Knowing if your gun is centerfire or rimfire is very important. You might be thinking, why? Because every gun is chambered for a specific type of cartridge. Improper ammunition might result in injury.
Here is the primary question, "How to tell if your gun is rimfire or centerfire?" and you are going to find the answer in this article. First, let's get a basic understanding of what a cartridge is and how does everything works.
A casing of metal or plastic enclosing a projectile (bullet) and ignition device is called a cartridge. On some firearms, the barrel is stamped with the type of cartridge required for shooting. But sometimes, there is no such stamp which can cause confusion. In less expensive guns, the chamber is often not cut to match the cartridge diameter. If a rimfire type of cartridge is chambered in a gun that was built for centerfire cartridges, it can often damage the firearm and could injure you.
Rimfire means that the firing pin will strike the rim of a bullet when it is fired. A casing with a primer located in its center base contains a percussion cap within an impact-sensitive chemical compound. The force from the impact ignites this compound which detonates and propels flame through small vent holes causing it to rapidly ignite the powder charge. In recent decades, these have been made with polymer or aluminum parts because metal can cause false-safe malf where stray particles or humidity might make the primer inert.
The rimfire cartridge is much cheaper to make because it uses less brass and can be reloaded with relative ease compared to other cartridges. It also allows gun manufacturers to offer less expensive options for both rifles and handguns. Rimfire cartridges are usually low-powered though the .22 caliber long rifle (LR) version has become an exception to that rule in recent years, becoming popular as a small game hunting cartridge for its high velocity and flat trajectory. The .17 HMR round is based on the necked down .22 LR case, while still offering great velocities making it ideal for small-game rodents at 100+ yards distant. However, these rounds can sometimes get stuck inside of a barrel without anyone noticing, especially with rifles that have a deep magazine well.
When it comes to centerfire cartridges, the primer is located in the center of the casing and features a small, impact-sensitive explosive compound within the rim itself. The firing pin crushes this material which causes a flame to light off all around as opposed to just at one opening like with rimfires. This makes it more reliable because the cartridge requires no outside influence such as humidity or debris for it to work properly. Bullets feature a lead core surrounded by harder metals such as copper or steel jackets, depending on the requirements of the cartridge – making them much stronger than their rimfire counterparts – thus enabling higher muzzle velocities and greater effective range.
Centerfire casings can be reloaded but the resizing process requires that they be trimmed to length or else the case could become too short or fall into place in between the bolt face and barrel breech leaving it stuck. Another important aspect is that centerfire cartridges are much less susceptible to damage than rimfires. Generally speaking, these two factors alone make converting a gun from one type of cartridge to another unfeasible so you need to take extra care when handling firearms chambered for either .22 LR rimfires, .17 HMR rounds, 9mm Parabellum handguns, etc.
Difference between Centerfire and Rimfire Cartridge:
There are 2 types of cartridges rimfire and centerfire. Rifles, shotguns, and handguns mostly use centerfire cartridges. In centerfire, the primer is located in the center of the cover's bottom side. Such arrangement creates a bigger explosion and can propel bigger bullets with more precision.
As the name rimfire suggests, the primer, in this case, is located in the bottom edge (rim) of the metal casing. When firing a rimfire cartridge, the pin crushes the rim.
You can easily differentiate between them by observing the bottom side of the cartridge. Centerfire will have round primer in the center, while the rimfire cartridge's tail will be plain.
Another method to distinguish between the two is by breaking them open. If you can break open your cartridge, it's centerfire; if not, it's rimfire.
Rimfires are often cheaper than centerfires because they're made of more affordable material and don't require trimming after reloading. These cartridges also allow manufacturers to produce less expensive rifles and handgun options for their customers. Rimfire cartridges are commonly low-powered though the .22 LR version has become an exception to this rule in recent years becoming popular as a small game hunting cartridge for its high velocity and flat trajectory of about 300 yards (275 m). The .17 HMR round is based on a necked-down .22 LR case while still offering great velocities making it ideal for small-game rodents at 100+ yards distant. However, these rounds can get stuck inside of a barrel without anyone noticing, especially with rifles that have a deep magazine well.
Centerfire casings can be reloaded but the resizing process requires they be trimmed to length or else the case could become too short or fall into place in between the bolt face and barrel breech leaving it stuck. Another important factor is that centerfire cartridges are much less susceptible to damage than rimfires which makes converting a gun from one type of cartridge to another unfeasible so you need to take extra care when handling firearms chambered for either .22 LR rimfires, .17 HMR rounds, 9mm Parabellum handguns, etc.
Determining if your gun is chambered for rimfire or centerfire
Even if you can't identify all the different cartridges out there, you can determine what cartridge your weapon needs by looking at it. To use this method, first, remove the magazine, then ensure that your gun is unloaded. After all the precautionary measures, you can have a look at the bolt face.
Bolt’s face allows the pin to strike the back of the bullet so you can easily observe if the pinhole is at the center; it means the gun is a centerfire. But if the pin whole is towards edge or off-center, that means your weapon is chambered for rimfire. The best way to eliminate any chance of confusion is to make sure you don't mix up your firearms. For example, you should never insert a rimfire rifle cartridge into a centerfire pistol or vice versa.
How can I tell if my gun chamber is .22LR when the ammunition is stuck in the barrel?
If you're out shooting and come across your cartridge stuck in your barrel, especially if it's an unfamiliar weapon, here are some steps you can take to determine what kind of cartridge/weapon you have:
- Check for any identification markings on the barrel or receiver that would identify the manufacturer and model. If there are none, stop! Don't do anything else until you get help from someone who knows better than yourself.
- Determine if the barrel is steel or alloy (usually aluminum). Using your fingernail, scrape along the length of the barrel. If it scratches easily, you know the material is soft enough for somebody to drill out using a drill press at home. So you should go get help.
- Look directly down the bore; if the cartridge appears centered in the bore then it's likely that the firearm was intended to fire centerfire cartridges and not rimfire cartridges. You might even find numbers indicating caliber stamped on one side of the gun barrel frequently near where you're looking into.
- Get an empty shell casing that's already been shot from your weapon so you can push it back through your chamber with maximum pressure to check for ejector markings. You should do this instead of trying to extract the cartridge from the chamber yourself because you could accidentally damage the extractor, extractor spring, extractor pin, extractor claw, or extractor plunger and one of those parts will need to be replaced if they got damaged during your attempt. If you have an empty shell casing that's been shot from your weapon, push it back into the chamber until you feel resistance at which point stop – don't force it in any further – then look closely just below where the bolt face is located. If there are marks on the rim of a spent round that matches up with a mark left by a firing pin then your firearm was chambered for centerfire calibers and not rimfire.
Considerations when dealing with rimfires
Keep in mind that not all modern firearms are chambered for centerfire cartridges because some owners prefer to use cheaper ammo. When it comes to handguns, you should look closely at the top of a magazine which typically has a marking indicating a house brand or a patent number will be printed there and sometimes even the caliber designation as well if the handgun is for target shooting or competition. For example, Springfield Armory 1911s almost always have one on both sides of the magazine since they usually come with flush-mounted magazines as standard equipment rather than grip panels for loading rounds into by hand after breaks during competitions involving .45 ACP semi-automatic pistols. In rifles where changing calibers is quite common, the caliber designations will typically be included on each individual round within a given box of ammo to avoid confusion during the reloading process after owners fire their weapon.
But again, you should never mix up your firearms because even a single mistake could result in catastrophic failure.
Keep in mind that some manufacturers have been known to produce both centerfire and rimfire weapons simultaneously so you might find a model listed as a .22LR but with slightly different exterior dimensions than other models chambered for .22LR cartridges. For example, there's no such thing as a Colt M1911 chambered for 9mm (.38 Super) while also being sold under the designation of Colt M1911A1 which has been produced since 2011 by Colt Defense LLC. There's also no such thing as a Colt M1911A1 chambered for .38 Special (and not 9mm) which has been produced since 2011 by Colt Defense LLC.
When it comes to newer issues, you might find the manufacturer and model designation stamped on the receiver instead of appearing on the barrel because markings placed there can be used as part of an effort to prevent counterfeiting - especially if your firearm is actually worth more than you think it is.
Using the centerfire/rimfire distinction to figure out whether or not a firearm is semi-automatic or completely legal
In all cases where you have concerns, don't shoot it. It's also important that everyone in your house knows how to tell if a gun is chambered for centerfire or rimfire cartridges because this knowledge can affect firearms laws. In an emergency situation, consider calling 911 and letting them know what's going on but ONLY after you think you've exhausted every other option available including consulting an attorney who might specialize in criminal law so they can help protect your rights without breaking laws themselves. But keep in mind that any self-defense incident will affect more than just yourself so prepare everything necessary before acting because it might be too late to make any changes after the fact.
Ammunition available in both centerfire and rimfire calibers might be restricted in some jurisdictions so you should contact your local law enforcement agency and find out what's legal and what's not in your area before buying anything online or in person. Also, keep in mind that using a firearm that is chambered for centerfire cartridges might result in increased charges if convicted when compared with using ammunition designed for use by handguns which are typically designed with shorter barrels (and therefore less accuracy) specifically to reduce chances of injuring innocent bystanders during self-defense situations involving handguns.