Ammo Basics: Centerfire and Rimfire

Although there are hundreds of different types of ammunition cartridges available, all ammunition can be divided into one of two categories. This blog entry will briefly discuss the differences in centerfire and rimfire ammunition cartridges.

Although there are many different kinds and calibers available, they can all be broken down into one of two main categories. Centerfire or Rimfire. There is a massive difference between the two. The first kind of ammunition I am going to talk about is the rimfire cartridge. The sample rimfire cartridge pictured below is a .22 Remington.


The rimfire is designed to have the all priming compound inside the bottom curved base of the cartridge. The firing pin of the weapon that uses this ammunition has to strike the entire bottom of the cartridge to discharge the bullet. Once the base is struck with sufficient force, all the priming at the base of the cartridge will detonate, causing the main powder inside the cartridge to ignite, and then the cartridge will discharge the bullet. All this happens in a few nanoseconds.


The second kind of ammunition cartridge is the centerfire cartridge. Centerfire cartridges are different from rimfire cartridges because of where the priming compound is located. Looking at the photo below, you can see there is an inner circle on the base of these cartridges. This inner circle contains the primer for the centerfire cartridge.


The firearm that uses the centerfire kind of cartridge only needs to strike the center of the base, and not impact the entire bottom of the cartridge. Usually, this is accomplished with a small pin-like protrusion at the end of the hammer of the firearm. Once the center is struck with sufficient force by a pin-like hammer, the primer will detonate, causing the main powder inside the cartridge to ignite, thereby discharging the bullet.


In the following photo you can see a shotgun shell has the same centerfire design as the previous handgun cartridges had. As a matter of fact, it functions on the exact same concept as the previous cartridges.


So why the design difference? Centerfire cartridges, by the way of their design, are much stronger, and can accommodate more internal pressure all around. More powerful internal resistance mean higher possible pressure and velocities can be put on these kinds of cartridges. As a result, bigger bullets can be discharged with a centerfire design than what is possible with a rimfire design. Virtually all modern firearms use centerfire cartridges. Only the .22 caliber ammunition series retains the rimfire design.


Another big difference in the design is their re-usability. When rimfire cartridges are discharged, the hammer of the firearm usually damages the base of the cartridge, and the primer is completely obliterated. This makes most rimfire cartridges useless after their initial discharge. However centerfire cartridges can be re-used by simply replacing the dented center primer, reloading the cartridge with gunpowder, and capping the top with a bullet. There are specific machines that are sold just for this purpose.


Re-loading centerfire ammunition is economical, as you can purchase gunpowder and bullets separately. Re-loading centerfire ammunition also allows for custom-tuned and designed ammunition as the individual sees fit. Have you ever noticed there are always nicely collected buckets of empty cartridges at the target range?


Its because someone who works there is keeping all of them to reload later! Reloaded centerfire ammunition used to be a better deal than buying from the stores, but with certain department stores purchasing ammunition by the warehouse full and offering them at steep discounts, this is no longer the case.

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Ammunition as explosives followup

This last Monday, July 9th, the Occupational Safety and Health Administration (OSHA) extended the comment period for their latest round of brilliant stupidity... classifying ammunition as explosives. (Mentioned before in this weblog entry.)

Officially known as Docket No. OSHA-2007- 0032, this proposal will quickly become a very big problem if it is not shut down before the mainstream media gets wind of it. I can already see the people who have never handled a firearm, let alone seen a real one, come out in a big ignorant celebrity studded show of support. After all, a .22 rimfire and a block of C-4 both go "bang", right? Just at different volumes!

I am still convinced this is an attempt at backdoor regulation of ammunition and, by proxy, firearms. I have yet to see the round of ammunition that can level a building, destroy a tank, or take down a wall of reinforced concrete and brick. That is what explosives do. Explosives are volatile, very temperamental, and must be handled with extreme care. Ammunition needs to be pointed at something to destroy it. Explosives work in a wide area and do not work on a direct linear path.

Another big difference between ammunition and explosives? Time. Old ammunition can be packed tightly in a box and left alone for years and never discharge. Old ammunition can be shipped anywhere in the world with a civilian carrier service and never discharge a single round. Old ammunition can be picked up casually and tossed into a jacket pocket with dozens of similar rounds and never discharge. Try any of those things with sticks of old dynamite.

The only time ammunition discharges by itself is when it is on fire. But everything tends to discharge when on fire. Passenger cars, cans of Cheez Whiz, deodorant, aerosol cans... if its under pressure, or has flammable contents sealed inside of it, its an explosive device when heated enough.

OSHA knows all of these things. So why the new regulation after all this time?

According to the main opposition link at

http://www.nraila.org/Legislation/Federal/Read.aspx?id=3151&issue= ,

you can submit comments on Docket No. OSHA-2007- 0032 by any of the following methods:

• Electronically: You may submit comments and attachments electronically at http://www.regulations.gov, which is the Federal eRulemaking Portal. Follow the instructions on-line for making electronic submissions.

• Fax: If your comments, including attachments, do not exceed 10 pages, you may fax them to the OSHA Docket Office at (202) 693-1648.

• Mail, hand delivery, express mail, messenger or courier service: You must submit three copies of your comments and attachments to:

OSHA Docket Office, Docket No. OSHA-2007-0032
U.S. Department of Labor, Room N-2625
200 Constitution Avenue, NW.
Washington, DC 20210

telephone (202) 693-2350 (OSHA"s TTY number is (877) 889-5627).

Please take a moment and let these bozos people at OSHA know what you think. Even though the comment period now ends on September 10, 2007, the more people that voice their opposition now, the better the chances this thing will be shut down early.

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Project ChildSafe and free locks

Project ChildSafe is a website that says it is "The Nation's Largest Firearm Safety Education Program". What caught my attention about the website are the safety kits they are distributing for free.

According to the website, each of the "firearms safety kits include a safety brochure that covers a variety of options for firearms storage and a free cable-style gun lock."

A free gun lock. That's great!

When you are on the Project ChildSafe website, clicking on the state you live in will show you where you can pick up one of these free safety kits or where to request a kit from. The kits contain instructions on how to use the gun lock as well as basic safety rules and guidelines for handling a firearm.

The website is located at http://www.projectchildsafe.org/

Take a moment to see how to secure your firearm if you have not done so already!

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Ammunition as explosives?

In another fit of ignorance, The Occupational Safety and Health Administration (OSHA), has come up with a proposal to completely re-classify ammunition... as explosives.

Quoting from the NRA's website, "The Occupational Safety and Health Administration (OSHA) has proposed new rules that would have a dramatic effect on the storage and transportation of ammunition and handloading components such as primers or black and smokeless powder. The proposed rule indiscriminately treats ammunition, powder and primers as “explosives.”"

The proposal continues to stipulate a prohibition on "delivery drivers from leaving explosives unattended—which would make it impossible for delivery services such as UPS to deliver ammunition or gun powder" and also "require evacuation of all “facilities containing explosives”—even your local Wal-Mart—during any electrical storm."

I am personally opposed to any kind of backdoor regulation, which to me is what this proposal seems to be designed for. There are no specifics in what needs to be regulated in this proposal, and no reasons why there needs to be a change in the existing laws governing ammunition and powder sales. So why make this a law?

Mandating the evacuation of facilities containing explosives is a great way to kill off any ammunition sales at any major retailer too. No manager of any store is going to stock ammunition if it means they have to close their entire store during a electrical storm. And no major retailer is going to want to face the wrath of the federal government if they accidentally disobey the law a few times.

And what would happen to those people who keep a box of ammunition at home for their firearms? Are they going to be classified as the same kind of people who have access things like C-4 or hand grenades? There is a slight difference between them!

You can see the whole article and proposal at

http://www.nraila.org/Legislation/Federal/Read.aspx?id=3145

The NRA has a link to the OSHA website and how and where to comment on this proposal. Even if you put in a simple one paragraph comment to OSHA, they need to know there is no need for this proposal to become law, and even less of a need for proposals like this in the future.

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