Primer Cups Caps

Priming compositions for centerfire ammunition are housed in small metal cups which fit into a recess, called the primer pocket, in the center of the base of the cartridge case. In rimfire ammunition the priming composition is housed inside the cartridge case in the hollow perimeter of the base. 

Two specifications for primer cup metal are (a) 95% to 98% copper and 5% to 2% zinc with not more than 0.05% lead, 0.1% arsenic, 0.002% bismuth, 0.01% antimony, and no more than a trace of any other impurity43 (b) 72% to 74% copper and 28% to 26% zinc with the total impurities not exceeding 0.1% and not more than 0.1% lead and 0.05% iron.44 

The Berdan cup is varnished internally when empty and after filling it is covered with a paper disc and then sealed with varnish. 

Cupronickel and copper alloy cups that are filled with a mercury fulminate-based primer composition are closed with a tinfoil disc that is varnished on the side that is in contact with the primer composition. A varnish that is frequently used for this purpose is shellac grade 1. After fitting, the cup annulus is coated with a clear varnish to prevent the ingress of moisture or oil. 

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. 

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

Cups, percussion or primer and caps 3 C577 Curds 3 C577... 

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... 

PersussioR Cap. (See under Cups, Percussion or Primer and Caps in Vol 3, C577 and Anvil of a Percussion Primer in Vol 1, A473-L)... 

The detonator (discriminating impact fuse) is a brass cup 3/16 V3/16 The wall thickness is about half that of a conventional primer. The Interior of the cap Is coated with a shock sensitive explosive, probably the same composition found in toy pistol caps (Pottasiym Chlorate, Red Phosphorus and Black Antimony Sulfide). The volume used is also about that of a toy cap. The cup is seated open end to the rear and is recessed about... 

Cups, Percussion or Primer and Cops. They are small metallic cups (or caps) contg primer compositions which are covered with ap er disc, and a metallic anvil" (See Vol 1, p A473-L). These cups are part of "explosive trains". On firing a weapon, the base of the cup is struck by the firing pin of the percussion lock. This action ign ites by impact the primer mixt in the ci ) producing a flash, which in turn ignites either the proplnt (if the cup is part of a primer used in a propellant train), or the primer mixt of a detonator or delay element (if the cup is part of a primer used in an artillery ammunition train)... 

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