Ammunition is a very confusing topic for most shooters.  In order to understand how the terminology and designations were arrived at, you have to know something about the history of the mid-19th through mid-20th centuries, both in the U.S. and in Europe.  Let's review the state-of-the-art for pistols, rifles, and shotguns about 1850: (1) nearly all are muzzle loaders; (2) nearly all are smooth bores with rifled barrel systems taking over; (3) most are single shots (or two for shotguns) and there is a choice in pistols due to the new Colt 5-shot Patterson .36 caliber and Colt-Waker .44 caliber revolvers.  Ammunition is composed of: (1) a black powder charge, (2) a single projectile (pistols, long guns) or shot (shotguns), and ignition source (flint for flintlocks or caps for percussion locks).

 

Around 1850 the percussion cap was developed into the CB cap.  The CB cap was a .22 led ball in a copper case with the priming compound formed inside the rolled rim (hence, rimfire case).  At the same time (1852) the Volcanic system was brought out that consisted of a lever action pistol with self-contained ammunition.  The projectile of the Volcanic was hollow to contain both black powder and primer.  The company of Smith and Wesson was formed to produce the Volcanic pistol.  Unfortunately the Volcanic was not successful (primarily due to the unreliability of its ammunition, lack of power, and the expense of the gun).  However, the CB cap was evolved into the .22 SHORT cartridge by the addition of 4 grains of black powder.  (The .22 Short is the oldest of the self-contained cartridges still in production 150 years later.)

 

S&W brought out the first successful cartridge revolver, the Model 1, in 1857.  The Model 1 was a .22 Short, 5-shot, top break, pocket revolver for close quarters self-defense and pioneered the use of the bored-through cylinder for self-contained cartridge ammunition: (1) bullet, (2) powder, (3) case, and (4) primer.  The next step was to double the size of the .22 Short to .44 caliber rimfire.

 

The old Volcanic system was purchased by Oliver Winchester.  Winchester hired B. Tyler Henry to redesign it and he created the Henry lever action repeating rifle in .44 rimfire by 1860.  The Henry was produced in both rifle and carbine lengths and could carry up to 17 rounds of .44 ammunition in some models.  It was very expensive to make, the ammunition was hard to get, and both gun and ammo were expensive for buyers.  To say the design was revolutionary would be an understatement.  In the U.S. Army, state-of-the-art meant (1861) the Springfield .58 caliber rifled musket.  The Springfield was a .58 caliber muzzle loader that used percussion caps, had a rifled barrel, and was designed for either patched round ball bullets or the new conical Minie ball bullet.  The Army's "cartridges" for the Springfield were actually speed loaders -- a paper case that held a pre-measured powder charge and either a round ball or Minie ball -- percussion caps we carried in a separate cap box along with the soldier's separate cartridge box of 60 rounds.

 

The American Civil war of 1861 to 1865 accelerated cartridge development in the United States to unheard of levels.  Some far-sighted American officers even proposed issuing repeating arms to their troops.  President Lincoln got the hide-bound U.S. Army Ordnance officer Ripley to procure 7-shot .56 caliber rimfire Spencer rifles and carbines for Union troops.  Some Union troops purchased Henry .44 rimfire rifles for themselves.  But, it was the harsh realities of war that forced the Army to adopt more "modern" arms.  No, not the new-fangled repeating arms, but a modern single-shot metal cartridge, centerfire rifle and carbine.

 

The Army wanted a rifle and carbine that (1) had long range and (2) did not waste expensive (!) ammunition.  The Army saw that the Henry and Spencer rifles and carbines could produce great firepower, but both lacked range due to the size of cartridge case used.  The officers of the time were also concerned about supplying the troops with enough ammunition -- they viewed the repeaters as prodigious ammunition hogs -- and felt that a single-shot breech loader was the solution (and it was cheaper to convert the tons of war surplus rifled muskets on hand).  By the end of the war (1865), the Army was on its way to the "solution" -- a modification of the 1861 .58 caliber Springfield rifled musket -- into the breech loading 1873 "trapdoor" rifle and carbine. 

 

The Army realized that it needed a system to classify the newly created ammunition and so it decided to do it by: (1) caliber, (2) powder charge, and (3) bullet weight.  The new type classified ammunition was called the .45-70-405 for rifles and .45-55-405 for carbines.  At the same time, the cartridge case itself was undergoing rapid development by a British Army officer, Col. Boxer, and an American, Col. Berdan.  Both came up with the idea of making cases formed or coiled copper or brass and both designs relocated the percussion primer to the centerline axis of the new case.  The centerfire case was born and rapidly replaced all other designs.  [Today, American ammunition uses a blend of the Berdan cartridge case (single flash hole) and the Boxer primer (with its integral anvil and primer in a cup) ; Europeans use a Berdan case with double flash holes and a cast-in anvil to compliment its larger primer and primer compound.]

 

The problem with all of these cartridges was the propellant: black powder.  Black powder is a mix of charcoal, sulfur, and salt peter.  However, it leaves a very corrosive and filthy residue after combustion that eventually fouls the arms using it so as to require cleaning before continued use.  A new development called "guncotton" was developed in 1846.  However, guncotton was not suitable as a propellant in firearms and was used as an explosive.  The solution was found in 1884 by a Frenchman, Paul Vieille, who brought Poudre B to market.  This was the first smokeless powder. 

 

Smokeless powder was the answer to the ages old problems with black powder as a propellant: (1) smokelss powder did not produce the clouds of white and gray smoke that black powder did, (2) it burned exceptionally clean and did not foul the using firearms, and (3) it was extremely powerful and produced exceptional muzzle velocities for the projectiles fired.  [These higher muzzle velocitys forced the development of metal-jacketed projectiles, because the lead bullets of the time could not take the increased pressures or velocities the smokeless powders produced.]  The first rifle to fire this new powder was the Model 1888 French Lebel rifle.  About the same time, the British developed a different variation of smokeless powder that they called Ballistite (also known as "Cordite").  Both of these powder types revolutionized small arms ammunition by making the ammunition lighter, the bullets smaller, and the engagement ranges longer.

 

In 1892, the U.S. Army decided to replace its various models of single-shot Springfields with a modern breech loading repeater.  It settled on the Danish-Norwegian Krag-Jorgensen bolt action design.  The Krag carried five rounds in a side mounted box magazine on the side of the rifle.  The Krag was the first American infantry rifle and cavalry carbine to shoot the new smokeless ammuntion and this caused a problem in nomenclature.  Originally, the Krag cartridge was called the .30-40-220 after the old way of classifying black powder ammunition.  However, this was later changed to .30 Government (military) or .30-40 Krag (commercial). 

 

The new Krag got its baptism of fire during the Spanish-American War of 1898 and was found wanting.  The Spanish 1891 7mm Mauser rifles were clearly superior to the Krag.  And so, the Americans went back to the drawing board, eventually settling on modified Mauser design called the Magazine Rifle, Caliber .30-03.  This was standardized as the U.S. Rifle, Cal. .30, M1903.  Production commenced at Springfield Armory in 1903 and at Rock Island Arsenal in 1906.  The Krag rifle was phased-out of service in 10 years, but continued to soldier on in various capacities until the end of World War 2.

 

When a new .30 government cartridge was developed at Springfield Armory in 1903 (and improved in 1906), this was called simply the .30-03 and then .30-06 (or caliber .30) by the military and .30-06 Springfield in commercial loadings.  As loaded in 1903, the round used a 220-grain round nosed bullet.  As revised in 1906, the bullet was changed to a 173-grain, streamlined bullet with a tapered tail. 

 

As confusing as the military changes in development during these years is, an even more confusing situation existed on the other side of the house -- the commercial world -- where it was a free for all.  Commercial manufacturers named ammuniton any way they wanted and with no thought as to the confusion they were generating.  Designations often reflected the manufacturer's name and sometimes there was a mix of both the older and newer powder technologies thrown in.  One manufacturer marked a brand of ammuntion called "Less-Smok" -- a combination of both smokeless and black powders.

 

The Europeans ran into the same kind of chaos, except theirs was even worse.  Eventually, they standardized on the system they use now: (1) bullet diameter in millimeters, (2) case length in millimeters, and (3) cartrdige characteristics indicated by a letter or letter combination -- rimless (none), rimmed (R), semi-rimmed (SR), rebated rimless (RB), belted (B).

 

So, that's the confusing story about how cartridge type ammunition has evolved.  It has been haphazard and without any coherent plan.  While designations in the U.S. military have adopted the European pattern (as the result of NATO's organization in 1949), the Commercial world is just as fluid and confusing as it ever was.

 

For the shooter, the most important thing you need to know is what caliber your firearm shoots.  Then learn what its eqivalent names are -- such as 7.62x63 or caliber .30 M2 or .30-06 Springfield.  For a lot of shooters, that's all they care about. 

 

However, for other shootes, the mystery of why a particular round of ammunition is named as it is can be an interesting historical experience.  Remember that all of this flurry of ammunition and firearms development is very, very recent (less than a century).  What is even more astounding -- more was accomplished in modernizing firearms in that 100 years than had happend to them in the previous 1,000.