Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
117769Z
Thiq illvent~on relates to ammunition Eor use in training exercises.
In militar~ training it is highl~ desirable that weapons should
function as realistically as possible without presenting a safety hazard.
ThusJ a suitable round of ammunition for training purposes is one which
will not project a bullet or debris which could endanger those taking
part in the exercise.
In order to simulate normal operation of a firearm as closely as
possible a training round should as far as possible produce the same
sound effect, the same recoil of the firearm, and in the case of an auto-
matic weapon should be capable of actuating the automatic mechanism inthe same way as the normal ammunition which the f~rearm is intended to use.
Various forms of training round have been used in the past with these ends
in view, but all have suffered from some disadvantage or another.
One method is to provide a round in which the brass cartridge case is
extended and crimped over at its forward end to approximate the overall
shape of a standard bulleted round. A round of this ~orm is rather diffi-
cult to manufacture in that the bullet form requires deep drawing down to
a narrow diameter. Also this form leaves a spent case which is consider-
ably longer than that of a standard round, and is therefore more difficult
to e;ect.
Another known method is to repiace the normal bullet by a wooden one,
the object being to ensure that the bullet disintegrates on firing~ This
type of practice round normally requires use of a special baffle at the
muzzle to confine particles of wood. If a standard cartridge case is
used the problem of ejection is overcome, but the need for a special
baffle can be inconvenient. Moreover, it is found in practice that even
when a baffle is used there'is a uanger of high veloc~ty wood splinters
escaping, and fragments of wood remaining within parts of the gun and
baffle must be cleaned out fairly often.
X
1177692
-2-
Ihe Applioant has alHo carried out 60me trials ueine a plA6tic6-
bodied cartridge case with ao integrally moulded 601id pl~tic~ bullet
attached thoreto by a weakened 6ection. Prim~ facie this arrRngement
ought to permit an inexpensive con6truction but in practice thi~ has been
found not to be ~o, ~artly because of the need to include a machined ~etal
primer case. A160~ the pla~tic case~ are readily deformed by firing and
pas6age through the loading and unloadin6 mechani6m Or the lirearm, 80
that ejection can be difficult and the mechanism tend~ to ~am. Also
debri6 from the plastic b~71et can tend to foul the parts of the firearm,
requiring frequent clearlnB.
There is th w n need for a training round which can create the
desired degree of reali6m ~ith the maxi~um possible degree of 6afety. It
is a Breat advanta~e if the trainin~ round can incorporate a 6tandard
cartridge ca6e, 60 that the need for 6pecial arrangements to manufacture
a 6pecial ca6e can be a~oided. In order to permit A 6mooth loading into a
6tandard fire~r~, ~Jhere appropriate from a 6tendard magazine, the o~erall
6hnpe of the rou~d 6hould be 6ubstantially the 6ame R6 that of a etandard
rou~d, but the bullet portion 6hould be such as
i) adequately to withstand an~ rough handlin~ it ~ay receiYe
up to ~hen it i6 ch~bered for firing; ~nd
ii) to be consumed a6 completely as po66ible on firing preferably
prior to exit from the muzzle, and certainly within a 6hort
distance from the ~uzzle.
Ihe practice round 6hould be capable of actuating any automatic or 6elf
loading 0echani6m ~rithout the need for any 6pecial attachment, except of
cour6e that a blank firin~ attachment which throttle~ the muzzle ~ill
probably always be nece6sary for this purpose.
~ ccording to one a6pect, the pre6ent invention 6eck6 to provide a
blank trainin8 round ~hich possesses at lea6t 60me of the cn3racteristic6
3 outlined kereinbefore as beinB desirable.
According to the present invention, there is provided a round of
ammunition for use in training comprising a cartridge case, a quantity
of combustible propellant material within the case, and a bullet
:, ,' .
- .
.
-3- 11~2
fitted at the forward end of the case to seal the propellant material
within the case, the bullet consisting solely of a core of foamed polyure-
thane and an external skin of unfoamed polyurethane, whereby on firing the
round the propellant material ignites to produce high energy gases which
5 act directly on the bullet to project .the bulle~ from the oRslng ~nd to
di~nt~ te the bullet.
Conveniently, the core and Ekin of the bullet are an integral
moulding.
The thickness of the 6kin should rormally be in the range 0.02 to
0.10 mm, preferably 0.04 to 0.05 mm.
The calibre of the round will normally not be greater than lO mm.
The invention also provide6, according to another aspect thereof,
a device for feedin~ ammunition to ~n automatic firearm, said device
containing a plurality of round~ of ammunition in accordance with the
invention.
The bullet can be of ogival form, or can have opposite ends each
of oeival form.
According to a 6till further a6pect thereof, the invention provides
a method of operating an automatic firearm, ~aid firearm being
capable of firing in rapid succession a plurality of rounds of am~unition
each said round bein8 of a particular size and external shape and
comprising a cartridge case of a particular size and external shape, the
firearln being capable of ejecting automatically each cartridge case
after firing and automatically preparing another round for firing, wherein
the method of operating comprises supplying to the firearm in succession
for firing a plurality of rounds of ammunition of the said size and external
shape each said round comprising a cartridge case of the said and external
shape and containing a quantity ofcombustible propellant material within the
case, and a bullet fitted at the forward end of the case to seal the propellant
material within the case, the bullet consisting solely of a core of foamed
polyurethane and an external skin of unfoamed polyurethane whereby on firing
the round the propellant material ignites to pro~duce high energy gases which
act directly on the bullet to project the bullet from the casing and to
disintegrate the bullet.
,~.\
117769Z
-3a~
The invention will now be described by way of example only, with
reference to the accompanyin~ drawi~g6, of which
Figure 1 is an axial 6ectional view Or a round of ~mmunition in
accordance with the invention, and
S Figure 2 is an fixial section of an alternative form of polyurethane
bullet in zccordance with the invention.
As 6hoYn in Figure 1, the round comprises a bra~s cartridge case 1
of 6tandard form a6 used for live ammunition, and a con~umable bullet 2
of ogival form compri~ing a core of foamed polyurethane 3 and an integral
.
.
~1776g2
-4--
~kin 4 of unfoamed (ie fully dense) polyurethane. The polyurethane
material contain6 2~ lamp black for colouring and hence greater realism.
The bullet 2 has a chamfered rear end portion 5 to facilitate its
insertion into the open forward end of the cartridge case 1. The bullet
is fitted to the cartridge case by cr~mping the forward end portion 6
thereof after insertion of the bullet in like manner to fitting of a
standard bullet in a live round. The material of the bullet 2 i8 thus
deformed in~ard6 and a seal formed between the bullet and the case.
The cartrid~e case 1 i6 provided in the u6ual way with a cannelure 7
to facilitate loading and unloadiDg, and a pri~er cap 8 received in a
reces6 9 in the case 1. The primer cap 8 comprises a ca6ing 10 which is
a pre66 fit in the recess 9, containing a quantity of pri~ary explosive 11
and closed by a closure member 12 having an intesral anvil 13.
The cartridge case is partially filled with a quantity of propellant
14 which i6 considerably less than is used for a normal live round, fGr
example ~ the nor~al weight. The rece66 9 communicate6 with the interior
of the cartridge case 1 through a bore 15. No solid material is interposed
bet~een the explosive charge and the bullet.
When the primer cap 8 is struck as by the firing pin of a firearm,
the primary explosive 1 is ~ipped between anvil 13 and casing 10, and
hence detonates; the closure member 12 is ruptured; and a flame passes
through the bore 15 to ignite the reduced propellant charge 14. This is
a normal sequence of events on firing a round of ammunition. The pressure
of Bas generated by the burning propellant charge causes the bullet to
separate from the case 1 and to be projected down the barrel of the firearm.
However, because of the special 0aterial and construction of the
bulle' 2, the bullet is con6umed during the course of its passage along the
barrel or within a 6hort distance after exit therefrom. The mechanism by
wnich the bullet i~ consumed is not wholly under6tood but it is thought
that the cxplo6ive force of the propellant either vaporises or 6hatters
the bullet into minute particles which readily burn in the hot wash of
propellant gas. Polyurethane requires ve,-y little oxygen for its
combu6tioD, a factor which may assi6t the bullet in being consumed.
1177692
~5-
The bullet 2 itfielf is conveniently and cbeaply made by a low pres~ure
moulding process in which the polyurethane material i6 foamed in 6itu in a
mould, the charge placed in the mould beine such a quantity iD relation to
the mould 6ize tha~ on foaming the charge i8 confined by the mould 6urface
~o that a thin den6e ~kin of polyurethane i6 formed on ~he mould flurrace
with an inner core of rigid polyurethane foam. CoJ~itions muot be ouch
that the skin iæ not unduly thick~ otherwi6e the skin may fail to di6in-
te6rate or vaporise thoroughly on firing, 60 that relatively large
particle6 of the 6kin are either projected a 6ubstantial distance or
remain within to foul part6 of the firearm. Factors which affect the
kin thickne66 are the mass of the charge in relation to the mould 6ize
the nature of the foam-producting mixture (ie the charge), the temperature
of the charge at entry to the mould, and the temperature of the mould.
The &kin should be sufficiently thick to with~tand any rougb handling
which can be aDticip~ted prior to firing - eg in the action of chambering
and any automatic loading or feeding from a magazine. These factors mean
the 6kin thickne6s ~hould normally be in the range 0.02 to 0.10 mm with
thickne6se6 less than o.o6 mm preferred. In m~ny case6 the be~t compromise
will be obtai~ed with a skin thickne66 of 0.04 to 0.05 mm.
In practical tests, bullets of 5.56 mm calibre have been moulded
from Components A and B of I~ofoam 120, a commercial trade product of the
Ebxenden Chemical Company. The mixture of Component6 h and B is capable
of generating polyurethane foam, and include6 carbon black for the purpose
of inhibiting the degradation in natural light which otherwise occurs in
polyurethane. The 5.56 mm calibre bullet6 were mouldcd using between 0.07
and 0.09 gm of the mixture of Components A and B. The mould wa6 at room
temperature, and the mixture charged into the mould at 25C. It will be
obser~ed that the ma6s of polyurethane forming a bullet i6 v~ry small.
In firing tests, training round~ of the for~ herein descri~ed with
reference to the figure and incorporating the 5.56 mm bullets ju6t
de6cribed were loaded inio a magazine and fired from an automatic weapon
with a blank firing attachment (ie a muzzle throttle). The automatic
feed, loading and ejection mechanisms were all found to operate
6atisfactorily and the sound and recoil effects were similar to those of
a no~mal live rou~d. A paper screen placed 5m in ,ront of the muzzle of
the firearm sho~ed no damage or marking. Little or no fouling of any part
of the gun or blank firing attachment was noted.
. ~ ' .
' .
~17769Z
--6-
It will thus be app~rent that ~rain~ng rounds in ~ccordance with
the invention can be economic to produce, requiring only a 6tandard
cartridge ca6e with 8 cheaply 00ulded polyurethane bullet. The bullet
i6 6afely con6umed in firine. The round can be u6ed in a 6tandard
feeding device 6uch a6 a maGazine or feed belt for u~e with a ~tandard
automatic weapon, the only ~odification required beinB the addition Or
a 6tandard blank firing attachment where autoc~tic or 6elf-loading
operation i6 required - this being nece6sary with all known forms of
blank round. With thi6 modification, full self-loading and automatic
action canbe retained. Little or no fouling of the gun mechanism or the
blank firing attachment can be expected.
It can be anticipated that the invention will be equally 6ucce6sful
with otner calibre of 6mall arms, although it i6 though that with calibre6
in exce6s of 10 mm it may prove impo6sible to design a round so that the
bullet i6 adequately consumed within an acceptably ~hort di6tance.
In Figure 2 there is 6hown an alternative form of bullet 20 which can
replace the bullet 2 shown in Figure 1. Like the bullet 2, the bullet 20
ha6 a core 21 of ri6id polyurethane foam and skin 22 of unfoamed polyurethane
moulded integrally therewith. The bullet 20 compri6es opposite end portions
20 2~, 24 each of 6imilar ogival form linked by a short cylindrical portion 25.
The bullet 20 is thu6 of the general 6hape of two standard bullet6 joined
back to back. In u6e the cylindrical portion 25 is beld by crimping the
forward portion 6 of the cartridge ca6e leaving the 6ame cxterl~l 6hape
to the round a6 shown in Figure 1.
Thi6 arrangement can have a number of practical advantage6. In auto-
~atic a66embly of tne rounds, it doe6 not ~atter which way round the bullet
20 is fed and offercd for a6sembly to the cartridge ca6e 1. Thi6 6implifies
mechanical handling. Furthermore, ~ith a bullet 2 of the same 6ize a6 a
normal bullet in a live round, but the mas6 of propellant 14 reduced, a
relatively lar6er 6pace remain6 for the propellant to ~hift about in the
case. Thi6 can lead to inefficient combu6tion of the propellant on firing.
The "double-ended" bullet 20 partially fill6 the cartrid~e c&se, 60 ~ome-
what re6training the propellant. Houlding very low ma6s bullets po6e6
60me difficulty, and the use of a larger, double bullet, ea6e~ the
~5 difficulty to a certain extent.
Other modification6 within the 6cope of the invention ~ill be evident
to tho6e 6killed in the art.
,:
'
.
