Definition:

A primer is a device for igniting the powder charge in a modern cartridge of centerfire ammunition. Cylindrical in shape, and inserted into a pocket built into the center of the base (or head) of a cartridge case in centerfire rifle, handgun, and shotgun ammunition. When struck in the center by a firing pin, the primer produces a spark or flame within the cartridge case, which ignites the powder charge, thus driving the projectile(s) (bullet or shot charge) downrange.


How it's Made

The primer is a cup made of a fairly soft, malleable metal. Priming compound is placed into the open end of the cup, and a small separate metal piece known as the anvil is then inserted atop the priming compound. The firing pin crushes the compound between the cup and anvil, and that crushing force causes the compound to ignite.

Rimfire, too?

Primer may also refer to the priming compound in the rim of rimfire ammunition, which serves the same purpose as a centerfire primer (igniting the powder charge). This is in the minority, however, and in shooting texts primer most often refers to a centerfire primer as described above.

Pronunciation: pry mer (noun)

Examples: The firing pin struck the primer, igniting the powder charge.