Arbitrary Divisions

Mission Statement
The purpose of this chapter is to quickly point out some of the ways shooters divide up ammunition. I have used the term “arbitrary” because as one will find when dealing with weapons hard and fast rules often get broken. Also, the distinctions are fluid and flexible. Two cartridges that were paired off against each other in one comparison may be associated in another. These groupings are helpful but not ironclad.

Some Divisions

1. .22 vs. The Rest
When people talk about “22’s” they invariably mean .22 rimfire ammunition. In rimfire ammunition, instead of a primer pocket and primer in the center of the cartridge head, the rim of the shell is hollow and filled with primer compound. The hammer of the gun crushes the rim and detonates the primer compound. Rimfires only work with low pressure rounds because the hollow rim is weak compared to solid rims of centerfire rounds.

The only rimfires currently in production are the .22 caliber rimfires. The most popular is the .22 Long Rifle or .22LR. This cartridge is followed by the .22 Short and the .22 Long and the .22 Winchester Magnum Rimfire or .22 Magnum. There are also variants of the .22LR that make use of the tolerances in the firing chambers of rifles chambered for .22LR to stretch the cartridge slightly. The .22LR and near-.22LRs, along with the .22 Short, Long and Magnums ( and a couple of really odd .22’s) make up the family of rimfire 22’s.

There are a lot of interesting things about .22 rimfires, but one of the most salient features about them is that they are the only commercially produced cartridges utilizing an outside lubricated bullet. Previously in our dealings with bullets, we described them as inserted into the case mouth, and then crimped into place. The accompanying diagram shows a bullet slipped into the case mouth, necessitating that their greatest diameter be smaller than the inside diameter of the cartridge case. Rimfire .22s use a bullet construction with a heel. The heel is slipped into the case mouth and the larger part of the bullet rests on the case mouth. Since the heel is of a smaller diameter than the main part of the bullet, the lubrication cannelures are etched into the exposed part of the bullet, specifically its bearing surface, or the part of the bullet that actually makes contact with the inside of the barrell. This is part of the reason why .22 rounds feel slippery. These rounds often come in cardboard boxes containing fifty rounds. If one were to remove the cartridges, one would notice the grease stains at the bottom of the box. In fact, the Russian plinking .22 caliber ammunition now on the American market is lubricated after cartridge construction, so the whole round is coated in grease.

There is also a variety of 22 caliber centerfire cartridges. These cartridges, with bigger, bottlenecked case bodies, provide high speed and accuracy. The most famous .22 caliber centerfire cartridge may be the .223 Remington In its military version it is called the 5.56MM Nato. This is the cartridge used by the US armed forces in the M16 assault rifle.

There is sometimes call to separate .22 caliber centerfire and .22 rimfires from the balance of modern cartridges s ince they both are used for hunting smaller game. In fact, the Savage-manufactured military survival rifle of WWII switched from .22LR to a jacketed 22 centerfire. Even today, military survival rifles offered to the public are chambered in .22LR while the military version remains 22 centerfire.

2. Rimfire vs. Centerfire
The 22 rimfires are extremely popular but are simultaneously limited in scope of usage. Consequently, they are usually categorized as a class of ammunition unto themselves, and the balance of the modern cartridge world is grouped as the remaining centerfire cartridges. This is the far more popular division of cartridges.

3. Caliber Classes
Many times ammunition is grouped by a class of caliber. For instance, we’ve seen the grouping of .22 caliber centerfire rounds. There are also groupings for 7MM cartridges, 30 caliber cartridges, and less-than-.22 caliber centerfire cartridges, to name a few. The bullet diameters of these rounds are by no means the same, nor are the performance characteristics identical, but cartridges can be associated with each other in ball parks of similarity. Pistols ammunition is grouped sometimes the same way, where .30 caliber rounds are associated, .32 caliber rounds, .35 caliber rounds, .40 caliber rounds, et cetera.

4. Rifle vs. Pistol
There is a distinction in modern ammunition between rifle and pistol ammunition. Pistol ammunition is meant to be accurate and carry sufficient energy down range for maybe a hundred feet. Rifle ammunition often is expected to perform a thousands of feet. Modern pistol ammunition usually operates at far less pressure than average rifle rounds, and usually has straight wall cases. Often these cases are rimmed. Rifle ammunition in many cases makes use of the bottleneck design for holding significant amounts of powder in a short case length.

Don’t think though that this distinction isn’t blurred. There are plenty of pistols, like the single shot Contender, that fires a host of rifle ammunition. Plus, there are many short rifles that use pistol ammunition. Rifle and pistol combinations where the two pieces fire the same cartridge have been common in American gun history; such rifles are often marketed as ‘carbines.’ Sometimes the cartridge in question is loaded for higher pressures and thus more velocity to better utilize the benefits of a rifle, however the cartridge will chamber and fire in a pistol chambered for that cartridge. Sub machine guns, a whole type of military arm, almost by definition fires pistol cartridges despite its rifle-like characteristics.

5. Target vs. Combat vs.Hunting
There is always a tremendous debate raging amongst gun writers and military and police personnel regarding the “best” combat cartridge. If one follows these articles, one can see that only a handful of cartridges are even considered. A useful distinction amongst cartridges are those that are appropriate for combat use, those for hunting, and those for target. Cartridges for hunting are chosen on what game is considered. Cartridges used for target or competition are chosen based on the nature of the competition.

6. Autoloader vs. Revolver
A very useful distinction between cartridges is whether they are designed to function in an autoloader or a revolver. Revolver ammunition has historically been designed with a rimmed head so that it will seat in a revolver cylinder’s chamber. Autoloading ammunition has been historically designed with a rimless head to ease the mechanical loading and unloading the the brass. Don’t get too hung up here either on these distinctions. There are plenty of autoloading pistols that fire rimmed ammunition and revolvers that fire rimless ammunition.

Some Thoughts