as “the fat man” I thought it quite humorous! Great articles. Thank you

  3. One small error. There is only one compound in a primer. There is no mixing, the compound used “goes off” when struck a sharp blow. Lead azide was one of the first compounds used, mercuric fulminate was a later one. I don’t know what they use now.

  4. Outstanding article and a concise explanation of modern Firearm Ammunition form and function.
    This should be mandatory reading for the Dullards in the Film Industry who still seem to think that the entire Cartridge shoots out of the Gun’s Barrel.

  5. “…cartridges designed in the “Black Powder Era” have several numbers attached such as,”22-15-60 Stevens” or the “45-120-3 1/4 Sharps. Those types of names usually start with bullet diameter, followed by the size of the powder charge followed by the length of the cartridge case…”

    While it’s true with metric cartridges that the 3rd number refers to case length, it’s generally not true with most of the “Black Powder Era” cartridges, (Sharps being a notable exception!). With those old-timers the 3rd number denotes the weight of the bullet in grains, not the case length, e.g., .22 cal – 15 grs blk pwdr – 60 grs b’t. Otherwise, a really well-done and much-needed summary!

  6. I own a hi point 45 cal.love it
    Perfect for everything I need
    Wish someone would tell me where I can get 15 or 20 round mags. Would love to have someone help me
    Walter
    I have not already said this!!!

  7. I own a hi point 45 cal.love it
    Perfect for everything I need
    Wish someone would tell me where I can get 15 or 20 round mags. Would love to have someone help me
    Walter

  8. In answer to Mikes question: Belted cartridge design was introduced by the British firm of Holland & Holland for their proprietary calibers, where the chamber is shaped to seat the forward face of the belt. Because of the their proprietary shape it was not possible to provide proper headspacing for their new cartridge design. Holland’s solution was to add a belt around the cartridge body similar in function to the rim of a rimmed cartridge case head. Look for a future article by me that will cover belts and headspace in more detail.Thank you for your interest.

  9. Good article. The author compressed a vast amount of information into a pretty small space as the evolution of modern ammunition is a lengthy subject.
    I’ve always found it ironic, as pointed out, that the ‘Noble Peace Prize’ is named after the man who developed dynamite, along with various ammunition propellants that were used in weapons of war.

  10. Wonderful and informative article. Could you also explain the what belted cases means?
    Thank you and please keep further such articles coming.

  11. The Fat Man really knows his stuff! Fascinating and important information indeed. Thank you job well done… I am now edja-ma-kated!!

  12. Super interesting! I have heard several of these terms before but did not know the details or history described here. Great article – I would be very interested in reading more of this – if there is more? Hopefully the Author can expand on this history lesson in future articles.
    And who knew the Nobel Peace prize was financed by weapons development! Crazy…

Your email address will not be published. Required fields are marked *

Your discussions, feedback and comments are welcome here as long as they are relevant and insightful. Please be respectful of others. We reserve the right to edit as appropriate, delete profane, harassing, abusive and spam comments or posts, and block repeat offenders. All comments are held for moderation and will appear after approval.