Primer cups

Original Special Primers supplied by Frankford Arsenal Correction made for oxygen in primer cup, anvil, and paper... 

Sensitivity testing of primers (Refs 3 IS) is conducted with the primers inserted into the specified cartridge case in which they are to be used. The primer is inserted into the primer pocket of the cartridge case so that.the surface of the primer cup, when measured from the center of the primer, is within the tolerance specified on the applicable cartridge drawing. The test is performed in accordance with the complete run-down method described in TECP 700-700, Volume III. AMCR 717-505, Volumes 3 and 5 or AMSMU-P-715-501 FA1, as applicable... 

In mechanical fuses, where percussion primers are required, it seems fairly obvious that space requirements impose limits on the size of spring mechanisms or other physical modes of causing firing pins to move. The result is that, for fuses and other applications of this type, it becomes necessary to use primers of greatly increased sensitivity (Refs 6 8). This condition is illustrated with the M29A1 primer which is required to fire with an applied energy of 16 inch-ounces. This increased sensitivity is achieved by the use of thinner primer cup metal of softer alloy. Sensitivity can be further enhanced by the use of more sensitive priming mixt (Refs 2,6 20)... 

Primer Cap or Primer Cup A small metallic container, into which the primer mixture is loaded (Ref 40a, p 112)... 

Friction Igniter consists of a primer cup contg a mixt of K chlorate, charcoal and dextrin binder. A loop of wire coated with red phosphorus in shellac extends thru this cup... 

Pb sulfocyanate 25.0 PETN 10.0% (Moisten a 6 lb batch with 350 ml of the same mixt as listed in Fig 3-8 for Primer FA70. Solvent is evaporated after wet loading primer cups)... 

The primer cup, or body, is constructed of a metal having a specified thickness and hardness such that when the bottom, or dome, of the primer is struck with a nonsharp firing pin, the primer will be initiated without rupture or blow-back at the point of detonation. 

The components of Navy percussion fuze primers contg MF usually consist of a Cu (or cartridge brass) primer cup, a tin (or Cu) sealing cup or disk, and a tin-plated brass anvil. Cartridge brass and gilding-metal is used by the Army for primer cups contg MF... 

Fuze, Per cussion. A fuze actuated by a sharp blow of a firing pin with a dull end on a primer, without breaking thru wall of primer cup (See Section 3 of this work)... 

The Paris gunmakers, Pr61at Deboubert, patented in 1820 primer cups filled with Ag or Hg fulminates. However, the first practical use of such cups is attributed to E. Wright (ca 1823) and F. Joyce (1824). Percussion primer caps were a great improvement over the old flintlocks. The first priming compns contd MF mixed with chlorates abrasives, some of which are still used today, although more modern formulations, such as those contg LSt, are available in many countries Refs l)Marshall 1 (1917), 37 2 (1917), 516 -20 2)Colver (1918), 513 3)Marshall 3 (1932), 160 4)Hayes (1038), 574 5)Ohart (19461, 51 6)TM 9-1910 (1955), 113-18 209... 

The primer cup contains a mixture of chemicals which sensitize each other to percussion and rapid burning, and consequently the primer burns rapidly producing a flame and a shower of hot particles that penetrates and ignites the propellant. 

The joint between the primer cup and the outside of the cartridge case base is sealed with lacquer to prevent the ingress of moisture and oil. The lacquer is sometimes color coded as an aid to visual inspection during manufacture, and also sometimes to identify the type of bullet, for example, ball, tracer, armor piercing. Sometimes the mouth of the case is internally varnished, just before inserting the bullet, to waterproof the joint and to provide... 

Generally speaking primer cups for rifles differ in size, structure, and amount of priming composition from those used for pistols and revolvers. Primer cups for use in rifles, pistols, and revolvers range in size from 0.175 to 0.210 inches in diameter. For shotgun cartridges, the primer cup is typically in the range 0.240 to 0.245 inches in diameter. 

Although this was a simple, relatively safe mixture, and was a satisfactory primer, it was discontinued after a very short period because of two major disadvantages. It was shown that copper, bismuth, silver, iron, and nickel increased the oxidation rate of red phosphorus to acidic compounds. Primer cups had to be zinc plated to prevent contact with copper. The red phosphorus had to be of high purity, and it was necessary to remove the major impurities (iron and copper) from commercial red phosphorus before use, and to coat the purified material with up to 7.5% aluminum hydroxide which inhibited oxidation. 

Only one of the two nickel-jacketed bullets, number 43, gave nickel on the perimeter of the bullet hole. Nickel was frequently detected from nonnickel-coated bullets. This is a surprising result which demonstrates that the presence of nickel cannot be used to identify the use of a nickel-jacketed bullet. The origin of the nickel is unknown but it may have originated from the primer cup coating. 

Burned K and S at major level Cartridge case and primer cup Cu with a trace of Zn Discharge primer residue (elements listed in descending order) ... 

There is no lead or barium in the primer yet discharge particles from this ammunition frequently contain lead, antimony, and barium. The lead and barium must come from other components in the ammunition (bullet core/propellant) and/or from contamination in the firearm. Tin was also frequently present in the discharge particles and originates from the tinfoil disc used to seal the primer cup in mercury fulminate primers. 

Brass is the most popular material for cartridge cases and primer cups, with steel the second most widely used material for cartridge case manufacture. Soft copper primer cups encountered were all from old ammunition containing black powder propellant. 

AUTO, REM-UMC, round Cu jacket/Pb core, brass case, Ni-coated brass primer cup... 

AUTO, R-P, round. 32 AUTO, GECO LT, round. 32 AUTO, RWS, round Cu jacket/Pb core, double-based propellant Ni-coated brass jacket/Pb core, brass case Unjacketed Pb bullet, brass case, Cu primer cup, black powder... 

UMC, round Lubricated unjacketed Pb bullet, brass case, Cu primer cup, black powder... 

Mk, HP, round Fe jacket/Pb core (trace Sb, Fe, Cu, Al, Si), Al-coated steel case, Ni-coated brass primer cup propellant contains K and S Pb, Sb, Ba primer... 

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