Usually the first gun kids shoot is a .22lr of some kind. The little pill sized .22 caliber cartridges with stubby little bullets. These little straight walled cartridges may seem just like they’re bigger brothers but the powder, bullet and brass is about where the similarities end. Rimfire cartridges first came about in 1845 and were the very first self-contained cartridges, and astonishingly they haven’t changed much since the original patent was filed.
Centerfire ammunition has a self-contained primer pressed into the rear of the cartridge. The change to fulminated mercury based primers to ignite cartridges allowed for a whole new world of power and design. The ability to push more than small 6mm and 5mm projectiles lead to the use of self-contained firearms for defense and hunting.
Self-contained primers were ahead of their time when first invented because metallurgy needed to catch up with the potential for power and pressure. This change to the new design allowed for a more consistent temperature and starting charge for the powder and more importantly more reliable ignition.
Suddenly a new frontier of firearm design opened up with the new primers. Huge powder charges could be burned and large projectiles could be pushed at high velocities. Shotguns could now be loaded quickly for market hunters, armies carried more reliable, more powerful rifles and mass production of trap door rifles started.
The change to a small primer in the rear of the cartridges created more than just a reason to buy a new rifle. One could argue the switch was just as, if not, more important than the switch to smokeless powder at the turn of the 20th century.
For a bit of history on the rimfire and centerfire check out this video and then be sure to read on for more details...
Rimfire vs. Centerfire Ignition
As said earlier, the main difference between rimfire and centerfire ammunition is the primer at the rear of the cartridge. The primer on a .22lr is built into the case rim on the rearmost portion of the case. A centerfire ignition has a self-contained primer that can be replaced. The primary advantage of this primer is the ability to burn large amounts of powder.
Because the case wall doesn’t need to be struck, only the primer gets hit, the case can be made thicker and stronger in a centerfire cartridge. The primer creates a concentrated jet of heat that ignites the powder evenly and burns completely. Most rimfire ammo burns unevenly and leaves much more powder residue because of this uneven burning.
Image by BBODO
The more even burn and a stronger case leads to a bigger charge of powder and a faster, bigger bullet with a flat trajectory and bone crushing power. Rimfire just cannot compete in the power department because of the ignition system. The .17wsm being one of the strongest rimfire cartridges of all time is still a pip squeak compared to even small centerfire rounds like 9mm parabellum.
Rimfire vs Centerfire Case Design
Rimfire cartridges all have one essential design; they must have a case rim too compensate for lack of a primer. This rim is what allows the gun to fire by igniting the primer compound in the edges of the case and setting off the powder charge. The rim around the base of the case also creates difficult feeding issues that must be solved in creative ways. Examples of this are Ruger’s rotary magazine and the extreme curvature of the Ruger BX25 magazine.
Centerfire cases are much thicker and usually made of high quality brass. Only centerfire brass is reloadable. Until recently there were no bottleneck cartridges that were rimfire and it was rare to see straight walled centerfire cases outside of pistol cartridges.
Rimfire vs. Centerfire Firearms Design
Single shot design between rimfire and centerfire guns isn’t different only semi-automatic guns differ. While most semi-automatic guns are reloaded using the force generated by the escaping gases most semi-automatic rimfire guns use the recoil force of the firearm.
This is most seen in rimfire pistols. They have beefy slides to help absorb the recoil and cycle the gun. Whereas the tilting breech design in 99% of combat centerfire pistols, relies on recoil springs and a tilting barrel design to rack the slide and load the weapon.
This allows the guns to be extremely simple, no tilting or rotating barrels to worry about. The straight blowback design has inherent accuracy, with its fixed barrel. Compared to bolt and lever action centerfire guns, rimfire guns have little advantage because of the design similarities of the rifles.
When considering rimfire vs centerfire accuracy also take into account rimfire ammo, because of the low powder charges it has very little recoil, noise and muzzle flash. Everyone shoots better with less recoil and less distraction room the shooting fundamentals. That is part of the reason it is so much fun to shoot rimfire cartridges.
Rimfire vs. Centerfire for Hunting
Rimfire guns should only really be used for small game. Some people advocate the use of .22lr or .22 magnum for hunting hogs or coyotes, however, many agree this is irresponsible. While a .22 caliber bullet at the exact right spot will kill anything, the problem is the margin for error. The spot you need to shoot a hog with to make a clean kill is about the size of a ping pong ball.
The other problem is the construction of the bullets used in manufacturing rimfire ammo. Often pure lead, or very soft alloys are used because of the intended use of the round; violent expansion on small game. Rimfire ammo isn’t reloadable so we’re stuck with the bullets the manufacturer chooses. This is much like the problem water fowl hunters face with the lead vs. steel shot debate; being forced to use an inferior product at the hands of high authority.
This small ping pong ball sized target is not just a target. When hunting, your targets are living animals. Choose a weapon that that will make a reliable kill out to the range you plan on hunting and use a well-constructed bullet that will penetrate deep enough to destroy vital organs.
This is not to say that all centerfire rounds are capable of taking game. The smallest pistol cartridges designed with centerfire primers are much more powerful than a .22 magnum and still aren’t suitable for taking game larger than squirrels and rabbits.
Rimfire rounds are champions of the dinner table. Using their lightweight, virtually non-recoiling rifles to take small game is a great way to introduce young hunters to hunting and wildlife management.
Side note: You may also be interested in learning about using optics for Rimfire rifles as these will be different than scopes and sights for centerfire. Check out our choices for the best rimfire scopes.
The Verdict
Using rimfire cartridges can be great for a lot of things but sub-par for other jobs. If used for taking game, it needs to be relegated to small light game at relatively close ranges. Rimfire cartridges fit in where a centerfire is too big but a firearm is desired. In sporting circles, the ubiquitous .22lr is used for everything from formal target shooting to trick shots at matches and cards. The final reason why rimfire is popular despite its short comings and that’s cost.
Rimfire ammo is the only group of rounds where you can burn 1,000 rounds in a day and not cringe when you check your wallet.
Rimfire cartridges are fun, easy to shoot and versatile rounds despite being largely inferior to centerfire ammo.
Hopefully this has helped understand the differences between rimfire vs centerfire cartridges.
