IMPROVEMENTS IN GUN-BARRELS to be as follows:
Year: 1885

page_text: I HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co, Patent Agents,
Southampton Buildings in the County of Middlesex, do hereby declare the nature
of invention for "IMPROVEMENTS IN GUN-BARRELS to be as follows:-
"
This invention relates to choke-bored gun-barrels, that is to say, gun-barrels
whereof the bore is contracted or reduced at the muzzle, and its chief object is to
so construct such guns that elongated bullets can be advantageously used there-
with.
Gun-barrels of this class have heretofore been made with smooth bores, but, by
grooving or rifling the choke or contracted part of such barrels, considerable
advantages can be obtained with respect to accuracy of aim either with shot or
with round or elongated bullets.
.
The present invention, therefore, consists essentially in forming, in the choke or
contracted part of a gun-barrel, any suitable number of spiral grooves, the pitch or
inclination of which must be varied, as usual, according to the diameter of the
bore, the length of the bullet, and the position of its centre of gravity. The pitch
or inclination of the said grooves must, moreover, be proportionate to the length of
the choke.
The difference in calibre between the two parts of the barrel should, by
preference, be about one millimeter or one twenty-fifth (+) of an inch, and the
choke or contracted part of the barrel should be about one inch long. The choke
or contracted part of the barrel may be provided with any suitable number of
grooves of any desired width. It will be found very advantageous to provide it
with seven grooves and to make these grooves narrower than the lands between
them. The said grooves should not extend to the larger part of the bore, and are,
therefore, made about from four thousandths (100) to six thousandths (1000) of
an inch in depth. By constructing the barrel in this manner, a bullet which fits
the larger part of the bore will receive a certain amount of compression when it
reaches the rifled part of the barrel.
The said grooves are made either semi-circular, square or of other suitable
shape in transverse section; by preference, however, they are made semi-circular
or of other rounded form. Better results are, moreover, obtained by making them

page_text: slightly deeper at their driving edge or side, that is to say, at the edge or side
which imparts the rotatory impulse to the bullet. They may also, if desired, be
made deeper at the rear end than at the forward end of the choke or contracted
part of the bore.
In using a gun having a barrel formed as above described, it is most
advantageous to employ an elongated bullet having one or more annular grooves
or channels in the cylindrical part thereof, which grooves or channels may, if
desired, be filled with a lubricant. The diameter of the cylindrical portion of
this bullet should be equal, or nearly equal, to that of the larger part of the bore'
of the gun.
Guns constructed with the improved choke-bored barrels above described have,
at sporting ranges, the accuracy of a rifle of the same calibre.
Hardened bullets may, with advantage, be employed in these guns.

page_text: improvements in Gun-barrels.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake, and Co, Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature
of my invention for "IMPROVEMENTS IN GUN-BARRELS" 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 choke-bored gun-barrels, that is to say, gun-barrels
whereof the bore is contracted or reduced at the muzzle; and its chief object is to
provide for enabling elongated bullets to be advantageously used with choke-bored
guns.
Gun-barrels of this class have heretofore been made with smooth bores, but, by
grooving or rifling the choke or contracted part of such barrels, considerable
advantages can be obtained with respect to accuracy of aim either with shot or
with round or elongated bullets.
The present invention, therefore, consists essentially in forming, in the choke or
contracted part of a gun-barrel, any suitable number of spiral grooves, the pitch or
inclination of which must be varied, as usual, according to the diameter of the bore
of the gun, the length of the bullet to be used, and the position of the centre of
gravity of the said bullet. The pitch or inclination of the said grooves must,
moreover, be proportionate to the length of the choke.
The difference in calibre between the two parts of the barrel (for a 12-bore gun)
should, by preference, be about one millimeter or one twenty-fifth () of an inch,
and the choke or contracted part of the barrel should be about one inch long.
It has been found very advantageous to provide the choke or contracted part of
the barrel with seven grooves, and to make these grooves narrower than the lands
between them. But the number and width of the grooves may be varied, if
necessary or desirable. The said grooves should not be of sufficient depth to
extend to the larger part of the bore; they are preferably made about from four
thousandths (100) to sixth thousandths (10%) of an inch in depth. They are
made either semi-circular, square, or of other suitable shape in transverse section ;
by preference, however, they are rounded. Better results are, moreover, obtained
by making each groove slightly deeper near its driving edge or side (that is to say,
the edge or side which imparts the rotatory impulse to the bullet) than at any
other point in its width. They may also, if desired, be made to increase in depth
from the forward end to the rear end of the choke or contracted part of the bore.
In the accompanying drawing.
Figure 1 is a longitudinal central section of part of a gun-barrel with the present
improvements applied thereto, and
Figure 2 is an end elevation of the said gun-barrel.
These figures are drawn to an enlarged scale in order to clearly show the form of
the grooves.
a indicates the larger part of the bore, and a¹ the choke or contracted part
thereof. a² is the conical portion which unites these two parts of the bore.
b, b are the grooves, which are of such depth that they do not extend to the
larger part of the bore, but terminate near the rear end of the conical portion a*.
It will be seen that these grooves are deepest near the driving edge or side b¹.

page_text: When a choke-bored gun having its barrel rifled in the manner above described
is used with a bullet which fits the larger part of the bore, the said bullet will
receive a certain amount of compression when it reaches the rifled part of the bore,
and will be rapidly rotated as it leaves the muzzle.
It is most advantageous to employ, with the improved gun, an elongated bullet
having one or more annular grooves or channels in the cylindrical part thereof,
which grooves or channels may, if desired, be filled with a lubricant. The
diameter of the larger parts of this bullet should be equal, or nearly equal, to
that of the larger part of the bore of the gun.
Moreover, hardened bullets may be used with advantage.
Guns constructed with the improved choke-bored barrels above described have,
at sporting ranges, the accuracy of a rifle of the same calibre. The said invention
therefore provides for ensuring greater accuracy of aim than has heretofore been
attainable with choke-bored guns.
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
First. A choke-bored gun-barrel which is rifled or provided with spiral grooves
in the choke or contracted part of the bore, for the purpose specified.
Second. The modification of the invention which consists in making each groove
deeper near its driving edge or side than at any other point in its width, as above
specified.