U.S. patent application number 10/203551 was filed with the patent office on 2003-08-07 for training ammunition.
Invention is credited to Saxby, Michael Ernest.
Application Number | 20030145754 10/203551 |
Document ID | / |
Family ID | 9885095 |
Filed Date | 2003-08-07 |
United States Patent
Application |
20030145754 |
Kind Code |
A1 |
Saxby, Michael Ernest |
August 7, 2003 |
Training ammunition
Abstract
The invention provides a training cartridge (304) having a
peripheral fire primer (306) and a gun modified to fire the
cartridge. The combination of modified gun and peripheral fire
cartridge avoids the potentially adverse consequences that could
arise if live ammunition and training ammunition were to become
inadvertently confused or mixed up by preventing the firing of live
centre fire ammunition.
Inventors: |
Saxby, Michael Ernest; (East
Sussex, GB) |
Correspondence
Address: |
LAHIVE & COCKFIELD
28 STATE STREET
BOSTON
MA
02109
US
|
Family ID: |
9885095 |
Appl. No.: |
10/203551 |
Filed: |
November 6, 2002 |
PCT Filed: |
February 8, 2001 |
PCT NO: |
PCT/GB01/00515 |
Current U.S.
Class: |
102/446 |
Current CPC
Class: |
F42B 8/02 20130101 |
Class at
Publication: |
102/446 |
International
Class: |
F42B 008/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2000 |
GB |
0002767.2 |
Claims
1. A method of modifying a gun to prevent it from firing live
ammunition with a centre fire primer but permit the firing of a
rimfire primer training cartridge, which method comprises replacing
a barrel of the gun such that a centre firing pin of the gun is not
aligned for centre firing of a cartridge received in the barrel,
but is aligned for firing of a rimfire primer of the training
cartridge.
2. A method as claimed in claim 1 characterised by selecting a gun
having a centre fire firing pin and replacing the barrel of the gun
with a barrel in which the breech is offset such that the centre
fire firing pin can impact against and fire the rimfire primer
training cartridge but not a centre fire cartridge.
3. A method according to claim 2 characterised in that the bore of
the barrel is inclined relative to the barrel axis.
4. A method of modifying a gun to prevent it from firing live
ammunition but permit the firing of a rimfire primer training
cartridge, which method comprises replacing a centre fire firing
pin with a rimfire primer firing pin.
5. A gun modified according to the method of any of claims 1 to
4.
6. A combination of a modified gun as claimed in claim 5 and one or
more training cartridges having a rimfire primer and configured to
be shot from the modified gun.
7. A training cartridge with a rimfire primer configured for firing
by the gun of claim 5.
8. A training cartridge as claimed in claim 7 characterised by a
rimfire primer cup set into the rear end thereof.
9. A training cartridge as claimed in claim 7 or claim 8
characterised in that the cartridge is expandable upon firing,
expansion of the cartridge serving to urge a rear surface of the
cartridge rearwardly against a breech block of a gun to initiate
recycling of the gun.
Description
[0001] This invention relates to improved training ammunition and
to a method of modifying a gun to fire the training ammunition.
BACKGROUND OF THE INVENTION
[0002] Low powered training cartridges are known, and examples of
such cartridges are disclosed in PCTGB98/00620, PCT/GB99/02859,
PCT/GB99/02556, GB 9819928.4 and U.S. Pat. No. 5,492,063. Training
cartridges are characterised in that they impart much less energy
to a projectile than a live ("killing") round. Thus, whereas a live
round may impart 800 ft/lbs of energy to a bullet and a shotgun may
impart as much as 1000 ft/lbs of energy to the shot, training
cartridges are much less energetic. For example, the energy
imparted to a projectile by a training cartridge is typically less
than 5 ft/lbs and more usually less than 4 ft/lbs. The term
"training cartridges" as used herein therefore refers to such low
energy cartridges, unless the context indicates otherwise.
[0003] The aforementioned training cartridges typically contain
only a primer and do not contain a conventional amount of
propellant. Consequently, they must be carefully designed to ensure
that there is sufficient energy both to recycle a weapon and eject
a projectile such as a bullet. Many training cartridges, see for
example the cartridges disclosed in the patent documents supra, are
of the expanding type in which the body of the cartridge comprises
a "piston and cylinder " arrangement. With such cartridges, part of
the energy of the primer is used to force the piston and cylinder
apart (i.e. expand the cartridge) and drive the rear end of the
cartridge back to recycle the weapon, and part of the energy is
used to discharge the projectile from the front end of the
cartridge. Careful control of gas flow within the cartridge is
required in order to make sure that the projectile is discharged at
a consistent and appropriate velocity and that the weapon is
recycled at every firing.
[0004] All (so far as the Applicants are aware) current training
ammunition, and most live military ammunition, is of the centre
fire variety. Exceptions are certain 0.22.thrfore. (5.56 mm) rounds
generally used in target shooting (and occasionally in military
training) which are of the rimfire type. Live cartridges of the
centre fire variety generally have a primer carried in a cup or
"can" set into the rear end of the cartridge. However, with live
rounds of the rim fire type (f or example the 0.22" rounds referred
to above) the primer is not carried in a cup or can but is held in
the hollow rim of the cartridge case itself.
[0005] FIG. 1 shows a sectional elevation through the primer for a
centre fire cartridge of the type typically used in live military
ammunition. The primer comprises a can 2 formed from, for example,
nickel plated brass, and containing a suitable pyrotechnic primer
material 4. The can is held in a recess in the centre of the rear
surface (not shown) of the cartridge. An anvil 6 is set into the
front of the can 2 to close the can and retain the primer in place.
As the anvil is inserted into the can, the protruding central part
6a of the anvil greatly compresses the primer to create a
compressed region 4a which is highly sensitive to shock. The region
4a which is sensitive to shock has an approximate width I, and this
represents the impact area for the firing pin of a centre fire
weapon. Thus, a centre fire firing pin will impact against the
impact area and further compress the primer between the wall of the
can and the anvil thereby detonating the primer. However, it will
be appreciated that the firing pin of a rimfire weapon would impact
against the can outside the impact area I and hence would not
detonate the primer.
[0006] Although training cartridges that are constructed to provide
consistent low energy discharge of bullets are generally safe per
se, safety problems can arise when live killing cartridges are
inadvertently mixed with or substituted for low powered training
cartridges. As stated above, all of the known existing training
cartridges use centre fire type of primers which are very similar
and often identical to the types of primers used in the equivalent
live killing cartridge for a particular gun type. Attempts have
been made to prevent confusion between the two types of cartridge
by modifying the gun so that it will not fire the cartridge type
usually fired from the gun, but will only fire a training
cartridge. Unfortunately, this safety feature can sometimes be
bypassed by using a different live cartridge type which, when
chambered, fits the gun, or by using damaged live cartridges. In
such circumstances, firing live cartridges rather than training
cartridges can result in serious injury or death.
[0007] It is an object of the present invention to provide a
solution to the aforementioned problems by preventing live killing
cartridges from being fired inadvertently in place of training
cartridges.
SUMMARY OF THE INVENTION
[0008] The present invention makes use of peripheral fire primers
in the training cartridges, and a gun modification which allows the
firing pin of the gun to strike the periphery (i.e. rim) of the
primer which fires a cartridge. If any type of centre fire
cartridge is fitted into the gun whilst the conversion is fitted,
the firing pin cannot set off the centre fire primer as the point
of impact of the firing pin is beyond the sensitive part of the
centre fire primer. Thus, the present invention prevents the
standard centre fire military ammunition from being fired
inadvertently instead of low velocity training ammunition.
[0009] Accordingly, in one embodiment the invention provides a
training cartridge having a peripheral fire primer.
[0010] The primer typically takes the form of a cup or "can" which
is set into the rear end of the cartridge. The cup typically has a
hollow peripheral rim in which the primer material is located, the
primer material being in a compressed state and highly sensitive to
shock. The primer material can thus be detonated when the
peripheral rim of the can is impacted by a firing pin. This
arrangement is in contrast to conventional live rimfire cartridges
( i.e. 0.22 " calibre) in which the primer material is located in
the rim of the cartridge itself rather than the peripheral rim of a
cup set into the rear of the cartridge.
[0011] The training cartridges of the invention are preferably
expandable upon firing, expansion of the cartridge serving to urge
a rear surface of the cartridge rearwardly against a breech block
of a gun to initiate recycling of the gun.
[0012] For example, in one embodiment, there is provided an
expandable training cartridge configured to enable a projectile
(e.g. a bullet) to be mounted in or on a nose portion thereof, a
gas passage though the nose portion providing communication between
the cartridge interior and the projectile. The cartridge has valve
means for controlling propellant gas flow through the gas passage
to the projectile, and a movable member which upon firing is
propelled rearwardly from the cartridge against a breech block of
the firearm by the pressure of propellant gas within the cartridge
so as to recycle the firearm. The valve means is preferably
arranged to close in order to stop or substantially reduce the flow
of propellant gas through the said gas passage after the projectile
has been fired from the cartridge, thereby to facilitate rearwards
propulsion of the movable member.
[0013] The precise nature of the training cartridge is not critical
but, for example, the training cartridge can be of the general type
described in any one of PCT98/00620, PCT/GB99/02859, PCT/GB99/02556
and GB 9819928.4, but with an appropriately modified primer. The
diameter of the training cartridge is generally greater than the
diameter (usually approximately 0.375" (9 mm)) of live 0.22" (5.65
mm) rounds although the training cartridge may carry a 0.22" (5.65
mm) bullet or projectile, and may be provided with a primer of a
diameter typically associated with a 0.22" (5.65 mm) round.
[0014] In general, the primer is the only pyrotechnic material in
the cartridge; i.e. there is no propellant other than the primer.
The primer is such that the cartridge produces an energy of less
than 4 ft/lbs, more preferably less than 3 ft/lbs, for example less
than 2.5 ft/lbs, and most preferably 2 ft/lbs or less.
[0015] In another aspect, the invention provides a method of
modifying a gun to prevent it from firing live ammunition but
permit the firing of a rimfire primer training cartridge, which
method comprises (i) replacing a centre fire firing pin with a rim
fire firing pin and/or (ii) replacing a barrel of the gun such that
a centre firing pin is misaligned for centre firing of the
cartridge but is aligned for rim firing of the cartridge, but
excluding the modification of a gun capable of firing live 0.22"
(5.56mm) cartridges by replacing the centre firing pin with a
rimfire firing pin..
[0016] In a further aspect, the invention provides a method of
modifying a gun to prevent it from firing live ammunition but
permit the firing of a rimfire primer training cartridge other than
a 0.22" (5.56 mm) calibre cartridge, which method comprises
replacing a centre fire firing pin with a rim fire firing pin.
[0017] In another aspect, the invention provides the combination of
a training cartridge having a rimfire primer and a gun that has
been modified to fire a rimfire primer-containing training
cartridge.
[0018] In a further aspect, the invention provides a peripheral
fire primer for use in a cartridge as hereinbefore defined, the
primer comprising a cup for setting into the rear end of the
cartridge, the cup having a hollow peripheral rim containing
compressed primer material.
[0019] In a further aspect, the invention provides a method of
modifying a gun to prevent it from firing live ammunition but
permit the firing of a rimfire primer training cartridge, which
method comprises selecting a gun having a centre fire firing pin
and replacing the barrel of the gun with a barrel in which the
breech is offset such that the centre fire firing pin can impact
against and fire the rimfire primer training cartridge but not a
centre fire cartridge.
[0020] In a still further aspect, the invention provides a gun
having a centre fire firing pin and a barrel in which the breech is
offset such that the centre fire firing pin can impact against and
fire a rimfire primer cartridge but not a centre fire primer
cartridge.
[0021] Which modification is selected will depend upon the nature
of the gun. For pistols or other guns which have sliding or
removable barrels, a barrel conversion may offer the simplest means
of modifying the weapon. On the other hand, if the barrel is fixed,
and the breech block is slidable, as with most rifles and machine
guns, then the simplest conversion is to modify or change the
firing pin to a rimfire firing pin.
[0022] In the case of a barrel modification, the centre fire firing
pin of a gun prior to modification is arranged such that it strikes
at a location which is central with regard to the bore or breech of
the barrel, i.e. the centre line of the firing pin is coincident
with the centre line of the barrel. After modification in
accordance with the invention, the centre line of the bore of the
barrel is offset relative to the centre line of the firing pin.
This means that a firing mechanism incorporating a centre fire
firing pin will not impact against the sensitive central area of a
centre fire cartridge but will instead impact against the rim.
Thus, the modification to the barrel allows rimfire training
cartridges to be fired but prevents the corresponding centre fire
live ammunition from being detonated.
[0023] A further advantage of the offset of the bore is that the
bore can be inclined with respect to the axis of the barrel thereby
providing a means of correcting the trajectory of the low velocity
projectile without the user of the gun needing to make any changes
to his normal sighting.
[0024] In cases where it is more appropriate to modify the firing
pin, rather than the barrel, the centre line of the firing pin may
still be aligned with the centre line of the bore of the barrel but
the modified pin typically has a laterally extended leading end
portion, the laterally extended leading end portion having a
leading surface profiled such that it impacts against the rim of a
rimfire primer but not against the centre of a centre fire primer.
The laterally extended leading end portion can be laterally
extended in one plane or in two planes.
[0025] For example, when it is extended in one plane, the end of
the pin can take the form of a flat spade-like structure that
slides in a slot cut into the breech block. The flat spade-like
structure may have one or two (and preferably two for balance)
forwardly oriented projections at the edges thereof for impacting
against the rim of a rimfire primer but not the central impact area
of a centre fire primer..
[0026] When the leading end portion of the modified firing pin is
laterally extended in two planes, it can, for example, have a
cylindrical form. In such a case, the leading surface can have one
or more (preferably more than one) discrete projections protruding
forwardly therefrom, or the leading surface can be provided with a
forwardly projecting annular rim having a diameter such that it
impacts against the impact area of a rimfire primer but not the
impact area of a centre fire primer.
[0027] In order to reduce still further the possibility of a centre
fire primer being detonated by the modified pin (for example as a
consequence of a piece of particulate matter or debris between the
firing pin and cartridge), the region of the leading surface
between or inwardly of the projection(s) can be cut away, at least
over the area that would overlap with the impact area of a centre
fire primer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The invention will now be illustrated, but not limited, by
reference to the particular embodiments shown in the accompanying
schematic drawings, FIGS. 1 to 9.
[0029] FIG. 1 is a side sectional elevation through a centre fire
primer.
[0030] FIG. 2 is a side sectional elevation through a rimfire
primer.
[0031] FIG. 3 is a schematic elevation of a conventional
arrangement of a centre fire primer in a gun fitted with a centre
fire firing pin.
[0032] FIG. 4 is a schematic elevation of a conventional
arrangement of a rimfire primer in a gun fitted with a rimfire
firing pin.
[0033] FIG. 5 illustrates schematically part of a standard centre
fire pistol having a barrel containing a centre fire primer
cartridge.
[0034] FIG. 6 illustrates schematically the centre fire gun of FIG.
5 but wherein the barrel has been replaced by a modified
barrel.
[0035] FIG. 7 illustrates a standard rifle fitted with a centre
fire firing pin and containing a centre fire primer cartridge.
[0036] FIG. 8 illustrates the rifle of FIG. 7 but with a modified
firing pin.
[0037] FIG. 9 illustrates an explosive blank cartridge having a
peripheral fire primer.
DETAILED DESCRIPTION OF THE PERFERRED EMBODIMENTS
[0038] A peripheral fire primer for use in a cartridge according to
the invention is shown in FIG. 2 and comprises a can 102, the
closed end of which is formed to provide a hollow peripheral rim
area 103. A pyrotechnic primer composition 104 is placed in the can
and the can is spun thereby forcing the pyrotechnic material into
the hollow peripheral rim area 103. With the primer of FIG. 2, the
impact area I' is annular in shape and extends around the
peripheral rim of the primer. As can be seen from FIGS. 1 and 2
together, for cartridges of the same calibre, there will be a dead
zone S between the impact region I of a centre fire primer, and the
impact region I' of a peripheral fire region in which any impact
will not detonate the primer. When a cartridge containing the
primer of FIG. 2 is placed in a weapon having an appropriately
configured and aligned firing pin and the weapon is fired, the
firing pin strikes impact area I' and compresses the pyrotechnic
composition between the two walls 103a and 103b of the hollow rim
region 103, the shock imparted to the pyrotechnic composition
causing it to detonate.
[0039] Referring now to FIG. 3, there is shown a conventional
arrangement of a gun 200 having a centre firing pin 202, a training
cartridge 204 being inserted into the breech thereof. In this case,
in accordance with conventional practice, the cartridge 204 has a
centre fire primer 206 fitted into the end thereof, the primer
being of the type shown in FIG. 1. It will be noticed that the
centre line L1 of the firing pin 202 is coincident with the centre
line L2 of the barrel of the gun.
[0040] In FIG. 4, there is shown an arrangement in which a gun 300
has been modified to provide it with a peripheral fire firing pin
302 which is offset from the centre line of the barrel so that it
can fire a training cartridge 304 having a peripheral fire primer
306 of the type shown in FIG. 2.
[0041] As indicated above, a problem with centre fire training
cartridges is that on occasions training cartridges and live
killing ammunition can become confused. In order to avoid this
problem the invention provides a training cartridge which is
detonated by impact on the peripheral rim of the primer, and makes
use of a gun which is specially modified to allow use of the
peripheral fire primer.
[0042] FIG. 5 shows a standard centre fire pistol into which has
been inserted a cartridge having a centre fire primer. The
arrangement shown in this Figure corresponds to FIG. 3 except that
the barrel of the pistol is removable. FIG. 6 shows a modification
of the gun shown in FIG. 5. As demonstrated in FIG. 6, the gun is
still provided with a centre fire firing pin 410 which, with a
normal gun barrel, would allow the firing of centre fire
cartridges. However, in order to prevent centre fire cartridges
from being fired, the gun is converted by replacing the normal gun
barrel with a gun barrel 412 in which the bore 414 is offset. As
can be seen from FIG. 6, the bore 414 is inclined at an angle a
with regard to the axis 16 of the barrel. The centre line of the
bore 414 is also inclined with respect to the centre line of the
firing pin 410.
[0043] If a training cartridge having a peripheral fire primer is
inserted into the breech, the relative geometry of the gun barrel
and firing pin are such that the firing pin can fire the cartridge.
On the other hand, if a centre fire cartridge (for example a live
killing cartridge) is inserted into the gun barrel, the firing pin
410 will fail to strike the centre fire impact area 318, and hence
the cartridge will not detonate. Thus, the modification of the
invention greatly enhances the safety in that it prevents live
killing ammunition from being inadvertently mixed with training
ammunition.
[0044] A further advantage of the arrangement shown in FIG. 6 is
that it can enable training ammunition to be used more accurately.
One of the problems with training ammunition is that the low
velocity means that the bullet will often fall away before it
reaches a target, and consequently there will be a tendency for the
user to compensate for this by aiming above the target. Thus
shooting at targets using low velocity ammunition can be less
realistic than is desirable. With the gun barrel arrangement shown
in FIG. 6, the user of the gun can fix his sights on the target in
the normal way, and the angle of the bore, rather than the angle of
the barrel, provides the necessary correction to enable the
projectile to reach its target. Thus, the range of the training
ammunition is much closer to the range of normal live killing
ammunition.
[0045] The modification shown in FIG. 6 is particularly suited to
pistols since in many cases the barrel of a pistol can be removed
fairly easily. However, the barrels of rifles are typically fixed
and hence a barrel modification of the type shown in FIG. 6 would
involve somewhat more complex alterations to the gun and would not
be a practical proposition.
[0046] Therefore, with rifles and machine guns and other firearms
with fixed non-sliding barrels, it is easier to modify the firing
pin and this is demonstrated in FIGS. 7 and 8.
[0047] FIG. 7 shows a part of a conventional rifle equipped with a
centre firing pin and having a centre fire training bullet inserted
in the breech thereof. FIG. 8 illustrates the same rifle but
wherein the firing pin has been modified. Thus the firing pin is no
longer pin-shaped but instead has a leading end which is extended
laterally to give a spade-like shape. The leading surface of the
leading end has forwardly oriented projections 512 at either edge
thereof, the projections being aligned with the impact region 514
of the peripheral fire primer 513 of the cartridge. The central
part 516 of the leading end is recessed, the width of the recess
being at least as great as the width of the impact area of the
centre fire primer 318. In use, when the weapon is fired, the
projections 512 on the edges of the leading end of the modified
firing pin impact against the sensitive impact region of the
peripheral fire primer to detonate the primer. However, if a
cartridge (e.g. a live killing round) having a centre fire primer
is inadvertently inserted into the gun, it will not be detonated.
The safety of the modified firing pin arrangement shown in FIG. 8
is further enhanced by virtue of the recessed central region 516
which ensures that centre fire primers cannot accidentally be
detonated as a result of the presence of particles of debris
between the firing pin and cartridge.
[0048] The modified firing pin of FIG. 8 can be fitted, for
example, by shortening an existing firing pin, cutting a thread on
the end thereof, and fixing the threaded end into a suitably
profiled end piece. The circular channel or opening in which the
firing pin normally slides is machined out to form a slot to
accommodate the spade-like shape of the end piece.
[0049] FIG. 9 illustrates an explosive blank cartridge that can be
fired in the modified gun of FIG. 8. The blank cartridge comprises
a casing 602 closed at its nose 604 and containing an explosive
material 606. The rear end of the blank cartridge has a flange 608
to enable the spent cartridge to be extracted from the breech in
the usual manner. Thus far, the blank cartridge is of conventional
construction. However, the cartridge differs from conventional
blank cartridges in that the primer 610 set into the centre of the
rear of the cartridge is a peripheral fire primer. The primer 610,
which can be of the form shown in FIG. 2 or an appropriate
modification thereof, comprises a cup or can 612 having a hollow
peripheral rim 614 containing compressed primer material. In use,
the off centre firing pin 616 of the gun impacts against the
peripheral rim 614 thereby detonating the primer material which in
turn detonates the explosive material 606. Expanding gases created
by the detonation of the primer and explosive material burst
through the nose 604 in the usual manner to give a realistic
bang.
[0050] The foregoing examples illustrate merely some of the ways in
which the invention can be put into effect, and it will readily be
apparent that numerous modifications and alterations can be made to
the arrangements shown in the accompanying drawings without
departing from the principles underlying the invention. All such
modifications and alterations are intended to be embraced by this
application.
* * * * *