Centerfire ammunition
U.S. General Stephen Vincent Benét developed an internally primed center-fire cartridge that was adopted by the U.S. Army Ordnance Department starting in 1868, ultimately being phased out in the mid 1880s.
[4] The centerfire cartridge was improved by Béatus Beringer, Benjamin Houllier, Gastinne Renette, Smith & Wesson, Charles Lancaster, Jules-Félix Gévelot, George Morse, Francois Schneider, Hiram Berdan and Edward Mounier Boxer.
The stronger base of a centerfire cartridge is able to withstand higher chamber pressures which in turn gives bullets greater velocity and energy.
While centerfire cartridge cases require a complex and expensive manufacturing process, explosive handling is simplified by avoiding the spinning process required to uniformly distribute priming explosive into the rim because of uncertainty about which angular segment of a rimfire cartridge rim will be struck by the firing pin.
Reducing the amount of priming explosive will greatly diminish the ignition reliability of rimfire cartridges, and increase the probability of a malfunction such as a misfire or hang fire.
Handloading reuse is an advantage for rifles using obsolete or hard-to-find centerfire cartridges such as the 6.5×54mm Mannlicher–Schönauer, or larger calibers such as the .458 Lott, for which ammunition can be expensive.
The forward portion of some empty cases can be reformed for use as obsolete or wildcat cartridges with similar base configuration.
Actions suitable for larger caliber rimfire cartridges declined in popularity until the demand for them no longer exceeded manufacturing costs, and they became obsolete.
The identifying feature of centerfire ammunition is the primer which is a metal 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.
And while the primer has one additional step needed during the manufacturing process, the cartridge case is simpler to make, use, and reload.
Rifle, large and magnum primers increase the ignition energy delivered to the powder, by supplying a hotter, stronger and/or longer-lasting flame.
All modern shotgun shells (excluding specialized .22 caliber rimfire "snake loads" or birdshot cartridges) are centerfire.
Shotgun primers are also used as a replacement to the percussion cap ignition system in some modern black-powder firearms, and in some cases as the actual cartridge, notably the 6mm Pipet.
Sensitive priming compounds have claimed many lives including the founder of the famous British Eley ammunition firm.
A misfire would result if the priming compound either failed to react to the firing pin fall or extinguished prior to igniting the powder charge.
In extreme cases, the delay might be sufficient to be interpreted as a misfire, and the cartridge could fire as the action was being opened or the firearm pointed in an inappropriate direction.
Mercury coated the interior of brass cases with smokeless powder loads, and the higher pressures of smokeless powder charges forced the mercury into grain boundaries between brass crystals where it formed zinc and copper amalgams weakening the case so it became unsuitable for reloading.
The United States Army discontinued use of mercuric priming mixtures in 1898 to allow arsenal reloading of fired cases during peacetime.
The PA-101 primers developed at Picatinny Arsenal used about 50% lead styphnate with lesser amounts of barium nitrate, antimony trisulfide, powdered aluminum and a tetrazine compound.
[31] Manufacturers subsequently offered more powerful magnum primers for uniform ignition of civilian long-range or big-game cartridges with significantly greater powder capacity than required for standard infantry weapons.
