Parts of a cartridge or round
By MARJ LAW
“Can I come over?” asks Ellen. “I want to show you something.”
“Sure, Ellen,” I reply. “Is something wrong?”
“Yes. The gun shop I went to sold me a bunch of junk.”
“Come on over and let me see.” I wonder why Ellen would say that.
Ellen comes over and dumps a box of bullets on the table.
“See?” she asks. “See? I ask for a box of bullets and this is what I get. What good are these things going to do for my new 9mm Kimber Mako? I bought these because they were cheaper than other bullets for a 9mm handgun, but these won’t do me any good. Why would the guy sell these to me?”
I look at the box. Sure enough, it says bullets.
“Ellen, why did you ask for bullets?”
“Because that’s what the Mako takes! 9mm bullets! Can you believe that guy selling me all these tiny copper pieces?”
“Well, Ellen. You asked for bullets, and bullets is what we have here. I think you meant that you needed cartridges or rounds.”
“No, Marj. I wanted bullets to shoot out of my Mako. This box says ‘bullets.’ What’s wrong?”
“What you really want is cartridges or rounds,” I say again patiently. “Bullets are just a part of a round. They are the projectile that comes out when you shoot a firearm, but a round is more than a bullet. A round consists of the casing, primer, powder and last: the bullet. You need all these components.”
“So, how do I get the entire round?”
“Go back to the store and ask for 9mm rounds or ammo for your Mako.”
“Can you tell me the difference?”
“The ammo you’re looking for has 4 parts to it. It has a casing, which is often the brass, steel, or copper part. This holds the round together.
The primer is an explosive chemical compound. It ignites when your Mako’s firing pin whacks it.”
“Next,” I continued, “you have powder or ‘charge’ inside the casing. This is the propellant that pushes the bullet out of your barrel.”
“Last, you have the bullet, which is the projectile. That’s what is on the table now.”
“So, I only bought part of the round. I need to buy the whole thing put together to be able to shoot.”
“That’s right. You asked for bullets, and the shop seller sold you exactly what you asked for. He wasn’t trying to rip you off!”
“So, why would anyone want to purchase just part of a round, and not the whole thing?” Ellen wondered.
“Some people want to load their own rounds.”
“Why would they want to do that?”
“Well, some people save their spent brass casings and buy the primers, powder and bullets. They feel they have control over the exact amount of powder that is in each round. Some like to make their rounds ‘hotter’ than store-bought rounds. In my opinion, that is not a safe thing to do as you sure don’t want to exceed your gun’s tolerance.”
“Seems like a lot of work when you can just buy them. And I did see some boxes that said 9mm on them, but they said different things like 115, 124 and 147 grains. I didn’t understand the difference.”
“The grains is weight of the bullet or projectile.”
“How do I know which grained rounds I need for my Mako?”
“All will work in your Mako, but you may find that one works better than another. The only way to find this out is to shoot all 3 and see what works best in your handgun.”
“Okay.” Ellen seems convinced.
“But the round for my .22 Mark IV Ruger looks a lot different than the rounds for my Mako. Why is that?”
“Let’s look at it. See the .22 is a lot smaller and the back of the casing is flat. The .22 round has its primer on its rim. The firing pin hits the primer on its rim. We call this a ‘rimfire’ round.
“I’ve heard the term rimfire. Someone told me you can’t dryfire a rimfire round, but you can dryfire a 9mm round. Why is that?”
“If you dryfire a .22, the firing pin won’t be able to hit the rim of the ammo. Instead, it will hit the frame of the gun. This could damage or break off the firing pin.”
“Yikes!” Ellen looks worried. “I bet that’s an expensive mistake!”
“Yes. We never dryfire our .22 semi-automatic handguns. Your 9mm Mako is another matter altogether.”
“Why?” asks Ellen.
I hold up a 9mm round.
“Now, see the small circle in the back of the 9mm round?” Ellen nods.
“That’s where the primer is located on the 9mm round. Instead of hitting the casing on its rim, your striker is now hitting the center of the round. We call this one a ‘centerfire’ round. You can dryfire these handguns because if there is no round in the gun, the striker won’t hit any part of the frame and therefore won’t be damaged.”
“What about other handguns? How do you know if they are rimfire or centerfire?”
“Just look at the back of the casing. If you see the small circle, it’s a centerfire round. Most cartridges except for .22s and a few others are centerfire rounds.”
“So, let me think about this,” Ellen ponders. “When I shoot my .22, the firing pin whacks the rim, which sets of the spark which ignites the powder. This explosion sets the bullet off to my target.”
“In my 9mm Mako,” she continues, “the striker hits the center of the casing. This is where the primer is located. When whacked by the firing pin, the primer ignites the powder which sets of the explosion to push the bullet out of the barrel. It’s like a chain reaction.”
“It’s like the song ‘Dem Bones.’
The striker hits on the pri-mer,
The primer sets off the pow-der.
The powder forces out the bull-et,
The bullet makes a hole in the tar-get.
Now hear the song of the range!”
Marj Law is the former director of Keep Wakulla County Beautiful who has become an avid shooter in retirement.