Theres a long list of descriptive words, but they all mean the same thing: cartridge.
It can become confusing because some names refer to only a component of the cartridge, like bullet.
Bullets come in different shapes and weights.
A centerfire cartridge has four basic parts: the bullet, the case, the powder and the primer. Image: Hornady Manufacturing Company
Bullet weights are measured in grains.
There are a variety of different bullet types depending on the popularity of the caliber.
For instance, in 9mm alone there is a wide range of options, most commonly from 115-gr.
Bullets are the projectiles that exit the firearm and fly toward the target. They are only one of four primary parts in a centerfire cartridge. There are many different types and styles of bullets.
FMJs (full metal jacket) to 147-gr.
JHP (jacketed hollow points), and a whole lot more.
You choose a bullet key in depending on its specific purpose and your needs.
A hollow point bullet is designed to expand when striking soft tissue. This sequence shows a bullet expansion from unfired to completely expanded. Image: Hornady Manufacturing Company
Are you concealed carrying?
Is your gun in the bedside table ready to serve for home defense?
Target shooting and hunting are other applications that use specifically designed bullets.
Cartridge cases hold all of the parts together. Many cases are made of brass, while some are made of aluminum or steel. Image: Hornady Manufacturing Company
Keeping with our 9mm example, most 9mm bullets have a lead core surrounded by a thin copper jacket.
The jacket allows the bullet to be driven at higher velocities (and reduces fouling in the bore).
Lead-free bullets omit the lead and are usually made from a copper alloy.
Propellants, or powders, come in a variety of chemical formulations and shapes that allow manufacturers to create cartridges that serve different purposes. Image: Hornady Manufacturing Company
A good training bullet option are FMJ bullets.
These bullets have a rounded nose and are designed to run smoothly and reliably in most pistols.
They are also generally inexpensive.
Primers are the circular disks in the “bottom” of the cartridge case. It provides the spark that ignites the powder.
The most common 9mm FMJ bullets weights are 115, 124, and 147 grains.
A good approach is to choose a bullet based on how it cycles in your gun.
Its all about Newtons third law: To every action, there is always opposed an equal reaction… Each ammunition manufacturer puts their own spin on bullet design, but the basic design approach is very similar.
Choose a hollow point bullet for defensive use.
Again, popular 9mm hollow point bullet weights are 115, 124, and 147 grains.
The case is usually made of brass, but there is inexpensive ammunition made with steel or aluminum cases.
Some premium ammunition is nickel-plated.
The nickel plate provides a slicker surface for better cycling.
A case has a mouth, which is the open end that holds the bullet.
The head also contains the head stamp, or writing that identifies the caliber and the manufacturer.
Case sizes and shapes vary depending on caliber.
Centerfire cases fall into two categories: either bottleneck or straight wall.
A bottleneck cartridge has a distinct shoulder that necks down from the case body diameter to a smaller mouth.
An example of rifle bottleneck cartridges is the 5.56 and 6.5 Creedmoor for rifles.
Bottleneck pistol cartridges are much more rare.
Most rifle cartridges have a bottleneck case design.
Straight wall cartridges have a body and neck of the same size.
The rim on the head of the case has several configurations.
Rimmed cases have a rim that protrudes past the case body.
Calibers like .22 LR and .38 Special use a rimmed case.
Rimless cases do actually have a rim, but it is the same diameter as the case body.
It features a groove for the extractor to grab down into.
The .380 Auto, 9mm, .45 Auto and 10mm Auto are all rimless pistol calibers.
Examples of rimless rifle calibers include 5.56 and .308 Winchester.
Semi-rimmed case have a rim slightly larger than the case body.
Pistol calibers like .25 Auto and .32 ACP are semi-rimmed, as well as some rifle calibers.
These cases are mainly used in magnum rifle calibers like 7mm Remington Magnum.
Powder The Propellant
Powder is the propellant.
All modern cartridges use smokeless powder that is made up of either nitrocellulose or nitrocellulose and nitroglycerin.
A primer is a tiny metal cup that is filled with priming compound with an anvil placed over it.
In rimfire cases, the priming powder is embedded inside the case within the rim.
Conclusion
So there you have it.
There are four components to every pistol and rifle cartridge.
