Im- PROVEMENTS IN THE MANUFACTURE OF CENTRAL-FIRE CARTRIDGES
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Clinton Edgcumbe Brooman
at the Office of the Commissioners of Patents, with his Petition,
on the 30th May 1868.-A communication from abroad by
Robert François Gosselin, of 23, Boulevard de Strasbourg, Paris,
France.
I, CLINTON EDGCUMBE BROOMAN, of the Firm of Robertson, Brooman,
and Company, of 166, Fleet Street, in the City of London, Patent
Agents, do hereby declare the nature of the said Invention for "Im-
PROVEMENTS IN THE MANUFACTURE OF CENTRAL-FIRE CARTRIDGES," to be as
follows:-
In central-fire percussion cartridges hitherto manufactured the
chamber at the base for containing the anvil and priming has had
the defect of giving way or becoming ruptured at the time of the
concussion, whereby numerous miss-fires occur, or there is escape of
the gases produced by the ignition of the powder.

page_text: The present Invention mainly consists in a metal chamber stamped
or formed with a shoulder with the view of strengthening the cartridge
by avoiding the displacement and giving way of the chamber; all the
parts of the cartridge or case are thus firmly united with the metallic
base or socket, whereby a strong cartridge free from gas escape is
produced.
The metal chamber is manufactured from a disc or blank as follows:-
The disc without re-heating is first stamped by hand so as to raise an
edge. The cup or shell thus formed is after a slight heating again
stamped so as to diminish its diameter and heighten the edge. After
being heated it is again stamped so as to diminish the diameter of the
lower half thereof. Another heating and stamping completes the
manufacture of the metal chamber; in this stamping the narrower
portion does not move, and the upper edge is turned over by a rebate in
the stamper to form a flange, the narrower end being pierced with
a hole.
Then to make a complete cartridge a short hollow cylinder of rolled
paper, pasteboard, or other plastic material is stamped into the form of a
plug of two different diameters; this is inserted into a metal base or
socket, the centre of the base being formed with an aperture and slightly
recessed to allow the metal chamber to be inserted. The chamber,
plug, and socket are then submitted to pressure in order to unite them
and to form the ordinary flange at the base. The paper tube to form
the body of the cartridge case, preferably lined at its lower end with
thin metal, is then inserted between the socket and the narrow portion
of the plug. The lower end of the tube is preferably turned in, and
it
may be strengthened with a ring of metal or other material, and the
remaining space between the socket and plug is filled up by a paper
ring. The whole is then submitted to pressure, whereby the upper
narrow portion of the plug is squashed and forced outwards, so as to
hold in the lower end of the tube and prevent all passage of the gases
between the plug and socket at the time of firing. The metal chamber
already secured behind the socket by its flange and held firmly in the
plug by its shoulder is then secured within the paper tube and above the
plug by a slight flattening given to its projecting narrow end. The
priming is now to be inserted. For this purpose a flat anvil is first
introduced into the chamber; the end of the anvil is then covered with

page_text: a cap, which in its turn is covered with a thimble; this thimble is
crushed or squashed at the time of the percussion. In case of rupture
or giving way of the cap the thimble hermetically closes the chamber of
the socket, and prevents escape of gas.