Editing Centerfire ammunition (section)

===Berdan primer===
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 {{US patent|53388}}. A small copper cylinder formed the shell of the cartridge, and the primer cap was pressed into a recess in the outside of the closed end of the cartridge opposite the bullet. In the end of the cartridge beneath the primer cap was a small vent-hole, as well as a small teat-like projection or point (this was to be known as an anvil later on) fashioned from the case, such that the firing pin could crush the primer against the anvil and ignite the propellant. 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.

Difficulties arose in practice because pressing in the cap from the outside tended to cause a swelling of the copper cartridge shell, preventing reliable seating of the cartridge in the chamber of the firearm. Berdan's solution was to change to brass shells, and to further modify the process of installing the primer cap into the cartridge, as noted in his second Berdan Primer patent of September 29, 1868, in {{US patent|82587}}. 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 "primer pocket" of a Berdan-type cartridge case, where they fit slightly below flush with the base of the case.  Inside the primer pocket is a small bump, the "anvil", that rests against the center of the cup, and usually two (or more) small holes by the sides of the anvil, which allow the flash from the primer to reach the interior of the case. Berdan cases are reusable, although the process is rather involved.  The used primer must be removed, usually by [[hydraulic]] pressure, pincer, or lever that pulls the primer out of the bottom. A new primer is carefully seated against the anvil, and then the powder and a bullet are added.

====Centered single-hole primer====
From the 1880s to the 1940s, many smaller European armies were reloading their ammo for economical reasons, and for that reason they adopted the system known as either Austrian or after the George Roth factory in Vienna which patented it in 1902<ref>{{patent|AT|15483B}}, diagram at [https://forum.cartridgecollectors.org/t/austrian-berdan-primers/13116/23]</ref> even though it was known from the early-to-mid 1880s, where the anvil had a single fire hole right at its center.