So, what is the main difference between centerfire and rimfire ammunition? In centerfire ammunition, the firing pin hits the center of the cartridge to ignite the round. Whereas, in rimfire ammunition, the firing pin has to hit the rim of the cartridge in order to ignite the round. Hence the names centerfire and rimfire.
That didn’t seem too complicated right? It’s really not, but there are more characteristics that make each one of these cartridges different because of their inner workings and primer location. We will talk about this more later on. For now a little background information on the basic components of a cartridge.
A cartridge, also known as a round, is not actually a bullet. Instead, it contains the bullet and the mechanism to help fire it. Working our way from the outside in, we have the shell that encases the components. Starting at the back and moving forward we have the primer, powder/propellant, and last but not least the bullet.
Like in the picture depicted below, the primer is a large and cylindrical device located right in the center on centerfire rounds such as the common 9MM. With a rimfire round, the primer compound is located all around the rim of the casing(or shell) instead of in the middle.
If you have ever shot a rifle, maybe in the backyard with dad when you were little, you may have shot a rimfire cartridge and didn’t realize it. One of the most common rifle calibers for older rifles is a .22 LR, which is a rimfire cartridge. Even modern-day rifles still use this caliber round, but with technological advances, we’ve come a long way and it’s not as common as it used to be.
Speaking of technology and the age of rimfire cartridges let’s talk a little bit about the history of rimfire and centerfire ammo and how far we have advanced with technology.
Did you know that centerfire rounds were not the first type of ammo to be created? In 1845 a man named Louis-Nicholas Flobert created the first rimfire round. At first, it was just a percussion cap with a bullet on top, but it slowly developed into what we know today as the rimfire cartridge.
In the early stages, rimfire rounds had a low muzzle velocity due to the inherent design of the round. In 1857 the .22 Short was developed for Smith & Wesson’s first revolver. Just 30 years later in 1887 the .22 LR was developed. It had a higher muzzle velocity than the previous rounds making it suitable for hunting and target practice.
With time, larger caliber rounds like .38 rimfire and .41 Short were created as rimfire but they were quickly replaced by centerfire rounds.
In the early 1800s, a version of the centerfire round was created but it was not until the mid-1800s that the design most similar to what we now know as centerfire was created.
Rather than the primer being a cap at the base of the bullet it was self contained and inserted into the center of the round at the base. Using mercury based primers allowed for more powder to be inserted into the rounds, and more powder means bigger bullets. But this posed a problem for designers. The casing wasn't strong enough to contain this newfound power. Eventually, they improved the casing and centerfire rounds rapidly took over the market.
Centerfire ammunition allowed shotguns to be reloaded quicker and soldiers had more powerful and accurate rifles. This new cartridge opened up a whole new world for manufacturers.
This picture below depicts where the firing pin strikes each type of round. You are viewing it from the bottom of the cartridge.
From the early years of firearms when gunpowder and ammunition needed to be loaded separately to today where the bullet and gunpowder are encased in one tiny shell, technology has continually advanced. It has become easier to own a gun, and ammunition like rimfire and centerfire makes it easier to load and operate firearms.
What caliber is rimfire and centerfire ammo?
You might be wondering which one you should be using. The answer is simpler than you probably think. There are distinct calibers created as centerfire and rimfire cartridges. Rimfire cartridges are typically smaller and most commonly used for target practice and small game hunting, whereas centerfire is used for pretty much everything else.
The most common rimfire round is going to be the .22LR. Even with centerfire being more popular the .22LR is the most sold round of them all. It is relatively inexpensive and is a starting round for many people. Some other rounds that use rimfire cartridges are .22 Short, .22 WMR, .17 HM2, and the .17 HMR.
9mm, .45 ACP, and .38 Special among many others make up the vast array of remaining calibers. Centerfire rounds are going to be the larger calibers because of their design; they are able to hold more powder than a rimfire round.
More on rimfire vs centerfire
There is a lot of information that can be found on centerfire and rimfire ammunition, but there are just a few more pieces of information we wanted to give you before we close out this article.
- Which one is more reliable: centerfire or rimfire? Centerfire is inherently more reliable and stable. This is because the primer is self contained. While a misfire or dud can happen with any round it is more likely to happen with rimfire ammo.
- Does centerfire or rimfire have more power? Centerfire is going to have more power because it is able to hold more powder with bigger bullets. Rimfire has a thinner casing and is primarily for smaller caliber rounds.
- Is centerfire or rimfire more expensive? Rimfire ammo is much cheaper to manufacture than centerfire. It has a thin casing with a flattened primer. .22LR rounds can be found for less than 10 cents apiece whereas the comparable .223 Remmington ranges from 25-40 cents apiece depending on the current supply and demand.
Let’s review. In centerfire ammunition, the firing pin hits the round in the center where the primer is located. In rimfire ammunition, the firing pin strikes the rim of the round because the primer is located all around the rim of the casing. Rimfire ammo is cheaper and more common than centerfire but is only available in smaller calibers. Centerfire is going to be more popular for modern pistols and is more reliable than rimfire.
Overall they are both common types of ammunition and you may find you use one more than the other based on what firearms you own or you may find you use both.
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