Improvements in central fire cartridges for Military or Sporting Guns or other fire-arms
Year: 1887

page_text: Date of Application, 26th Mar., 1887.
Specification Accepted, 26th Apr., 1887.
[Communicated from abroad by LA SOCIÉTÉ FRANÇAISE DES MUNITIONS DE CHASSE
DE TIR ET DE GUERRE, of 30, Rue Notre Dame des Victoires, Paris, in the
Republic of France.]
I, JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This Invention of Improvements in central fire cartridges for Military or Sporting
Guns or other fire-arms relates to new arrangements and combinations of parts for the
reception of the fulminate or priming as hereinafter explained.
The nature of the pyroxilin powders and the large charges of ordinary or black
Gunpowder, which are now becoming more and more general, exert excessive
pressure in the cartridges and produce the following consequences, videlicet:-
(1.) Escape of gas around the cap, (2.) A forcing back of the bottom of the cap into
the hole for the striker.
The disadvantages of the escape of Gas are as follows:
These leakages which in guns with external hammers, inconvenience and sometimes
even injure the person firing the gun, cause troubles of another kind in the case of
hammerless guns. In these guns, all the mechanism of the cock is in communication
with the hole in which the striker works. Any leakage, however small, soon renders
the parts foul, so that the mechanism becomes inoperative until cleaned by a skilful
hand. The evil resulting from the bulging out of the cap is that in guns in which
the striker flies back quickly after striking, the bottom of the cap being unsupported
is bulged or forced out into the hole in which the striker works.
The portion thus projecting in the case of military guns with sliding breech block
and in the case of break-down Sporting Guns, prevents, or at least renders difficult,
the opening of the breech. In Guns, with rotating action, such as revolvers, this
bulging out completely stops the rotation of the breech-piece,
A •

page_text: The attempts which have heretofore been made to obviate these two disadvantages
are numerous, but in no system heretofore introduced, have the three conditions,
essential to a good cartridge, been combined. These three conditions are the following,
vizt. (1) Facility for repriming or renewing the cap. (2.) Immunity from leakage
or escape of Gas through the cap. (3.) The bottom of the cap must not be liable to
become bulged outwards. These three conditions are fulfilled by means of this Inven-
tion by the employment of a priming apparatus, consisting of a removable chamber,
entirely closed, with the exception of a small vent or pin-hole on the side within the
cartridge, the said chamber containing a concealed cap, carrying the fulminate, and
being so arranged, that owing to the thickness of the end, it cannot be forced or
bulged out towards the striker under the pressure of the gas, thus providing absolute
immunity from leakage.
And in order that the said Invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to all the
figures on annexed Sheet of drawings the same letters of reference indicating
corresponding parts in all the figures.
Figure 1 of the accompanying drawings illustrates in section a priming chamber
arranged according to this Invention the several parts being also shewn detached in
the same figure. This priming chamber is composed of four parts namely (1) a cup A
perforated with a vent hole ai a and having its edge bent outwards so as to form
a rim or flange b (2) An anvil B cut out of a piece of sheet metal (3) A priming
cap C of thin copper containing the fulminate ate the said fulminate being protected
by a wad or disc d of paper or thin metal (4) A base D siamped out of relatively
thick metal. The edge of this Case being bent over so as to embrace the rim of the
cup A forms a joint which prevents any escape of gas and its thickness is such as to
render it incapable of being bulged out into the hole of the striker.
Figure 2 similarly illustrates a modified form of the same principle of construction.
This priming chamber is composed of (1) a cup E made of relatively thick metal on
which a rime is formed either by expanding or contracting the metal. It is preferable
to make it by contracting the metal as this process produces a stronger rim. If
desired the cup may be made with a solid rim or flange as indicated at E. The
chamber is also provided with (2) an anvil B and with (3) a cap C for the priming
as in the arrangement hereinbefore described with reference to Figure 1. When
the three parts composing this priming chamber are put together the open end of the
cup E is closed by bending the edges finwards so as to form a support for the anvil B
and present a small central hole or vent at g. In this as in the preceding arrange-
ment a chamber is formed being closed on all sides except at the vent hole and in
which is contained the cap and fulminate, the explosion of the latter being produced
by its compression between the anvil and the bottom of the chamber.
The arrangement illustrated in Figure 3 comprises (1) a cylindrical cup F of
relatively thick metal (2) An anvil G in the form of an inner metallic cup in the
bottom of which a recess or chamber is formed by a stamping process for the reception
of the fulminate or priming C, the said recess presenting a nipple i forming the anvil
proper (3) A priming cap H made similar to the one hereinbefore described but
considerably shorter as indicated in the drawing. These three parts are first put
together as indicated at I after which the rim is formed as shown at k in such a
manner as to form a rim likewise on the inner cup or part G forming the anvil and
secure the latter in position in the cup F as indicated in the upper part of figure 3.
Figure 4 illustrates a method of fixing these priming chambers in a paper cartridge
case such as are used for sporting purposes. A hole is made in the metallic base of
the cartridge for the reception of the priming chamber in such a manner as to form
an inwardly projecting rim or edge which should project inwards as far as possible.
In compressing the paper cylinder by which the tubular case is connected to the
metal base a recess or space is formed for the prinring chamber A being of slightly
smaller diameter than the chamber containing the priming in order that the said
chamber may fit tightly when placed in position in the cartridge. The compression of

page_text: the paper and the elasticity of the edge or rim on the metal base ensure perfect
immunity from leakage.
In some cases in order to provide a further safeguard against possible leakage a
metal lining m figure 5 may be provided in the cartridge case.
This lining is per-
forated with a hole having inwardly projecting edges mm which lie snugly against
the priming chamber.
In
Figures 6 and 7 illustrate the application of the invention to metallic cases.
forming the recess for the priming chamber inwardly projecting edges are formed
being made as long as possible and of a tapering form as shown in the sections
(figures 6 and 7) so as to closely embrace (owing to their elasticity) the sides of the
priming chamber thus forming a joint which the pressure in the case merely tends to
tighten.
This improved system of priming is also applicable to the small cartridges used
in revolvers and to the large cartridges employed in quick firing guns as well as to
all intermediate sizes used in firearms or mitrailleuses or machine guns of all
descriptions.
It is evident that with this system of arranging the priming the manufacture of
cartridge cases proper is greatly facilitated. In the commonest form heretofore
employed, (figure 8) the recess for the priming in which the anvil is formed by
forcing up the metal presents certain difficulties in the manufacture and occasions
waste which is obviated in the improved forms indicated in figures 6 and 7. At the
moment of filling or charging the cases the interior is coated with a varnish for the
purpose of protecting the metal from the chemical action of the powder. This varnish
is applied by means of a rotating brush the extremity of which is not able to act
effectually on the base of the case owing to the projecting edges p, figure 8 of the
vent holes as usually formed. In the improved cartridge there is no such irregularity
of surface opposed to the action of the brush which is consequently enabled to do its
duty thoroughly on all the internal parts of the case.
This improved cartridge thus fulfils all the conditions hereinbefore described
namely. (1) The priming can be readily renewed. In fact the priming chamber
being cylindrical externally is kept in its place by friction only so that it can be
withdrawn or inserted without difficulty (2) No escape of gas can take place through
the cap or priming which is completely enclosed within the priming Chamber
(3) The bulging out of the cap is prevented owing to the thickness of metal that is
employed in making the cap piece containing the cap.
Having now particularly described and ascertained the nature of the said Invention
and in what manner the same is to be performed 1 declare that what I claim is.
First A central fire cartridge having a priming chamber closed on all sides with
the exception of a vent hole in the side within the cartridge the said chamber being
provided with a concealed cap containing the fulminate which is exploded by being
compressed between the bottom or end of the chamber and an anvil made separate
from or forming part of the chamber which is so arranged that the internal pressure
of the Gas tends to force the cap against the side of the chamber in such a manner as
to prevent any leakage or escape of gas substantially as hereinbefore described and
illustrated in the accompany drawings.
Second The arrangements and combinations of parts forming the improved central
fire cartridge substantially as hereinhefore described.