Year: 1885

page_text: I, PHILIP MIDDLETON JUSTICE of 55 and 56 Chancery Lane in the County of
Middlesex, Fellow of the Institute of Patent Agents do hereby declare the
nature of this invention a communication from abroad by the Costa Arms and
Ammunition Co. Incorporated of New York, United States of America to be as
follows:-
This invention relates to certain improvements in that class of fire arms provided
with spiral grooves which impart rotation to the projectile, and the invention
consists in providing the arm with grooves of such a character as will prevent the
stripping of the leads or wings from the projectile, insure a closer fit of the
projectile to the bore, prevent the escape of gas around the projectile, and impart a
greater initial velocity to the projectile.
In the construction of fire arms of this class it has heretofore been customary to
make the rifling grooves of uniform depth throughout from the breech to the
muzzle of the barrel, the result being that the projectile which fits the grooves as
it lies in the breech of the barrel becomes gradually loosened as it moves forward
in consequence of the wearing away of the wings or projections against the sides
of the grooves, so that the gases escape round the projectile and there is consider-
able loss of propulsive force, while the bore of the barrel becomes clogged by
the adhesion of portions of metal stripped from the projectile by the action of
the grooves.
This invention consists in preventing the stripping of the metal from the
projectile, by so constructing the barrel that the bottoms or bearing faces of
the grooves incline towards the axis of the barrel towards the front end, that
is so that the grooves become more shallow towards the muzzle of the gun and

page_text: -
preferably disappear or terminate within the muzzle, so as to leave a smooth bore
beyond the terminus of the grooves.
The result of this construction is that the projections upon the projectile instead
of being stripped therefrom are more and more compressed and condensed as the
projectile moves along the barrel, until they are crushed down against the body
which becomes absolutely cylindrical. As there is a constant compressing action
upon the projections the projectile throughout its entire travel is caused to fit
closely to the bore, so that there is no escape of gas and the projectile is thrown
from the arm with greater initial velocity than would otherwise be the case, and
this result would ensue even if the projectile fits the breech portion of the bore,
but loosely.
D
1
.

page_text: I, PHILIP MIDDLETON JUSTICE of 55 and 56 Chancery Lane in the County of
Middlesex Fellow of the Institute of Patent Agents do hereby declare the
nature of this invention (a communication from abroad by the Costa Arms and
Ammunition Co. Incorporated of New York, United States of America) and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This invention relates to certain improvements in that class of fire arms provided
with spiral grooves which impart rotation to the projectile, and the invention
consists in providing the arm with grooves of such a character as will prevent
the stripping of the leads or wings from the projectile, insure a closer fit of the
projectile to the bore, prevent the escape of gas around the projectile, and impart a
greater initial velocity to the projectile.
In the construction of fire arms of this class it has heretofore been customary
to make the rifling grooves of uniform depth throughout from the breech to the
muzzle of the barrel, the result being that the projectile which fits the grooves as
it lies in the breech of the barrel becomes gradually loosened as it moves forward
in consequence of the wearing away of the wings or projections against the sides of
the grooves, so that the gases escape round the projectile and there is considerable
loss of propulsive force, while the bore of the barrel becomes clogged by the
adhesion of portions of metal stripped from the projectile by the action of
the grooves.
This invention consists in preventing the stripping of the metal from the
projectile, by so constructing the barrel that the bottoms or bearing faces of
the grooves incline towards the axis of the barrel towards the front end, that is
so that the grooves become shallower towards the muzzle of the gun and preferably
disappear or terminate within the muzzle, so as to leave a smooth bore beyond the
terminus of the grooves.
The result of this construction is that the projections upon the projectile instead
of being stripped therefrom are more and more compressed and condensed as the
projectile moves along the barrel, until they are crushed down against the body
which becomes absolutely cylindrical. As there is a constant compressing action
upon the projections the projectile throughout its entire travel is caused to fit
closely to the bore, so that there is no escape of gas and the projectile is thrown
from the arm with greater initial velocity than would otherwise be the case, and
this result would ensue even if the projectile fits the breech portion of the bore,
but loosely.
The application of the invention to a breech loading rifle is illustrated in the
drawing in which
.
Fig. 1 shows the rifle with the barrel in section.
Fig. 2 is an enlarged transverse section on the line 1-2, Fig. 1.
Figa, 3 and 4 are diagrams.
A, represents the barrel, and a. a¹, two equidistant grooves which it will be

page_text: at a point x, within the muzzle, which beyond said point and to the end of the
barrel is a smooth bore.
The gradual diminishing depth of the grooves is illustrated in Figs. 3 and 4,
where it will be seen that the bearing face y of the groove although at all points"
parallel to the bore gradually approaches the said axis of the bore towards the
muzzle of the gun.
The invention although shown in connection with a rifle is applicable to all
forms of rifled fire arms.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim'is-
1. A fire arm provided with spiral grooves, decreasing in depth from the breech
towards the muzzle and terminating within the muzzle, substantially as set forth.
2. A rifled fire arm having grooves gradually diminishing in depth, the bearing
faces y of the grooves being parallel to the axis of the bore, substantially as
set forth.