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Two rounds of .357 Magnum, a centerfire cartridge; notice the circular primer in the center A centerfire cartridge is a
firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...
metallic cartridge whose
primer Primer may refer to: Arts, entertainment, and media Films * ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth * ''Primer'' (video), a documentary about the funk band Living Colour Literature * Primer (textbook), a te ...
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. Centerfire cartridges have supplanted the rimfire variety in all but the smallest cartridge sizes. The majority of today's handguns,
rifle A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...
s, and
shotgun A shotgun (also known as a scattergun, or historically as a fowling piece) is a long-barreled firearm designed to shoot a straight-walled cartridge known as a shotshell, which usually discharges numerous small pellet-like spherical sub- pr ...
s use centerfire ammunition, with the exception of a few .17 caliber, .20 caliber, and
.22 caliber .22 caliber, or 5.6 mm caliber, refers to a common firearms bore diameter of 0.22 inch (5.6 mm). Cartridges in this caliber include the very widely used .22 Long Rifle and .223 Remington / 5.56×45mm NATO. .22 inch is also a popular ...
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. This was also the first fully integrated cartridge and used a form of
obturation In the field of firearms and airguns, obturation denotes necessary barrel blockage or fit by a deformed soft projectile (obturation in general is closing up an opening). A bullet or pellet, made of soft material and often with a concave base, wi ...
employing the cartridge itself. Another form of centerfire ammunition was invented by the Frenchman Clement Pottet in 1829; 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.


Advantages

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.
Economies of scale In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of output produced per unit of time. A decrease in cost per unit of output enables ...
are achieved through interchangeable primers for a wide variety of centerfire cartridge calibers. The expensive individual
brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...
cases can be reused after replacing the primer, gunpowder and projectile.
Handloading Handloading, or reloading, is the practice of making firearm cartridges by assembling the individual components (case, primer, propellant, and projectile), rather than purchasing mass-assembled, factory-loaded ammunition. The term ''handlo ...
reuse is an advantage for rifles using obsolete or hard-to-find centerfire cartridges such as the
6.5×54mm Mannlicher–Schönauer The 6.5×54mm Mannlicher–Schönauer also known as 6.5×54 Mannlicher–Schönauer Greek or simply 6.5 Greek is a 6.5 mm (.264" cal.) rimless rifle cartridge used in the Mannlicher–Schönauer rifle. It is the direct descendant of the 6.5� ...
, or larger calibers such as the
.458 Lott The .458 Lott is a .458 caliber rifle cartridge designed for the purpose of hunting large, thick-skinned dangerous game animals in Africa. It is based on the full length .375 H&H Magnum case blown out and shortened to . The .458 Lott was des ...
, 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 identifying feature of centerfire ammunition is the
primer Primer may refer to: Arts, entertainment, and media Films * ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth * ''Primer'' (video), a documentary about the funk band Living Colour Literature * Primer (textbook), a te ...
which is a metal cup containing a
primary explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ...
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 Incandescence is the emission of electromagnetic radiation (including visible light) from a hot body as a result of its high temperature. The term derives from the Latin verb ''incandescere,'' to glow white. A common use of incandescence i ...
particles to ignite the powder charge. Davis, William C., Jr. ''Handloading'' (1981) National Rifle Association of America p.65 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.
Sporting Arms and Ammunition Manufacturers' Institute The Sporting Arms and Ammunition Manufacturers' Institute (SAAMI, pronounced "Sammy") is an association of American manufacturers of firearms, ammunition, and components. SAAMI is an accredited standards developer that publishes several Amer ...
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 . 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 . 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 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 . 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 In microeconomics, economies of scale are the cost advantages that enterprises obtain due to their scale of operation, and are typically measured by the amount of output produced per unit of time. A decrease in cost per unit of output enables ...
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. * 0.315" (8.00 mm) diameter .50 BMG primers, used for the .50 Browning Machine Gun cartridge and derivatives Examples of uses: *
.38 Special The .38 Special, also commonly known as .38 S&W Special (not to be confused with .38 S&W), .38 Smith & Wesson Special, .38 Spl, .38 Spc, (pronounced "thirty-eight special"), or 9x29mmR is a rimmed, centerfire cartridge designed by Smith & ...
, small pistol standard *
.357 Magnum The .357 Smith & Wesson Magnum, .357 S&W Magnum, .357 Magnum, or 9×33mmR as it is known in unofficial metric designation, is a smokeless powder cartridge with a bullet diameter. It was created by Elmer Keith, Phillip B. Sharpe, and Douglas B. ...
, small pistol magnum *
.45 ACP The .45 ACP ( Automatic Colt Pistol) or .45 Auto (11.43×23mm) is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it ...
, large pistol standard, small pistol standard (less frequent) * .44 Magnum, large pistol magnum *
.223 Remington The .223 Remington (designated as the 223 Remington by the SAAMI and 223 Rem by the CIP) is a rimless, bottlenecked rifle cartridge. It was developed in 1957 by Remington Arms and Fairchild Industries for the U.S. Continental Army Command ...
, small rifle standard *
.308 Winchester The .308 Winchester is a smokeless powder rimless bottlenecked rifle cartridge widely used for hunting, target shooting, police, military, and personal protection applications globally. It is similar but not identical to the 7.62×51mm NATO ...
, large rifle standard *
.270 WSM The 270 Winchester Short Magnum or 270 WSM is a short, unbelted, magnum cartridge created by necking down the .300 Winchester Short Magnum and fitting it with a .277 caliber bullet. The correct name for the cartridge, as listed by the Sporting A ...
, 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 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. 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 The .221 Remington Fireball, often simply referred to as .221 Fireball, is a centerfire cartridge created by Remington Arms Company in 1963 as a special round for use in their experimental single-shot bolt-action pistol, the XP-100. A shortene ...
and
.454 Casull The .454 Casull () is a firearm cartridge, developed as a wildcat cartridge in 1958 by Dick Casull, Duane Marsh and Jack Fullmer. It was announced in November 1959 by ''Guns & Ammo'' magazine. The design is a lengthened and structurally improve ...
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 A revolver (also called a wheel gun) is a repeating firearm, repeating handgun that has at least one gun barrel, barrel and uses a revolving cylinder (firearms), cylinder containing multiple chamber (firearms), chambers (each holding a single ...
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

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.


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.


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.Sharpe, Philip B. ''Complete Guide To Handloading'' (1953) Funk & Wagnalls p. 51 Early primers used the same mercury fulminate used in 19th century percussion caps.
Black powder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). T ...
could be effectively ignited by hot mercury released upon decomposition. Disadvantages of mercuric primers became evident with
smokeless powder Finnish smokeless powderSmokeless powder is a type of propellant used in firearms and artillery that produces less smoke and less fouling when fired compared to gunpowder ("black powder"). The combustion products are mainly gaseous, compared t ...
loadings. Mercury fulminate slowly decomposed in storage until the remaining energy was insufficient for reliable ignition. 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. 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.
Potassium chlorate Potassium chlorate is a compound containing potassium, chlorine and oxygen, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. After sodium chlorate, it is the second most common chlorate in industrial use. ...
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 Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other wi ...
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 Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
and
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
amalgams weakening the case so it became unsuitable for reloading. The
United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, ...
discontinued use of mercuric priming mixtures in 1898 to allow arsenal reloading of fired cases during peacetime. Davis, William C., Jr. ''Handloading'' (1981) National Rifle Association of America p .20
Frankford Arsenal The Frankford Arsenal is a former United States Army ammunition plant located adjacent to the Bridesburg neighborhood of Northeast Philadelphia, Pennsylvania, north of the original course of Frankford Creek. History Opened in 1816 on of land ...
FA-70 primers used potassium chlorate as an oxidizer for
lead(II) thiocyanate Lead(II) thiocyanate is a compound, more precisely a salt, with the formula Pb(SCN)2. It is a white crystalline solid, but will turn yellow upon exposure to light. It is slightly soluble in water and can be converted to a basic salt (Pb(CNS)2·Pb( ...
, to increase the sensitivity of potassium chlorate, and antimony trisulfide, as an abrasive, with minor amounts of
trinitrotoluene Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reage ...
.Lake, E.R. & Drexelius, V.W. ''Percussion Primer Design Requirements'' (1976) McDonnell-Douglas These corrosive primers leave a residue of potassium chloride salt in the bore after a cartridge is fired. These
hygroscopic Hygroscopy is the phenomenon of attracting and holding water molecules via either absorption or adsorption from the surrounding environment, which is usually at normal or room temperature. If water molecules become suspended among the substance' ...
salt crystals will hold moisture from a humid atmosphere and cause rusting.Sharpe, Philip B. ''Complete Guide To Handloading'' (1953) Funk & Wagnalls p. 60 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. Davis, William C., Jr. ''Handloading'' (1981) National Rifle Association of America p. 21 The various proprietary priming formulations used by different manufacturers produced some significantly different ignition properties until the United States issued military specifications for non-corrosive primers for
7.62×51mm NATO The 7.62×51mm NATO (official NATO nomenclature 7.62 NATO) is a rimless, bottlenecked rifle cartridge. It is a standard for small arms among NATO countries. First developed in the 1950s, the cartridge had first been introduced in U.S. service fo ...
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 Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...
and a tetrazine compound. Most United States manufacturers adopted the PA-101 military standard for their civilian production of Boxer primers.Sharpe, Philip B. ''Complete Guide To Handloading'' (1953) Funk & Wagnalls p. 239 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 Lead(II) azide is an inorganic compound. More so than other azides, is explosive. It is used in detonators to initiate secondary explosives. In a commercially usable form, it is a white to buff powder. Preparation and handling Lead(II) azide i ...
, 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. Since their introduction, lead-free primers have become better in their performance compared to early lead free primers.as reported by AccurateShooter.com in October 2011 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 A headstamp is the markings on the bottom of a cartridge case designed for a firearm. It usually tells who manufactured the case. If it is a civilian case it often also tells the caliber: if it is military, the year of manufacture is often adde ...
dates of corrosive ammunition production: Davis, William C., Jr. ''Handloading'' (1981) National Rifle Association of America pp. 21–22 *
.45 ACP The .45 ACP ( Automatic Colt Pistol) or .45 Auto (11.43×23mm) is a rimless straight-walled handgun cartridge designed by John Moses Browning in 1904, for use in his prototype Colt semi-automatic pistol. After successful military trials, it ...
: FA 54, FCC 53, RA 52, TW 53, WCC 52, WRA 54 *
.30-06 Springfield The .30-06 Springfield cartridge (pronounced "thirty- aught-six" ), 7.62×63mm in metric notation, and called the .30 Gov't '06 by Winchester, was introduced to the United States Army in 1906 and later standardized; it remained in military use ...
: FA 56, LC 52, RA 51, SL 52, TW 52, WCC 51, WRA 54 * FN 57 Davis, William C., Jr. ''Handloading'' (1981) National Rifle Association of America p. 12


See also

* Heeled bullet


References


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. {{Handloading Ammunition