Are Rifle Calibers Getting Smaller?

In the last 50 years or so, there have been several arguments about the 5.56x45 mm. cartridge and its small bullet. Some argue that the larger bore 7.62x51 mm. cartridge is harder hitting and therefore better. Others argue that the 5.56x45 mm. cartridge is lighter, but hits adequately, therefore a person can carry more of them. This caliber debate has been going on for a while. Bear in mind that in the early 1950s, when the 7.62x51 mm. cartridge was first introduced, several people from that era thought that *it* was a smaller cartridge! This is because it replaced the larger .30-06 cartridge which was in service since about 1906. As we will soon see, the decrease in size of cartridge calibers has actually been going on for a lot longer.

In the early part of the 19th century, soldiers mounted on horses (cavalry) were still an important part of many armies. We hear accounts of several famous cavalry battles, such as the Charge of the Light Brigade (and the lesser known Charge of the Heavy Brigade at the same battle),  Pickett's charge, Battle of Little Bighorn etc. It was the opinion of military experts of that period, that the bore of an infantry musket must be large and the bullet heavy enough, to stop a charging cavalry soldier. It was believed at that time that a smaller bullet, even with greater velocity and equal momentum  compared to a larger bullet, would only wound the foe, but not instantly disable him. However, it was later found by experiment, that the increase in velocity of a bullet makes up for what it loses in mass, and a lighter bullet has greater range and a soldier can carry more of them, which makes the infantry man much more effective in the field. Therefore, since about 1850, as firearm technology gradually started moving towards rifles, the size of bullets have been decreasing with every advance in infantry weapon technology. The following table is largely transcribed from The Gun and its Development by W.W. Greener and lists the diameters of bullets from various military forces in Europe and America from 1850.

Year	Country	Firearm	Caliber
1850	England	Brown Bess (11 bore)	.750 inch (19.2 mm.)
1850	England	Brown Bess (14 bore)	.693 inch (17.85 mm.)
1852	England	Enfield	.577 inch (14.8 mm.)
1854	Austria	28-bore rifle	.550 inch (13.8 mm.)
1860	Sweden	40-bore rifle	.488 inch (12.6 mm.)
1866	France	59-bore rifle	.433 inch (11.0 mm.)
1867	Austria	62-bore rifle	.420 inch (10.7 mm.)
1869	Switzerland	75-bore rifle	.400 inch (10.4 mm.)
1871	Germany, Spain and Holland	58-bore rifle	.433 inch (11.0 mm.)
1871	England	51-bore rifle	.450 inch (11.43 mm.)
1874	France	58-bore rifle	.433 inch (11.0 mm.)
1878	Sweden	76-bore rifle	.396 inch (10.15 mm.)
1880	Serbia	76-bore rifle	.396 inch (10.15 mm.)
1886	France and Portugal	150-bore rifle	.315 inch (8.0 mm.)
1887	Turkey		.350 inch (9.5 mm.)
1887	England	Enfield Martini	.400 inch (10.25 mm.)
1888	Germany	156-bore rifle	.311 inch (7.9 mm.)
1888	Germany	150-bore rifle	.315 inch (8.0 mm.)
1889	England	172-bore rifle	.303 inch (7.7 mm.)
1889	Belgium	173-bore rifle	.303 inch (7.65 mm.)
1889	Denmark	150-bore rifle	.315 inch (8.0 mm.)
1891	Switzerland		.295 inch (7.5 mm.)
1891	Italy		.256 inch (6.5 mm.)
1891	Russia		.300 inch (7.62 mm.)
1892	Spain		.276 inch (7.0 mm.)
1892	Holland and Romania		.256 inch (6.5 mm.)
1893	USA		.300 inch (7.62 mm.)
1895	USA (US Navy only)		.236 inch (5.87 mm.)

As can be seen in the table, the diameter and size of the bullets has been decreasing for quite a while. As propellants improved and black-powder began to be replaced by more powerful smokeless powders, the sizes and weights of the bullets began to decrease as well.

How did they name cartridges - II

When we left off in our last post, we saw that cartridges like .45-70 and .50-90 were named based on their caliber and the amount of black powder in it (e.g. .45-70 has a bullet of .45 inches in diameter and 70 grains of black powder). We also saw that if two different bullet weights were available for the same cartridge, then a 3 number scheme was used (e.g. .45-70-405 and .45-70-500, where the 405 or 500 indicates the weight of the bullet in grains). We will continue our discussion in this post.

With the invention of newer smokeless powders, cartridges still retained the same two digit naming scheme as before: e.g. the famous .30-30 Winchester rifle, .32-20 Winchester or the .30-40 Krag, which replaced the .45-70 in US military service. As before, the first number indicates the caliber (e.g. 0.30 inches diameter) and the second number indicates the amount of smokeless powder in grains.

After some years, people began to drop the amount of grains and use the year that the cartridge was introduced instead. For instance, the Springfield .30-06 cartridge. This cartridge's diameter is 0.30 inches and it was introduced in 1906 (from which we get 06) and therefore it was named as .30-06. The .30-06 actually replaced the .30-03, which was, predictably, adopted in 1903.

Some years after that, people began to drop the second number altogether and simply name the cartridge after the caliber and the company that introduced it  (e.g.) .44 Colt introduced by Colt firearms, .32 S&W invented by Smith and Wesson etc. Sometimes they were named after a specific product (e.g.) .45 ACP where ACP stands for Automatic Colt Pistol. Sometimes they were named after specific attributes (e.g.) .38 Special, .44 Magnum, .577 Express etc., where the words Special, Magnum or Express indicate that these cartridges have extra power.

By the 1950s, people also started to name the first number by the groove diameter of the rifle, rather than the bore diameter of the bullet (at least in America). For instance, .308 Winchester, where the bore diameter is 0.300 inches, but the groove diameter is 0.308 inches.

Over in Europe (except for the UK), people generally use the metric system and name cartridges with two sets of numbers separated by an "x". e.g. 7.62x51, 5.56x45 etc. The first number is the bore diameter of the bullet in millimeters (e.g. 7.62 mm., 5.56 mm. etc.) and the second number is the length of the case in millimeters (e.g. 51 mm., 45 mm. etc.). Note that the first number is the bore diameter, not the groove diameter. Therefore, what we call the .308 Winchester in America actually has a bore diameter of 0.300 inches and a groove diameter of .308 inches and the Europeans take the 0.300 inch measurement and convert that into millimeters (7.62 mm.) and use that in their cartridge nomenclature. This system is generally used in the rest of the world as well (Asia, Africa, South America, Oceania etc.)

The British tend to name their cartridges in American fashion, e.g. .244 H&H Magnum (where H&H stands for Holland and Holland, a famous British firearms firm), .455 Webley (invented by Webley, another British firearms manufacturer) .700 Nitro Express etc. The numbers indicate the diameter of the bullet rather than the groove diameter though.

These are generally the naming schemes in vogue these days, but there are exceptions to the rule. American manufacturers in particular, tend to add names that sound good to consumer ears: e.g. .22 Hornet, .221 Fireball, .224 Rocket etc. Also, there are cartridges such as the .280 Remington (which actually has a bore diameter of 0.277 inches and groove diameter of 0.284 inches) and the .260 Remington (which actually has a bore diameter of 0.256 inches and groove diameter of 0.264 inches). Remington's marketing people decided that customers like numbers that end in zero better, so they named then .280 and .260 instead.

As you can see, these are several ways how cartridges have been named throughout history.

How did they name cartridges - I

In the world of firearms history, we often see famous cartridge names like .30-30 Winchester, .45 ACP, .30-06 Springfield etc. So how exactly do cartridges get named and is there some meaning behind their naming convention. We will study those in this post.

Bear in mind that cartridges are not always referred by the same name throughout history. For example, when Smith & Wesson produced their first revolver model, they made it fire a .22 cartridge, which was then referred to as a ".22" or a ".22 caliber" in 1857, since there were no other cartridges with the same caliber bullet. This cartridge contained 4 grains of black powder in it and a bullet weighing 29 grains (or 2 grams in the metric system) and measuring .222 inches in diameter. In 1871, Smith & Wesson produced another cartridge in .22 caliber diameter. This cartridge used the same 29 grain bullet as its predecessor, but the case was a bit longer than the older one and contained more black powder (5 grains), in order to produce extra power. Therefore, they began to refer to the old .22 cartridge as ".22 Short" and the new one as ".22 Long". Both these cartridges were used for revolvers. Soon afterwards, Remington, Stevens, Winchester etc. started producing the ".22 Extra Long" for rifles and revolvers. This cartridge used a 40 grain (3 gm.) bullet and a longer case that contained 6 grains of black powder in it. Then, the Stevens Arms and Tool Company combined the case of the .22 Long with the 40 grain bullet of the .22 Extra Long to produce the ".22 Long Rifle" (a.k.a. ".22 LR" cartridge).

Public domain image of different .22 caliber cartridges.

The .22 LR became very successful and still remains the most popular cartridge in the present day. Therefore when someone talks about ".22 caliber" in today's world, they are almost certainly referring to the .22 LR cartridge. However, back between 1857 and 1871, when someone said ".22 caliber" they would have been referring to what we now call ".22 short". So you can see how common cartridge designations have changed over the years.

For some early cartridges, they were named with two sets of numbers. For instance, right after the US Civil War, the US government issued the ".50-70 Government" cartridge for use with the Springfield Model 1866 rifle. This was later replaced by the ".45-70 Government" cartridge in 1873. So what do the numbers .50-70 and .45-70 mean? For a ".50-70", it means that the cartridge has a .50 caliber bullet and 70 grains of black powder. Similarly, a ".45-70" has a .45 caliber bullet and 70 grains of black powder. This naming scheme was also used for other cartridges such as the ".50-90 Sharps", ".50-100 Sharps", ".50-110 Winchester" etc.

In some situations, these cartridges were also referred to with three sets of numbers, such as ".50-70-450" and ".45-70-405" where the third number indicated the weight of the bullet in grains. This was done as cartridges of the same size, but with different bullet weights, became common. For instance,  the .45-70 cartridge case was used for two different bullet weights and to tell them apart, the two cartridges were called .45-70-405 and .45-70-500, when the 500-grain-bullet variant was invented in 1884.

In the next section, we will look more into the conventions used to name cartridges.