When it comes to ammo, it can get confusing trying to get the proper nomenclature down. Over the years the meaning of words has been diluted down as they tend to be used interchangeably, even though they may be wrong. So to help you understand how to talk ammo I came up with a list of definitions that will have you out-Grammar-Nazi’ing my editor. (Editor’s note: I saw that.)
Ammo/Ammunition: comes from the word “munitions,” which was originally used to describe military weapons and the supplies used to keep them functioning. Ammunition or Ammo for short is just the total quantity of cartridges or shells in a location.
Round: is a single unit of ammunition.
Both words are used to describe the amount of ammo. But think of ammo as the whole generic amount available.
Cartridge: describes all of the components of ammunition together as an assembly. It typically consists of four components: the bullet, casing, gunpowder, and the primer. “Cartridge” is only used when talking about rifle or pistol ammunition.
Shell: Is also another word for the casing used to house the ammunition components. Shells are used in rifles, pistols, and shotguns. Where it gets confusing is sometimes “shells” is used as slang for rounds. So in movies actors will ask for more shells, because their firearm is empty. The shell is specifically the casing, so if you hand them expended ammo casings you are giving them what they asked for.
Brass: This is another slang term for the empty casing or shells. Now I am sure you just tried to jump ahead and say, but it’s used for casings that are brass right? Nope—ammo casings come in all forms of construction, from brass, aluminum, and steel, to polymer and plastic. In today’s day and age, brass has ended up becoming another generic term to describe the empty shells or casings. It does not matter what kind of ammo you shot; it’s all “brass.”
Shotshell: Ahh, finally we have a term that is NOT interchangeable. A shotshell is used to describe shotgun ammunition. Basic shotshells are made up of five components: The shell, primer, gunpowder, wad, and projectile. Shotgun shell bodies can be made from paper or plastic and have a metallic base that houses the primer.
The wad is the material that seals and separates the gunpowder from the projectile. For projectiles shotguns use “shot” of different sizes … think of BBs, or small ball bearings. Shotguns can also use slugs in combination or instead of shot. Ammo manufacturers make shotshells specific for pistols and rifles as well. Example: .22LR “rat shot” is a shotgun shell scaled down to fit in a .22LR. These are great to take care of small rodents and the like.
Anatomy of a pew
Bullet: Is the actual projectile that flies though the air at high speed and hits the target. Shot and slugs are bullets as well, since they they are the part of the ammo that is fired towards the target.
Casing: is the container that holds everything used for ammunition. It holds the primer, powder, wad (shotshells), and bullet or shot.
Primer: is the part of the cartridge that holds a small amount of starter chemical. When the firing pin hits the primer, it causes a small explosion, which ignites the gunpowder.
Gunpowder: is the main explosive used to propel the bullet, shot, or slug.
Head Stamp: these are the markings that are located at the base of the shell. This is where you can find information like the caliber of the cartridge, manufacturer name, and/or the date of manufacture.
Size means everything
Caliber: the caliber of a firearm is the internal diameter of the bore. Note that the caliber can be expressed in both metric and inches. So 9mm ammo will have a diameter of 9mm. Whereas, a .50 caliber measures half an inch. Interesting to note .223 and 5.56mm both have the exact same diameter and in most modern AR15s are interchangeable.
Gauge: is the measurement of the diameter of the bore, but in weight. It’s a little math and can seem confusing at first, but follow along with me. You take the inner diameter of the shotgun’s bore. Then you make a solid lead sphere of that same diameter. Then you multiply how many of those lead balls it takes to make 1 pound.
So, for a 12 gauge you would need 12 lead bore diameter balls to make 1 pound of weight. The larger the gauge, the more of those balls you need to equal one pound since the balls are smaller and smaller diameter. Take the 16 gauge; since the diameter is smaller than a 12 gauge, you would need 16 balls to equal the weight of one pound. 20gs is even smaller and you would need 20 lead balls the diameter of the bore to equal the weight of one pound.
You are probably asking why the hell would you measure something like that? It goes way back to how they measured cannonballs. Cannonballs were measured by weight and it transferred over. You are not going to be quizzed on this, so just remember: the smaller the gauge, the bigger the diameter. 10ga packs a bigger punch than 20ga. Wait what about .410 ammo? Well that’s actually a caliber, not a gauge. Even though it is definitely a shotgun cartridge, it is measured by the diameter of the bore—410/inch—and not the weight.
Types of Ammo
Centerfire: is any ammo in which the primer is located in the center of the back end of the case. Most rifles, pistols, and shotguns use centerfire ammunition.
Rimfire: Is a cartridge where the primer is located on the outer edge of the case instead of the center. The most popular example is the .22LR ,where the firing pin hits the edge of the case to ignite the round.
Rimless: When you look at the side profile of rimless ammunition, the rim (back end) is no larger than the diameter of the case. Rimless ammo is mostly used in semi-auto firearms. Since the rim does not extend past the diameter of the case, rimless rounds tend to cycle better than rimmed counterparts.
Rimmed: this type of ammunition has an extended rim that is proud of the main shell body. This is most common with revolver and shotgun ammo. This type of ammo is available as centerfire or rimfire. Whereas most revolver, lever action, or shotgun ammo is centerfire, you’ll see products like .22LR and .17 HMR that have rimmed primers.
Lead Ammo: Lead ammo is cast from lead, and in examples like .38 Spl., the lead is exposed and comprises the whole bullet.
Jacketed Ammo: Is going to have a lead center, but with an additional metal cover that has been applied over part of the lead core.
Full metal jacket: SIR, YES SIR! Gomer Pyle says that these can still have a lead core, but the metal cover fully encases the lead core.
Round-Nose Ammo: has a bullet that has a round nose on the tip. The benefit is that this type of ammo is the most reliable as far are feeding into firearms. The downside is that round-nose ammo is usually not best suited for personal defense or duty use.
Hollowpoints: the best way to describe this ammo is to think of a volcano—a cone shape with a hollow center. The theory behind this design is that when the bullet hits a meaty target, the cone gets filled up and hydrostatic pressure expands the hollow center. This instant expansion increases lethality as it transfers energy into the target.
+P and +P+ Ammo: All ammunition has set normal working pressures that engineers design into the caliber. Because these are known pressures, firearms manufacturers can design firearms that can safely handle these normal working pressures. More velocity means a harder hitting round. This increased pressure ammo is known as +P & +P+ and is only meant to be used in modern firearms. A warning: Even some modern firearms will tell you that you will void the warranty using increased pressure ammo.
As of right now, all televised police dramas will annoy you. Detective: “Sergeant, make sure to tag and bag all of these shell casings.” Please don’t look at your loved one and sarcastically say: “What idiots! A shell and a casing are the same thing, I bet they say VIN Number (vehicle Identification Number Number) next!” Nobody likes a grammar nazi (Editor’s Note: I saw that, too.). But hey! At least you’re now an interpreter who can speak multiple languages.
—James the “XDMAN” Nicholas Mr. UnPewFessional Himself
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