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Centerfire ammunition

April 25, 2023

A centerfire cartridge is a firearm metallic cartridge whose primer is located at the center of the base of its casing (i.e. "case head"). Unlike rimfire cartridges, the centerfire primer is typically a separate component seated into a recessed cavity (known as the primer pocket) in the case head and is replaceable by reloading.

Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center

Centerfire cartridges have supplanted the rimfire variety in all but the smallest cartridge sizes. The majority of today's handguns, rifles, and shotguns use centerfire ammunition, with the exception of a few .17 caliber, .20 caliber, and .22 caliber handgun and rifle cartridges, small-bore shotgun shells (intended for pest control), and a handful of antique (and mostly obsolete) cartridges.

History

An early form of centerfire ammunition, without a percussion cap, was invented between 1808 and 1812 by Jean Samuel Pauly.[1] This was also the first fully integrated cartridge and used a form of obturation employing the cartridge itself. Another form of centerfire ammunition was invented by the Frenchman Clement Pottet in 1829;[2][3] however, Pottet would not perfect his design until 1855. 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.[4][3][5][6][7]

Advantages

 
Comparison of centerfire and rimfire ignition

Centerfire cartridges are more reliable for military purposes because the thicker metal cartridge cases can withstand rougher handling without damage, and safer to handle because explosive priming compound in a protruding rim is more likely to be triggered by impact if a rimfire cartridge is dropped or pinched. The stronger base of a centerfire cartridge is able to withstand higher pressures which in turn give a bullet 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. Larger caliber rimfire cartridges require greater volumes of priming explosive than centerfire cartridges, and the required volume may cause an undesirably high pressure during ignition. Reducing the amount of priming explosive would reduce the reliability of rimfire cartridge ignition, and increase the probability of misfire or dud cartridges.[8]

Economies of scale are achieved through interchangeable primers for a wide variety of centerfire cartridge calibers. The expensive individual brass cases can be reused after replacing the primer, gunpowder and projectile. 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. 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.

Primers

 
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.
 
Berdan (left) and Boxer (right) primed rifle cartridges.

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.[9] Berdan and Boxer cartridge primers are both considered "centerfire" and are not interchangeable at the primer level; however, the same weapon can fire either Berdan- or Boxer-primed cartridges if the overall dimensions are the same.[10]

The two primer types are almost impossible to distinguish by looking at the loaded cartridge, though the two (or more) flash-holes can be seen inside a fired Berdan case and the larger single hole seen or felt inside a fired Boxer case. Berdan priming is less expensive to manufacture and is much more common in military-surplus ammunition made outside the United States.

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 U.S. Patent 53,388. 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 (later to be known as an anvil) 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 U.S. Patent 82,587. 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 (rarely one or three) small holes by sides of the anvil that allow 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 or a pincer or lever that pulls the primer out of the bottom. A new primer is carefully seated against the anvil, and then powder and a bullet are added.

Centered single-hole primer

In 1880s-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[11] even though it was known from early-to-mid 1880s, where the anvil had a single fire hole right at its center.

Boxer primer

 
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.

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 U.S. 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 providing 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 round, but it makes fired primers vastly easier to remove for re-loading, 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 primers by the hundreds of millions has eliminated that as a practical problem. And while the primer is one step more complex to make, 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 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 mm) diameter primers for shotgun shells and modern inline muzzleloaders, using a Boxer-type primer factory-assembled inside a tapered, flanged brass cup
  • 0.210" (5.33 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.[12][13]
  • 0.315" (8.00 mm) diameter .50 BMG primers, used for the .50 Browning Machine Gun cartridge and derivatives

Examples of uses:

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 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.[14] 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 and .380 Autos, 9mm Luger, .38 Special, .357 Magnum, .44 Magnum and .45 ACP and traditional revolver cartridges like .32-20, .44-40 and .45 Colt, also used in lever-action rifles, still would be loaded with pistol primers. Virtually all cartridges used solely in rifles do, however, use rifle primers.

Shotgun primers

 
A fired pistol case as indicated by the dimple from a firing pin and a shotgun (right) primer against an inch and mm scale.

All modern shotgun shells (excluding specialized rimfire .22 "snake loads" or birdshot cartridges) are centerfire. They use a large, specific shotgun primer that is based on the Boxer system, in that the primer contains the anvil against which the primary explosive is compressed by the firing pin and deformation of the primer cup.

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.[15]

Cartridge primers

Primer actuated or piston primer cartridges use a primer in the form of a blank to contain the propellant within an empty cartridge, or in some cases as a piston to unlock the bolt and operate the weapon. These types of rounds are rarely used and are mostly found on spotting rifles.[16][17][18][19]

Primer chemistry

Primer manufacture and insertion is the most dangerous part of small arms ammunition production. Sensitive priming compounds have claimed many lives including the founder of the famous British Eley ammunition firm. Modern commercial operations use protective shielding between operators and manufacturing equipment.[20]

Early primers used the same mercury fulminate used in 19th century percussion caps. Black powder could be effectively ignited by hot mercury released upon decomposition. Disadvantages of mercuric primers became evident with smokeless powder loadings. Mercury fulminate slowly decomposed in storage until the remaining energy was insufficient for reliable ignition.[21] Decreased ignition energy with age had not been recognized as a problem with black-powder loadings because black powder could be ignited by as little energy as a static electricity discharge. Smokeless powder often required more thermal energy for ignition.[22] Misfires and hang fires became common as the remaining priming compound sputtered in old primers. 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. A hang fire is a perceptible delay between the fall of the firing pin and discharge of the firearm. 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.

Incandescent particles were found most effective for igniting smokeless powder after the primary explosive gases had heated the powder grains. Artillery charges frequently included a smaller quantity of black powder to be ignited by the primer, so incandescent potassium carbonate would spread fire through the smokeless powder.[23] Potassium chlorate was added to mercury fulminate priming mixtures so incandescent potassium chloride would have a similar effect in small arms cartridges.

Priming mixtures containing mercury fulminate leave metallic mercury in the bore and empty cartridge case after firing. The mercury was largely absorbed in the smokey fouling with black-powder loads. 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.[24] Frankford Arsenal FA-70 primers used potassium chlorate as an oxidizer for lead(II) thiocyanate, to increase the sensitivity of potassium chlorate, and antimony trisulfide, as an abrasive, with minor amounts of trinitrotoluene.[25] These corrosive primers leave a residue of potassium chloride salt in the bore after a cartridge is fired. These hygroscopic salt crystals will hold moisture from a humid atmosphere and cause rusting.[26] These corrosive primers can cause serious damage to the gun unless the barrel and action are cleaned carefully after firing.

Civilian ammunition manufacturers began offering non-corrosive primers in the 1920s, but most military ammunition continued to use corrosive priming mixtures of established reliability.[27] The various proprietary priming formulations used by different manufacturers produced some significantly different ignition properties[28] until the United States issued military specifications for non-corrosive primers for 7.62×51mm NATO cartridge production. 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.[25] Most United States manufacturers adopted the PA-101 military standard for their civilian production of Boxer primers.[29] 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.

Other explosives used in primers can include lead azide, potassium perchlorate, or diazodinitrophenol (DDNP). New on the market in the late 1990s are lead-free primers (see green bullet), to address concerns over the lead and other heavy-metal compounds found in older primers. The heavy metals, while small in quantity, are released in the form of a very fine soot. Some indoor firing ranges are moving to ban primers containing heavy metals due to their toxicity. Lead-free primers were originally less sensitive and had a greater moisture sensitivity and correspondingly shorter shelf life than normal noncorrosive primers.[citation needed] Since their introduction, lead-free primers have become better in their performance compared to early lead free primers.[30] Tests comparing lead-free primers to lead-based primers conducted by the US Department of Defense (approx 2006), exposed some significant differences in accuracy between the two primers when used in 7.62×51mm. In these tests, lead-free primers were proven to be not as accurate as lead-based primers. The lead-free primers exhibited poor performance as far as peak blast pressure, which consequently leads to poor ignition. Popularity is still minimal, as accuracy is paramount. Most lead-free primers are sourced through Russia (MUrom?)or South Korea (PMC).

European and eastern military or surplus ammunition often uses corrosive or slightly-corrosive Berdan primers because they work reliably under severe conditions and have a longer storage life than the non-corrosive type primers in current use. Modern Boxer primers are almost always non-corrosive and non-mercuric. Determination of corrosive or non-corrosive characteristics based on the primer type should consider these final headstamp dates of corrosive ammunition production:[31]

See also

References

  1. ^ "Small Arms Ammunition at the International Exposition Philadelphia, 1876" (PDF). DSpace Repository - Smithsonian Institution. (PDF) from the original on 2015-12-29. Retrieved 2015-10-19..
  2. ^ "Cartridges: Centerfire cartridge". firearmshistory.blogspot.co.uk. from the original on 20 October 2017. Retrieved 4 May 2018.
  3. ^ a b Westwood, David (2005). Rifles: An Illustrated History of Their Impact. ABC-CLIO. p. 29. ISBN 978-1-85109-401-1.
  4. ^ "The International Ammunition Association Journal, issue 504". 2015. p. 14.
  5. ^ Decisions of the Commissioner of Patents and of the United States Courts in Patent and Trade-mark and Copyright Cases. U.S. Government Printing Office. 1875. p. 83.
  6. ^ "Description des machines et procedes specifies dans les brevets d'invention, de perfectionnement et d'importation, dont la duree est expirée". 1847.
  7. ^ Deane, John (1858). "Deanes' Manual of the History and Science of Fire-arms".
  8. ^ Treadwell, T.J. (1873). Metallic Cartridges, (Regulation and Experimental,) as Manufactured and Tested at the Frankford Arsenal, Philadelphia, PA. Washington, DC: United States Government Printing Office. p. 9.
  9. ^ Davis, William C., Jr. Handloading (1981) National Rifle Association of America p.65
  10. ^ Sporting Arms and Ammunition Manufacturers' Institute
  11. ^ AT 15483B , diagram at [1]
  12. ^ "FAQ". from the original on 27 March 2014. Retrieved 27 March 2014.
  13. ^ Calhoon, James (October 1995). "Primers and Pressure". Varmint Hunter. from the original on 2015-01-07.
  14. ^ Lyman Ideal Hand Book No. 36. Lyman Gun Sight Corporation (1949) p. 45.
  15. ^ "Turkish Small-Bore Shotshells Called 6mm Pipet -". 25 September 2018.
  16. ^ "Cartridge of the Month".
  17. ^ "Cartridge of the Month".
  18. ^ "7mm_compromise".
  19. ^ http://www.cartrology.com/cartridges/627[bare URL]
  20. ^ Sharpe, Philip B. Complete Guide To Handloading (1953) Funk & Wagnalls p. 51
  21. ^ "PowerLabs Fulminate Explosives Synthesis". PowerLabs. from the original on 2012-04-12. Retrieved 2012-06-07.
  22. ^ Lyman Ideal Hand Book No. 36 Lyman Gun Sight Corporation (1949) p. 49
  23. ^ Fairfield, A.P., CDR, USN Naval Ordnance (1921) Lord Baltimore Press pp. 48–49
  24. ^ Davis, William C., Jr. Handloading (1981) National Rifle Association of America p .20
  25. ^ a b Lake, E.R. & Drexelius, V.W. Percussion Primer Design Requirements (1976) McDonnell-Douglas
  26. ^ Sharpe, Philip B. Complete Guide To Handloading (1953) Funk & Wagnalls p. 60
  27. ^ Davis, William C., Jr. Handloading (1981) National Rifle Association of America p. 21
  28. ^ Landis, Charles S. (1947). Twenty-Two Caliber Varmint Rifles. Harrisburg, Pennsylvania: Small-Arms Technical Publishing Company. p. 440.
  29. ^ Sharpe, Philip B. Complete Guide To Handloading (1953) Funk & Wagnalls p. 239
  30. ^ as reported by AccurateShooter.com in October 2011
  31. ^ Davis, William C., Jr. Handloading (1981) National Rifle Association of America pp. 21–22
  32. ^ Davis, William C., Jr. Handloading (1981) National Rifle Association of America p. 12

Further reading

  • Corrosive Primer Redux by M.E. Podany, ALGC. Includes more detailed information on identifying USGI corrosive and non-corrosive ammunition based on cartridge headstamp. This article refers to The American Rifleman, "Beginners Digest: Nonmercuric, Noncorrosive Primers", pp. 34–36, January 1961.

April 25, 2023
centerfire, ammunition, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, needs, additional, citations, verification, please, help, improve, this, article,. This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Centerfire ammunition news newspapers books scholar JSTOR February 2011 Learn how and when to remove this template message This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations February 2011 Learn how and when to remove this template message Learn how and when to remove this template message A centerfire cartridge is a firearm metallic cartridge whose primer is located at the center of the base of its casing i e case head Unlike rimfire cartridges the centerfire primer is typically a separate component seated into a recessed cavity known as the primer pocket in the case head and is replaceable by reloading Two rounds of 357 Magnum a centerfire cartridge notice the circular primer in the center Centerfire cartridges have supplanted the rimfire variety in all but the smallest cartridge sizes The majority of today s handguns rifles and shotguns use centerfire ammunition with the exception of a few 17 caliber 20 caliber and 22 caliber handgun and rifle cartridges small bore shotgun shells intended for pest control and a handful of antique and mostly obsolete cartridges Contents 1 History 2 Advantages 3 Primers 3 1 Berdan primer 3 1 1 Centered single hole primer 3 2 Boxer primer 3 3 Shotgun primers 3 4 Cartridge primers 4 Primer chemistry 5 See also 6 References 7 Further readingHistory EditAn early form of centerfire ammunition without a percussion cap was invented between 1808 and 1812 by Jean Samuel Pauly 1 This was also the first fully integrated cartridge and used a form of obturation employing the cartridge itself Another form of centerfire ammunition was invented by the Frenchman Clement Pottet in 1829 2 3 however Pottet would not perfect his design until 1855 The centerfire cartridge was improved by Beatus Beringer Benjamin Houllier Gastinne Renette Smith amp Wesson Charles Lancaster Jules Felix Gevelot George Morse Francois Schneider Hiram Berdan and Edward Mounier Boxer 4 3 5 6 7 Advantages Edit Comparison of centerfire and rimfire ignition Centerfire cartridges are more reliable for military purposes because the thicker metal cartridge cases can withstand rougher handling without damage and safer to handle because explosive priming compound in a protruding rim is more likely to be triggered by impact if a rimfire cartridge is dropped or pinched The stronger base of a centerfire cartridge is able to withstand higher pressures which in turn give a bullet 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 Larger caliber rimfire cartridges require greater volumes of priming explosive than centerfire cartridges and the required volume may cause an undesirably high pressure during ignition Reducing the amount of priming explosive would reduce the reliability of rimfire cartridge ignition and increase the probability of misfire or dud cartridges 8 Economies of scale are achieved through interchangeable primers for a wide variety of centerfire cartridge calibers The expensive individual brass cases can be reused after replacing the primer gunpowder and projectile Handloading reuse is an advantage for rifles using obsolete or hard to find centerfire cartridges such as the 6 5 54mm Mannlicher Schonauer 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 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 Primers Edit 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 Berdan left and Boxer right primed rifle cartridges 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 9 Berdan and Boxer cartridge primers are both considered centerfire and are not interchangeable at the primer level however the same weapon can fire either Berdan or Boxer primed cartridges if the overall dimensions are the same 10 The two primer types are almost impossible to distinguish by looking at the loaded cartridge though the two or more flash holes can be seen inside a fired Berdan case and the larger single hole seen or felt inside a fired Boxer case Berdan priming is less expensive to manufacture and is much more common in military surplus ammunition made outside the United States Berdan primer Edit 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 Patent 53 388 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 later to be known as an anvil 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 U S Patent 82 587 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 rarely one or three small holes by sides of the anvil that allow 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 or a pincer or lever that pulls the primer out of the bottom A new primer is carefully seated against the anvil and then powder and a bullet are added Centered single hole primer Edit In 1880s 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 11 even though it was known from early to mid 1880s where the anvil had a single fire hole right at its center Boxer primer Edit 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 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 U S 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 providing 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 round but it makes fired primers vastly easier to remove for re loading 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 primers by the hundreds of millions has eliminated that as a practical problem And while the primer is one step more complex to make 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 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 mm diameter primers for shotgun shells and modern inline muzzleloaders using a Boxer type primer factory assembled inside a tapered flanged brass cup 0 210 5 33 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 12 13 0 315 8 00 mm diameter 50 BMG primers used for the 50 Browning Machine Gun cartridge and derivativesExamples of uses 38 Special small pistol standard 357 Magnum small pistol magnum 45 ACP large pistol standard small pistol standard less frequent 44 Magnum large pistol magnum 223 Remington small rifle standard 308 Winchester large rifle standard 270 WSM large rifle magnumPrimer 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 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 14 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 and 380 Autos 9mm Luger 38 Special 357 Magnum 44 Magnum and 45 ACP and traditional revolver cartridges like 32 20 44 40 and 45 Colt also used in lever action rifles still would be loaded with pistol primers Virtually all cartridges used solely in rifles do however use rifle primers Shotgun primers Edit A fired pistol case as indicated by the dimple from a firing pin and a shotgun right primer against an inch and mm scale All modern shotgun shells excluding specialized rimfire 22 snake loads or birdshot cartridges are centerfire They use a large specific shotgun primer that is based on the Boxer system in that the primer contains the anvil against which the primary explosive is compressed by the firing pin and deformation of the primer cup 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 15 Cartridge primers Edit Primer actuated or piston primer cartridges use a primer in the form of a blank to contain the propellant within an empty cartridge or in some cases as a piston to unlock the bolt and operate the weapon These types of rounds are rarely used and are mostly found on spotting rifles 16 17 18 19 Primer chemistry EditPrimer manufacture and insertion is the most dangerous part of small arms ammunition production Sensitive priming compounds have claimed many lives including the founder of the famous British Eley ammunition firm Modern commercial operations use protective shielding between operators and manufacturing equipment 20 Early primers used the same mercury fulminate used in 19th century percussion caps Black powder could be effectively ignited by hot mercury released upon decomposition Disadvantages of mercuric primers became evident with smokeless powder loadings Mercury fulminate slowly decomposed in storage until the remaining energy was insufficient for reliable ignition 21 Decreased ignition energy with age had not been recognized as a problem with black powder loadings because black powder could be ignited by as little energy as a static electricity discharge Smokeless powder often required more thermal energy for ignition 22 Misfires and hang fires became common as the remaining priming compound sputtered in old primers 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 A hang fire is a perceptible delay between the fall of the firing pin and discharge of the firearm 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 Incandescent particles were found most effective for igniting smokeless powder after the primary explosive gases had heated the powder grains Artillery charges frequently included a smaller quantity of black powder to be ignited by the primer so incandescent potassium carbonate would spread fire through the smokeless powder 23 Potassium chlorate was added to mercury fulminate priming mixtures so incandescent potassium chloride would have a similar effect in small arms cartridges Priming mixtures containing mercury fulminate leave metallic mercury in the bore and empty cartridge case after firing The mercury was largely absorbed in the smokey fouling with black powder loads 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 24 Frankford Arsenal FA 70 primers used potassium chlorate as an oxidizer for lead II thiocyanate to increase the sensitivity of potassium chlorate and antimony trisulfide as an abrasive with minor amounts of trinitrotoluene 25 These corrosive primers leave a residue of potassium chloride salt in the bore after a cartridge is fired These hygroscopic salt crystals will hold moisture from a humid atmosphere and cause rusting 26 These corrosive primers can cause serious damage to the gun unless the barrel and action are cleaned carefully after firing Civilian ammunition manufacturers began offering non corrosive primers in the 1920s but most military ammunition continued to use corrosive priming mixtures of established reliability 27 The various proprietary priming formulations used by different manufacturers produced some significantly different ignition properties 28 until the United States issued military specifications for non corrosive primers for 7 62 51mm NATO cartridge production 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 25 Most United States manufacturers adopted the PA 101 military standard for their civilian production of Boxer primers 29 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 Other explosives used in primers can include lead azide potassium perchlorate or diazodinitrophenol DDNP New on the market in the late 1990s are lead free primers see green bullet to address concerns over the lead and other heavy metal compounds found in older primers The heavy metals while small in quantity are released in the form of a very fine soot Some indoor firing ranges are moving to ban primers containing heavy metals due to their toxicity Lead free primers were originally less sensitive and had a greater moisture sensitivity and correspondingly shorter shelf life than normal noncorrosive primers citation needed Since their introduction lead free primers have become better in their performance compared to early lead free primers 30 Tests comparing lead free primers to lead based primers conducted by the US Department of Defense approx 2006 exposed some significant differences in accuracy between the two primers when used in 7 62 51mm In these tests lead free primers were proven to be not as accurate as lead based primers The lead free primers exhibited poor performance as far as peak blast pressure which consequently leads to poor ignition Popularity is still minimal as accuracy is paramount Most lead free primers are sourced through Russia MUrom or South Korea PMC European and eastern military or surplus ammunition often uses corrosive or slightly corrosive Berdan primers because they work reliably under severe conditions and have a longer storage life than the non corrosive type primers in current use Modern Boxer primers are almost always non corrosive and non mercuric Determination of corrosive or non corrosive characteristics based on the primer type should consider these final headstamp dates of corrosive ammunition production 31 45 ACP FA 54 FCC 53 RA 52 TW 53 WCC 52 WRA 54 30 06 Springfield FA 56 LC 52 RA 51 SL 52 TW 52 WCC 51 WRA 54 FN 57 32 See also EditHeeled bulletReferences Edit Small Arms Ammunition at the International Exposition Philadelphia 1876 PDF DSpace Repository Smithsonian Institution Archived PDF from the original on 2015 12 29 Retrieved 2015 10 19 Cartridges Centerfire cartridge firearmshistory blogspot co uk Archived from the original on 20 October 2017 Retrieved 4 May 2018 a b Westwood David 2005 Rifles An Illustrated History of Their Impact ABC CLIO p 29 ISBN 978 1 85109 401 1 The International Ammunition Association Journal issue 504 2015 p 14 Decisions of the Commissioner of Patents and of the United States Courts in Patent and Trade mark and Copyright Cases U S Government Printing Office 1875 p 83 Description des machines et procedes specifies dans les brevets d invention de perfectionnement et d importation dont la duree est expiree 1847 Deane John 1858 Deanes Manual of the History and Science of Fire arms Treadwell T J 1873 Metallic Cartridges Regulation and Experimental as Manufactured and Tested at the Frankford Arsenal Philadelphia PA Washington DC United States Government Printing Office p 9 Davis William C Jr Handloading 1981 National Rifle Association of America p 65 Sporting Arms and Ammunition Manufacturers Institute AT 15483B diagram at 1 FAQ Archived from the original on 27 March 2014 Retrieved 27 March 2014 Calhoon James October 1995 Primers and Pressure Varmint Hunter Archived from the original on 2015 01 07 Lyman Ideal Hand Book No 36 Lyman Gun Sight Corporation 1949 p 45 Turkish Small Bore Shotshells Called 6mm Pipet 25 September 2018 Cartridge of the Month Cartridge of the Month 7mm compromise http www cartrology com cartridges 627 bare URL Sharpe Philip B Complete Guide To Handloading 1953 Funk amp Wagnalls p 51 PowerLabs Fulminate Explosives Synthesis PowerLabs Archived from the original on 2012 04 12 Retrieved 2012 06 07 Lyman Ideal Hand Book No 36 Lyman Gun Sight Corporation 1949 p 49 Fairfield A P CDR USN Naval Ordnance 1921 Lord Baltimore Press pp 48 49 Davis William C Jr Handloading 1981 National Rifle Association of America p 20 a b Lake E R amp Drexelius V W Percussion Primer Design Requirements 1976 McDonnell Douglas Sharpe Philip B Complete Guide To Handloading 1953 Funk amp Wagnalls p 60 Davis William C Jr Handloading 1981 National Rifle Association of America p 21 Landis Charles S 1947 Twenty Two Caliber Varmint Rifles Harrisburg Pennsylvania Small Arms Technical Publishing Company p 440 Sharpe Philip B Complete Guide To Handloading 1953 Funk amp Wagnalls p 239 as reported by AccurateShooter com in October 2011 Davis William C Jr Handloading 1981 National Rifle Association of America pp 21 22 Davis William C Jr Handloading 1981 National Rifle Association of America p 12Further reading EditCorrosive Primer Redux by M E Podany ALGC Includes more detailed information on identifying USGI corrosive and non corrosive ammunition based on cartridge headstamp This article refers to The American Rifleman Beginners Digest Nonmercuric Noncorrosive Primers pp 34 36 January 1961 Retrieved from https en wikipedia org w index php title Centerfire ammunition amp oldid 1151572330, wikipedia, wiki, book, books, library,

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