Year: 1888

page_text: Date of Application, 5th July, 1888
Complete Specification Left, 30th Apr., 1889
Complete Specification Accepted, 1st June, 1889
I, FRANCIS EDWARD DYKE ACLAND late Captain Royal Artillery, of 53 Parliament
Street, in the City of Westminster, do hereby declare the nature of this invention to
be as follows:-
This invention has for its object improvements in rifling guns.
At the present time it is usual to make the rifle grooves of uniform width from
breech to muzzle and the projectile is usually provided with a copper ring to take the
rifling. When the charge is fired this ring at once becomes moulded to the rifle
grooves.
As the projectile passes along the bore this copper ring is subjected to wear.
Soon the projection on the ring which originally fitted the groove ceases to do so;
its width becomes less and then the gases under pressure pass through the space which
is left void from the width of the projection being less than that of the rifle groove.
Erosion of the gun then results. To prevent this I so form the rifle grooves that as
they proceed from breech to muzzle they get progressively narrower and shallower
and so the change of form in the copper ring as it traverses the bore is compensated
by a like change in form in the grooves which receive it. After the projectile leaves
the gun its flight is to some extent impeded by the projections on the copper ring
which
corresponding to the grooves of the rifling-by making the grooves in the
I have described but decreasing in width and depth more rapidly than is requisite to
compensate wear I am able considerably to reduce the dimensions of the projections
on the ring of the projectile as the same leaves the gun or even to allow the projectile
to leave the gun without such projections whereby the accuracy of its flight is
improved.
way

page_text: I, FRANCIS EDWARD DYKE ACLAND, late Captain Royal Artillery, of 53 Parliament
Street, in the City of Westminster, do hereby declare the nature of this invention
and in what manner the same is to be perforined to be particularly described and
ascertained in and by the following statement:—
This invention has for its object improvements in rifling guns.
At the present time it is usual to make the rifle grooves of uniform width from
breech to muzzle and the projectile is usually provided with a copper ring to take
the rifling. When the charge is fired this ring at once becomes moulded to the rifle
grooves.
As the projectile passes along the bore this copper ring is subjected to wear.
Soon the projection on the ring which originally fitted the groove ceases to do so;
its width becomes less and then the gases under pressure pass through the space which
is left void from the width of the projection being less than that of the rifle
groove.
Erosion of the gun then results. To prevent this I so form the rifle grooves that as
they proceed from breech to muzzle they get progressively narrower and shallower
and so the change of form in the copper ring as it traverses the bore is compensated
by a like change in form in the grooves which receive it. After the projectile leaves
the gun its flight is to some extent impeded by the projections on the copper ring
corresponding to the grooves of the rifling-by making the grooves in the way which
I have described but decreasing in width and depth more rapidly than is requisite to
compensate wear I am able considerably to reduce the dimensions of the projections
on the ring of the projectile as the same leaves the gun or even to allow the projectile
to leave the gun without such projections whereby the accuracy of its flight is
improved.
Rifled grooves becoming progressively narrower from breech to muzzle can be
obtained among other ways by using the ordinary rifling bar and rifling machine which
is set to the necessary angle or curve.
As soon as the cutting operation commences in the bore of the gun, that end of the
copying bar which corresponds to the breech can be moved through the required
distance from its previous position, so that, the angle between its new position and its
old, shall correspond with the angle which is formed by the broadest section of the
grooves and the first cut or narrowest part.
If BAC in the diagram Figure 1 is the angle at which the rifling bar is set at the
commencement, BA D will be the angle at which it finishes, and CAD will correspond
to that part of the rifling which is reduced in width from breech to muzzle.
To make the rifled grooves become progressively shallower from breech to muzzle
a boring bar such as shown in longitudinal and transverse sections at Figures 2 and 3
may be used.

page_text: This boring bar A is hollow and provided with an inner bar B; divided into two
parts one part marked B cylindrical, and the other square in section and marked C.
The square part C turns with the boring bar A whilst the cylindrical part B may be
turned within the boring bar by a series of change wheels. The square part C is
connected with the cylindrical part B by a screw B, cut with a fine thread so that
when the cylindrical part B is turned the square part C is caused to travel endwise a
certain distance within the boring bar.
The cutter E can only be moved in the bar in a direction at right angles to the
axis of the bar, its movement in this direction is controlled by an inclined lug F which
projects from the square part (and which passes through the cutter E so that the
cutter may be protruded or withdrawn by moving the square part C end wise within
the bar and in this way the grooves formed by the cutter may be made deeper at the
breech than at the muzzle.
The progressive difference in the depth of the grooves can be regulated by :―
I. The inclination of the lug F to the axis of the bar.
II. The pitch of the screw which connects the square part C with the cylindrical
part B, and
III. The arrangement of the change wheels on the machine.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
A gun with its rifle grooves made progressively narrower and shallower as they
proceed from breech to muzzle.