AN IMPROVEMENT OR IMPROVEMENTS IN BREECH LOADING SMALL ARMS
Year: 1883

page_text: LETTERS PATENT to John Field Swinburn of Birmingham in the County
of Warwick Gun Manufacturer for an Invention of AN IMPROVEMENT OR
IMPROVEMENTS IN BREECH LOADING SMALL ARMS
PROVISIONAL SPECIFICATION left by the said John Field Swinburn at the
Office of the Commissioners of Patents on the 10th January 1883.
JOHN FIELD SWINBURN of Birmingham in the County of Warwick Gun
Manufacturer "AN IMPROVEMENT OR IMPROVEMENTS IN BREECH LOADING SMALL
ARMS
"
My invention has reference to breech loading small arms of the kind commonly
called drop down guns and pistols that is guns and pistols in which the open
breech ends of the barrels are raised from the break off for charging and shut down
and fixed against the face of the break off during discharge.
My invention consists in constructing and arranging in the manner hereinafter
described the lever on the tang of the break off and the parts immediately
connected therewith by which the prolongation of the rib between the barrels is
fixed down in the recess in the break off. By my invention the bearing surfaces
of the lever and parts immediately concerned in the fastening down of the barrels
are increased to an extent unattainable by the ordinary construction of the said
parts and great security thereby attained.
The long arm of the lever differs in no essential respect from that of the lever
ordinarily employed but has great breadth at its junction with the short arm, the
short arm tapering from its junction with the long arm and having a tongue like
figure. The short arm is of less thickness than the long armn the under surfaces of
both arms being situated in the same plane but the upper surface of the short arm
being in a lower plane than that of the long arm
The pin or centre on which the lever turns is not situated symetrically that is
midway between the sides of the lever but is situated on the edge of the broadest
part of the lever. In consequence of this position of the centre on which the lever

page_text: turns the short arm on being disengaged by the motion of the long arm from the
slot in the end of the rib partakes of the cross motion of the ordinary lever and
the longitudinal motion of those fastenings in which the lever is made to operate
a bolt
The broad short arm of the lever works under a strap or bridge on the break off 5
and when the barrels are fixed down and the short end of the lever fills the slot in
the end of the rib the said short end of the lever is supported by the said bridge
This great extent
not only at the rear but also at the sides of the end of the rib
of bearing surface gives great security and rigidity to the connected parts.
The long arm of the lever has on its underside a recess containing the spring by 1
which its return motion and snapping action are effected.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Field Swinburn in' the Great Seal Patent Office on the
4th July 1883.
Jonx FIELD SWINBURN of Birmingham in the County of Warwick, Gun
Manufacturer. "AN IMPROVEMENT OR IMPROVEMENTS IN BREECH LOADING SMALL
ARMS
"
My invention has reference to breech loading small arms of the kind commonly
called drop down guns and, pistols, that is, guns and pistols in which the open
breech ends of the barrels are raised from the break off for charging and shut down
and fixed against the face of the break off during discharge.
My invention consists in constructing and arranging in the manner herein after
described the lever on the tang of the break off and the parts immediately
connected therewith by which the prolongation of the rib between the barrels is
fixed down in the recess in the break off. By my invention the bearing surfaces
of the lever and parts immediately concerned in the fastening down of the barrel +
are increased to an extent unattainable by the ordinary construction of the said
parts and great security thereby attained.
The long arm of the lever differs in no essential respect from that of the lever
ordinarily employed but has great breadth at its junction with the short arm, tho
short arm tapering from its junction with the long arm and having a tongue like
figure. The short arm is of less thickness than the long arm the undersurfaces of
both arms being situated in the same plane but the upper surface of the short arm
being in a lower plane than that of the long arm.
The pin or centre on which the lever turns is not situated symetrically that is,
midway between the sides of the lover but is situated on the edge of the broadest
part of the lever. In consequence of this position of the centre on which the lever
turns the short arm on being disengaged by the motion of the long arm from the
slot in the end of the rib partakes of the cross motion of the ordinary lever and
the longitudinal motion of those fastenings in which the lever is made to oporate
a bolt. The broad short arm of the lever works under a strap or bridge on the
break off and when the barrels are fixed down and the short end of the lever fills
the slot in the end of the rib, the said short end of the lever is supported by the
said bridge not only at the rear but also at the sides of the end of the rib. This
great extent of bearing surface gives great security and rigidity to the connected
parts.
The long arm of the lever has on its underside a recess containing the spring by
which its return motion and snapping action are effected.
I will now proceed to describe with reference to the accompanying Drawing the
manner in which my invention is to be performed.
Figures 1 and 2 represent in side elevation a breech loading double barrel drop
down gun containing a top lever fastening constructed according to my invention,
Figure 1 representing the barrels fastened down for the discharge of the gun and
Figure 2 the same unfastened for loading the gun; Figure 3 represents an end
elevation of the body of the gun; Figure + represents a plan of upper side of the
body of the gun and top lever fastening and Figure 5 a plan of the underside of
the said body; Figure 6 represents a side elevation and plan of underside of the
top lever fastening; Figure 7 represents a side elevation of the body of a gun with
which an undersliding bolt is combined with my improved top lever fastening;
Figure 8 represents the top lever fastening and the actuating part of the under
bolt and Figure 9 represents the underbolt separately.

page_text: The same letters of reference indicate the same parts IN OH SOVCIAL Figures
the drawing.
a are the barrels of the gun and b is the prolonged rib between the barrels in a
recess c in which prolonged rib the top lever fastening hereinafter described takes
for fastening down the barrels; d is the break off and e is the body of the gun
containing the internal hammers and their main springs. The lever fastening is
marked and g in the drawing, f being the long arm of the top lever and g the
short arm which takes into the recess c in the prolonged rib to fasten down the
barrels; is the pin or centre on which the lever turns; i is the strap or bridge on
the break off under which strap or bridge the short arm g of the lever passes and
by which it is supported when in its fastening position. In a cut away part or
box in the long arm f of the lever is the spring by which the return and
snapping action of the lever is effected one of the arms of the spring bearing against
the fixed pin Z on the tang. The spring in the long arm of the lever constitutes
no part of my present invention the said spring being described and claimed in a
prior patent granted to me
It will be seen by an examination of the plan Figure 4 and the plan of the
separate view of the top lever Figure G, that the long arm f of the top lever has
great breadth at its junction with the short arm g and that the said short arm g
has also great breadth so as to give it a tongue like figure the said short arm g
tapering from its junction with the long arm f. It will also be seen that the lower
surface of the two arms f, gare in the same plane but the upper surface of the
short arm is in a lower plano than that of the long arm f. The pin or centre h on
which the lever turns is not situated midway between the sides of the lever but is
situated at the edge of the broadest part (see Figure 6). By centering the top
lever in this way its short arm g on being disengaged by the motion of the long
arm from the slot'c in the rib b to unfasten the barrels partakes of the cross motion
of the ordinary lever and the longitudinal motion of the bolt in those fastenings -in
which a lever is used to operate a bolt. The combined motion described which the
broad short arm g of the lever takes when moved to fasten and unfasten the barrels
will be readily traced by an examination of Figure 4
The opening m (see Figure 3) below the strap or bridge i in which the broad
short arm g of the top lever works has nearly the figure of the said short arm and
when the lever is in its fastening position the said short arm besides nearly filling
the said opening completely fills the slot c in the end of the rib. It will be
seen by an examination of Figure 4 that the rear end as well as the sides of the
broad short arm g of the top lever are supported by the bridge or strap i.
By constructing the fastening parts in the manner described and illustrated the
.bearing surfaces of the short or acting arm of the top lever as well as the long or
operating arm of the said lever are much increased and great security in the
fastening is thereby attained.
My improved top lever fastening may be used to actuate an underbolt in the
manner represented in Figures 7. 8 and 9. In this case I prolong downwards the
axish on which the top lever turns and apply to its bottom end a cam or arm n
which works between the fork p on the bottom bolt g, the said bolt q working in
the body and taking into a recess in the lump on the underside of the barrels in the
ordinary way. When the long arm f of the top lever is turned aside to unfasten
the barrels at the prolonged rib the cam or arm n at the same time withdraws the
bottom bolt q so as thereby to simultaneously unfasten the barrels at top and
bottom.
I have represented and indicated in the gun shown in Figures 1 and 2 of the
drawing mechanism for cocking the gun on the opening of the barrels for charging
them and also safety mechanism operated automatically on the opening of the
barrels but ns these parts have been fully described and claimed by me in the
specifications of prior patents I do not think it necessary here to describe them.
My improved top lever fastening hereinbefore described and illustrated is
applicable to tho fastening of drop down pistols as well as to drop down guns.
1

page_text: Having now described the nature of my invention and the manner in which the
same is to be performed I wish it to be understood that I claim as my invention of
"An improvement or improvements in breech loading small arms'
"
The new or improved top lever fastening for fastening down the barrels of drop
down guns and pistols herein before described and illustrated in the accompanying
Drawing; that is to say, giving the long arm of the top lever fastening at
its junction with the short arm a breadth equal to or about equal to that of the
tang at its junction with the break off and making the said short arm taper from
its junction with the said long arm so as to give it the broad or tongue like figure
represented, the top lever thus constructed being centred at the edge of its broadest
part so that on the motion of the lever the broad short arm partakes of the cross
motion of the ordinary lever combined with the longitudinal motion of the ordinary
sliding bolt operated by a top lever, the several parts being constructed and
working substantially as and for the purpose described and illustrated; whether
the said top lever fastening be used alone or in combination with an underbolt
In witness whereof I the said John Field Swinburn have hereunto set my
hand and seal this third day of July in the year of our Lord one thousand eight
hundred and eighty three.