A centerfire cartridge is a cartridge with a primer located in the center of the cartridge case head. Unlike rimfire cartridges, the primer is a separate and replaceable component, centerfire cartridges have supplanted the rimfire variety in all but the smallest cartridge sizes. The stronger base of a cartridge is able to withstand higher pressures which in turn give a bullet greater velocity. Larger caliber rimfire cartridges require greater volumes of priming explosive than centerfire cartridges, reducing the amount of priming explosive would reduce the reliability of rimfire cartridge ignition, and increase the probability of misfire or dud cartridges. Economies of scale are achieved through interchangeable primers for a variety of centerfire cartridge calibers. The expensive individual brass cases can be reused after replacing the primer, gunpowder, the forward portion of some empty cases can be reformed for use as obsolete or wildcat cartridges with similar base configuration. Modern cartridges larger than.22 caliber are mostly centerfire, actions suitable for larger caliber rimfire cartridges declined in popularity until the demand for them no longer exceeded manufacturing costs, and they became obsolete. An early form of ammunition, without a percussion cap, was invented between 1808 and 1812 by Jean Samuel Pauly. This was also the first fully integrated cartridge, true centerfire ammunition was invented by the Frenchman Clement Pottet in 1829. However, Pottet would not perfect his design until 1855, the centerfire cartridge was improved by Benjamin Houllier, Gastinne Renette, Charles Lancaster, George Morse, Francois Schneider, Hiram Berdan and Edward Mounier Boxer. The identifying feature of centerfire ammunition is the primer which is a cup containing a primary explosive inserted into a recess in the center of the base of the cartridge. The firearm firing pin crushes this explosive between the cup and an anvil to produce hot gas and a shower of incandescent particles to ignite the powder charge, Berdan priming is less expensive to manufacture and is much more common in military-surplus ammunition made outside the United States. Berdan primers are named after their American inventor, Hiram Berdan of New York who invented his first variation of the Berdan primer and patented it on March 20,1866, in U. S. A small copper cylinder formed the shell of the cartridge, and this system worked well, allowing the option of installing a cap just before use of the propellant-loaded cartridge as well as permitting reloading the cartridge for reuse. S. Berdan primers have remained essentially the same functionally to the present day, Berdan primers are similar to the caps used in the caplock system, being small metal cups with pressure-sensitive explosive in them. Modern Berdan primers are pressed into the pocket of a Berdan-type cartridge case. Inside the primer pocket is a bump, the anvil, that rests against the center of the cup. Berdan cases are reusable, although the process is rather involved, the used primer must be removed, usually by hydraulic pressure or a pincer or lever that pulls the primer out of the bottom
Two rounds of .357 Magnum, which is a centerfire cartridge. Notice the circular primer in the center of the cartridge.
The primer of this unfired cartridge has been sealed with red lacquer to prevent oil or moisture from reaching the powder charge and priming explosive.
Large (top row) and small (bottom row) pistol cartridge Boxer primers. (L–R fired, unfired, and inside view.) The tri-lobe object inside the primer is the anvil.
The same cartridge (.45 ACP shown here) can have different primer sizes depending on manufacturer.