Note: Descriptions are shown in the official language in which they were submitted.
~ WO95/10752 2 1 7 3 9 ~ 8 PCT/GB94/02228
RECOIL REDUCER WAD FOR SHOTGUN AMMUNITION
The present invention relates to a device for
reducing recoil in weapons. It is applicable to all
types of weapons in which the ignition of gunpowder, or
cordite, or the like, is employed to propel a projectile
or projectiles in a forward direction.
A known shotgun cartridge is as shown in the
accompanying Fig. 1. A casing 10 encloses, in sequence,
a primer 12 held by an end cap 13, a charge 14, and wad
16, and a quantity of shot 18. The shot is retained in
place by a cap 20. The cartridge is fired by striking
the primer 12, causing ignition thereof and hence
ignition of the charge 14. Gases are produced by this
15 latter ignition under high pressure, which propel the
rear face 22 of the wad 16 in a forward direction. Thiæ
initially causes crushing of the wad 16 and then forward
acceleration of the shot 18, and rupture of the cap 20.
The purpose of wad 16 is to protect the shot 18 from too
20 sudden acceleration.
Such cartridges are described in FR 2362362, FR
2251775, US 4151799, and US 3722412.
The present invention provides a round of ~mml~n; tion
containing within a casing a primer cartridge, a charge,
25 and at least one projectile forward of the charge,
wherein there is an unoccupied gap or a gap occupied by
non-supportive material between the charge and the rear
internal face of the round. It is preferred that the
WO95/10752 2 1 7 ~ 9 6 ~ pcTlGBs~lo2228
charge is enclosed within a jacket which has forward
portion and a rear portion, adapted such that on ignition
of the charge the rear portion of the jacket travels
rearwards into the region between the charge and the rear
internal face of the round where its kinetic energy is at
least partly absorbed by a kinetic energy absorbing
means. The kinetic energy absorbing means may comprise a
tapered pillar projecting from a rear internal face of
the round toward the rear jacket portion, and a
corresponding opening in the rear jacket portion which
fits about the tip of the column. Then, during rearward
motion of the rear jacket portion, the opening is
progressively widened by the tapered pillar and this
deformation of the material immediately around the
opening absorbs kinetic energy. Alternatively, or in
addition, a crushable material can be provided in the
space between the rear internal face of the round and the
rear jacket portion. A suitable material is expanded
polystyrene.
It is necessary to provide a striking face of the
primer in the rear external face of the round, to allow
actuation of the round by a firing pin. It is also
necessary for the efflux of the primer to contact the
charge in order to ignite it. To satisfy these design
requirements, it is possible either to employ an elongate
primer capable of extending from the rear face of the
round to the charge, or to provide a duct to direct the
efflux from~the primer to the charge. Such a duct can be
~ WO95/10752 2 t 7 3 ~ 6 8 PCT/GB94/02228
provided within the above-mentioned column. It is
preferable that such a duct, where provided, is
internally fluted to improve the flow of efflux from the
primer.
To prevent "suck-back" of the rear jacket portion
into the weapon barrel after firing, circumferential ribs
can be provided on an internal face of the round or on an
external surface of the column, (where provided). Thus,
during rearward motion of the rear jacket portion under
pressure of the propellent gases, the rear jacket portion
passes over these ribs and is then retained against
subsequent forward motion, preventing it from leaving the
cartridge and becoming lodged in the barrel.
The present invention also provides, in a second
aspect, a shotgun round having a charge, a quantity of
shot, and an internal member for separating the charge
and shot, the member being generally cylindrical and
internally divided by a dividing member into a charge
receiving region and a shot receiving region wherein
either;
l. the cylindrical member has a circumferential
recess on an outer face thereof in register with the
dividing member, and the dividing member has an axially
centred circular recess on a face thereof, or
2. the dividing member has an axially extending
protrusion projecting into the charge receiving area.
The first option of the second aspect allows slight
radial expan~sion and contraction of the member, which
WOs5/l0752 ~ 6 b PCT/Gs9J/02228
gives a better sealing action to the inside of the barrel
during travel therealong, without excessive friction.
The second option directs the efflux of the primer more
evenly about the charge receiving area and hence gives
better burning of the charge.
The second aspect of the present invention also
relates to such an internal member ~E se, for use in the
manufacture of a shotgun cartridge.
Embodiments of the present invention showing its
application to shotgun cartridges will now be described
by way of example, with reference to the accompanying
drawings. It is of course to be understood that the
present invention is not limited to shotgun cartridges
and is e~ually applicable to other types of ~m~nl tion.
In the drawings:
Fig. 1, already described, is a prior art shotgun
cartridge;
Fig. 2 is a cross-section through a shotgun cartridge
according to a first embodiment of the present invention;
Figs. 3A and 4 are, respectively, a cross-sectional
side view and a top view of the column and rear jacket
portion according to a second embodiment of the present
invention, while Fig 3B is a cross-sectional side view of
the column and rear jacket portion of Fig. 3A
incorporated into a cartridge, the recess of the rear
jacket portion being alternatively positioned;
Figs. 5A and 6 are, respectively, part cross-
sectional s~de view and a top view of a third embodiment
7 ~ ~ ~ Q
WO95/10752 ~7~ V PCTIGB94/02228
of the present invention, while Fig. 5B is a cross-
sectional side view of the embodiment of Fig. 5A
incorporated into a cartridge, the recess of the rear
jacket portion being alternatively positioned.
Fig. 7 is a side view of the column and rear jacket
portion of the first and second embodiment of the present
invention, after firing the of round;
Fig. 8 is a cross-sectional view of the base portion
of a cartridge, in a further embodiment;
Fig. 9 is a cross-sectional view of the base portion
of a cartridge, in a yet further embodiment;
Fig. 10 is a sectional side view of a front jacket
portion according to a fourth embodiment of the present
invention;
Fig. lOA shows part of the embodiment of Fig. 10
following firing of a charge; and
Figs. 11 and 12 show alternative arrangements of the
fourth embodiment incorporated into a shotgun cartridge.
In the Figures, like parts are denoted by like
reference numerals.
In the shotgun cartridge of the Fig. 2, a shotgun
casing 10 has an end cap 13 holding a primer 12. The
primer 12 commllnicates with an internally fluted duct 22
formed axially within a tapering column 24. The duct 22
leads to a charge 14 enclosed by a jacket consisting of a
forward jacket portion 28 and rear jacket portion 30.
The rear jacket portion 30 has an aperture 32 which fits
snugly about the end of the column 24. The forward
wossllo7s2 PCT/GB9~/02228
q 6 ~ ~
jacket portion 28 has a rearwardly directed axial
projection 34 in the shape of a truncated circular
pyramid Ahead of the forward jacket portion 28 is a
quantity of shot (not shown~ in the region 18. The shot
would normally be retained within the casing by a cap
(not shown) similar to the cap 20 of Fig. 1.
The cartridge is fired by striking the external
surface of the primer 12, causing explosion thereof.
Flames travel along the duct 22 to the charge 14. The
projection 34 promotes uniform distribution of the flames
about the charge 14 and thus gives near simultaneous
ignition of the entire charge. Expansion of the gases
produced by ignition of the charge 14 drive the forward
jacket portion forward and the rear jacket portion
rearward. The forward motion of the forward jacket
portion 28 causes expulsion of the shot in the
conventional fashion. Rearward motion of the rear jacket
portion 30 is gradually arrested by absorption of its
kinetic energy through deformation of the opening 32 as
it is driven down the taper of the column 24.
Hence, the rearward momentum corresponding to the
forward momentum of the shot is transmitted to the rear
jacket portion 30, rather than the weapon itself. Since
the energy of this motion is absorbed in deformation of
the jacket portion, a significantly reduced recoil is
produced. Hence, a better shooting performance can be
obtained due to decreased fatigue or nervousness on the
part of the~firer. Alternatively, a larger charge can be
WO95110752 ~ ~ 7 ~ q 6 g PCT/GB94102228
employed to give a greater muzzle velocity with no
substantial increase in recoil over the prior art
cartridge.
Various modifications and improvements are possible
to the design of Fig. 2, which are illustrated in Figs. 3
to 6.
In Figs. 3A and 4, the forward surface of the rear
jacket portion 30 has an axially centred ring-shaped
recess 3~ (an alternative being shown in Fig. 3B where
the recess 36 is in rearward surface). This recess 36
increases the radial flexibility of the rear jacket
portion 30, the effect of which is to take up the
increase in diameter of the opening 32 without causing an
increase in the overall diameter of the rear jacket
portion 30. Thus, bulging of the cartridge during firing
is inhibited, allowing easier removal of the cartridge
from the barrel of the weapon. Also shown in Fig. 4 are
radially extending grooves 38, which allow better
distribution of the flames from the primer 12 about the
charge 14.
Figs. 5A and 5B show an alternative to the circular-
cross section column 24 of Figs. 2 to 4, being a column
of polygonal cross section (or of round cross section,
this being particularly suited for manufacture by
injection moulding), the column could conveniently be
manufactured as an integral part of an injected, moulded
or drawn shotgun cartridge.
Fig. 7 shows the column and rear jacket portion of
WO 95/10752 ~ 6 8 PCT/GB9-~/02228
Figs. 3 and 4 after firing. As can be seen, the rear
jacket portion 30 is retained against forward motion by
the rib 26. Forward motion of the rear jacket portion 30
into the barrel of the weapon is undesirable since this
could cause bulging of the barrel on firing of a further
round.
It is, in fact, undesirable for any part of the
recoil reducer to travel forward into the barrel of the
weapon. Therefore, to anchor the column 24 to the base
of the cartridge, the column 24 is formed with a dovetail
section 39 which engages with a corresponding recess
provided on an internal face of the cartridge.
Additionally, as shown in Fig. 13, the primer 12 may
be formed with external ribs 60 which engage and grip the
inner wall of the duct 22 to further resist forward
movement of the inner jacket portion, and/or the recoil
device.
Figs. 8 and 9 show alternative arrangements for
restraining forward motion of the column 24 into the
barrel. In this arrangement, the column 24 has a recess
37 which fits around a corresponding annular dovetail 39
on the base of the cartridge. Alternatively, of course,
the column 24 could be formed integrally with the
cartridge 10, as shown in Fig. 2.
Fig. 9 also shows the use of hollow crushable rings
of plastics within the region around the column 24, as an
energy absorbing means. Alternatively, expanded
polystyrene`can be employed, as solid rings or spheres or
~ WO95/10752 2 ~ 73~ 6 8 PCTIGB94/02228
the like.
With reference to Figs. 10 to 12, here will be
described a fourth embodiment of the invention. A
forward jacket portion 28 consists of a generally
cylindrical structure 40 divided into a shot retaining
portion 42 and a charge retaining portion 44 by a
dividing portion 46. As described earlier with reference
to Fig. 2, the dividing portion 46 has a member 34
projecting into the charge retaining portion to promote
uniform distribution of flames from the primer (not
shown).
The dividing member further has an axially centred,
annular projection 48 which extends into the shot-
retaining portion 42, and a central, generally conical
lS projection 34 which extends into the charge-ret~;n;ng
portion 44.
Additionally, there is provided a charge support 31
disposed between the cartridge base 13 and the jacket
portion 28. The charge support 31 (which is separate
from the jacket portion 28) comprises a platform member
32 into which the charge is received which is supported
on a recoil-absorbing structure which is, in turn,
carried on the base plate. The recoil absorbing
structure comprises two toric members 116 of resilient
material in each of which is an air space 41. A duct 22
extends axially through the cartridge base 13 and the
toric members 116 to provide a flame path between a
primer (not~shown in Figs. 10 to 12) and the platform
WO95/10752 ~ pcTlGBs~lo2228
member 32.
When the cartridge of this embodiment is discharged,
recoil energy is absorbed by resilient compression of the
toric members 116 (as shown in Fig. lOA), so reducing the
recoil transmitted to the weapon itself.
Figs. 11 and 12 illustrate alternative constructions
of cartridges embodying the above described components.
As shown in Fig. 11, the charge support 31 could be
formed integrally with the base plate of the cartridge.
This is made possible since the reduction in recoil
forces resulting from the invention allows the base plate
to be formed from a wider range of materials (including,
for example, plastics, which may, for example, be drawn
or injection moulded) than hitherto possible.
Alternatively, as shown in Fig. 12, a substantially
conventional base plate 13 may be used. In this case, it
is highly desirable to provide means to anchor the charge
support 31 in the cartridge case. With reference to Fig.
12, this may be achieved by forming an inwardly-directed
nip 50 in the case, the internal diameter of which is too
small to allow the charge support 31 to pass freely
therethrough. Alternatively, a dovetail formation (as
described above) may be employed to this end.
