Editing Centerfire ammunition (section)

===Boxer primer===
[[file:Primers.jpg|thumb|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.]]
[[file:.45 ACP primers.jpg|thumb|The same cartridge ([[.45 ACP]] shown here) can have different primer sizes depending on manufacturer.]]

Meanwhile, Colonel [[Edward Mounier Boxer]], of the [[Royal Arsenal]], Woolwich, England, was working on a primer cap design for cartridges, patenting it in England on October 13, 1866, and subsequently received a U.S. patent for his design on June 29, 1869, in {{US patent|91,818}}.

Boxer primers are similar to Berdan primers with one major difference, the location of the anvil. In a Boxer primer, the anvil is a separate stirrup piece that sits inverted in the primer cup and provides sufficient resistance to the impact of the firing pin as it indents the cup and crushes the pressure-sensitive ignition compound. The primer pocket in the case head has a single flash-hole in its center. This positioning makes little or no difference to the performance of the cartridge, but it makes fired primers vastly easier to remove for [[Handloading|reloading]], as a single, centered rod pushed through the flash hole from the open end of the case will eject the two-piece primer from the primer cup. A new primer, anvil included, is then pressed into the case using a reloading press or hand-tool. Boxer priming is universal for US-manufactured civilian factory ammunition.

Boxer-primed ammunition is slightly more complex to manufacture, since the primer is in two parts in addition to the pressure-sensitive compound, but automated machinery producing the more complex primers by the hundreds of millions has eliminated that as a practical problem. And while the primer has one additional step needed during the manufacturing process, the cartridge case is simpler to make, use, and reload.

Early primers were manufactured with various dimensions and performance.  Some standardization has occurred where [[economies of scale]] benefit ammunition manufacturers. Boxer primers for the United States market come in different sizes, based on the application. The types/sizes of primers are:

* 0.175" (4.45&nbsp;mm) diameter ''small pistol'' primers, and a thicker or stronger metal cup ''small rifle'' version for use with higher pressure loadings in weapons with heavy firing pin impact.
* 0.209" (5.31&nbsp;mm) diameter primers for [[shotgun shell]]s and modern inline [[muzzleloader]]s, using a Boxer-type primer factory-assembled inside a tapered, flanged brass cup.
* 0.210" (5.33&nbsp;mm) diameter ''large rifle'' primers, and a thinner or softer metal cup ''large pistol'' version for use with lower pressure loadings in weapons with light firing pin impact. Large rifle primers are also 0.008" taller than large pistol primers.<ref>{{cite web|title=FAQ|url=http://www.cci-ammunition.com/education/faqs.aspx|access-date=27 March 2014|url-status=live|archive-url=https://web.archive.org/web/20140327053515/http://www.cci-ammunition.com/education/faqs.aspx|archive-date=27 March 2014}}</ref><ref>{{cite journal|last=Calhoon|first=James|title=Primers and Pressure|journal=Varmint Hunter|date=October 1995|url=http://www.jamescalhoon.com/primers_and_pressure.php|url-status=live|archive-url=https://web.archive.org/web/20150107135641/http://www.jamescalhoon.com/primers_and_pressure.php|archive-date=2015-01-07}}</ref>
* 0.315" (8.00&nbsp;mm) diameter [[.50 BMG]] primers, used for the .50 Browning Machine Gun cartridge and [[wildcat cartridge|derivatives]]
Examples of uses:
* [[.38 Special]], small pistol standard
* [[.357 Magnum]], small pistol magnum
* [[.45 Colt]], large pistol standard
* [[.50 Action Express]], large pistol magnum
* [[.223 Remington]], small rifle standard
* [[.357 Remington Maximum]], small rifle magnum
* [[.308 Winchester]], large rifle standard
* [[.338 Lapua Magnum]], large rifle magnum

Primer size is based on the primer pocket of the cartridge, with standard types available in large or small diameters.  The primer's explosive charge is based on the amount of ignition energy required by the cartridge design; a standard primer would be used for smaller charges or faster-burning powders, while a magnum primer would be used for the larger charges or slower-burning powders used with large cartridges or heavy charges. Rifle, large and magnum primers increase the ignition energy delivered to the powder, by supplying a hotter, stronger and/or longer-lasting flame. Pistol cartridges often are smaller than modern rifle cartridges, so they may need less primer flame than rifles require. A physical difference between pistol and rifle primers is the thickness of the primer's case; since pistol cartridges usually operate at lower pressure levels than most rifles, their primer cups are thinner, softer, and easier to ignite, while rifle primers are thicker and stronger, requiring a harder impact from the [[firing pin]].<ref>Lyman ''Ideal Hand Book No. 36''. Lyman Gun Sight Corporation (1949) p. 45.</ref>  Despite the names ''pistol'' and ''rifle'', the primer used depends on the cartridge, not the firearm; a few high-pressure pistol cartridges like the [[.221 Fireball]] and [[.454 Casull]] use rifle primers, while lower-pressure pistol and revolver cartridges like the .32 ACP, .380 ACP, 9mm Parabellum, .38 Special, .357 Magnum, .44 Magnum, and .45 ACP, and traditional [[revolver]] cartridges like the .32-20, .44-40, and .45 Colt, also used in [[lever-action]] rifles, these cartridges would still be loaded with pistol primers. Virtually all cartridges used solely in rifles do, however, use rifle primers. Notable exceptions to this include [[.458 SOCOM]] and [[.50 Beowulf]], which use large pistol standard and large pistol magnum primers, respectively.