Ammunition University

Often times we get asked the question “What is the difference between a centerfire and a rimfire cartridge.”

Apart from the obvious difference in sizes and shapes, the primary technical difference between these two is the design of the cartridge case specifically related to the location of the priming mixture, which is the impact-sensitive substance that produces the spark to ignite the powder inside the casing.

In a centerfire cartridge (rifle, pistol or shotshell), the priming compound is located inside a small metal cup called a primer, which is made separate from the casing. The cup is inserted into a hole in the center of the base of the cartridge. The firing pin strikes the primer crushing it against an internal anvil to produce the spark. Centerfire cartridge brass is harder than a rimfire cartridge, because only the primer cup needs to be soft.  Centerfire rifle and pistol cartridges are available in numerous calibers with different bullet styles, weights, and velocities. Centerfire shotshells are available in numerous gauges with different shot sizes, projectiles, load weights and velocities. To determine the proper centerfire rifle, pistol and shotshell configuration you should select the cartridge based on what kind of shooting you do and what game you are pursuing.

In a rimfire cartridge, the priming compound is located inside the hollow rim of the cartridge case. The firing pin crushes the rim against the chamber mouth to fire the cartridge. Rimfire cases are made of softer brass so that the firing pin can crush the rim.
The most common rimfire cartridge in use today is .22LR, popular for target shooting and pest control. Due to low cost and low recoil it is probably the most popular cartridge in the world. Another popular rimfire caliber is the .22 WMR, which is used for both target shooting and small game hunting.

NOTE: Ammunition may perform differently in different firearms. What shoots well in your specific firearm may not be the best choice for another firearm of the same make and model. To maximize the full potential of your firearm, try various Sellier & Bellot ammunition configurations to determine which specific round performs best in your firearm.