Note: Descriptions are shown in the official language in which they were submitted.
lO9Z440
This invention relates to improvements in the amm-
unition art and, specifically, to ammunition cartridges of the
type having a plastics cartridge case, i.e. a case that is made,
at least in a predominant portion, of a synthetic polymer compos-
ltlon and where the lower end portion of the cartridge case is pro-
vided with a bottom insert made of a metal. The term "lower end"
relates to that end of the cartridge case which is opposed to the
projectile-bearing or projectile imitation-bearing end of the
cartridge.
Cartridges of this type are known and have been
disclosed, for instance, in Swiss Patent 326,592. Cartridges of
this type are used in large quantities as blank rifle cartridges
in which the head end of the cartridge case continues into the im-
itatlon shape of a plastics projectile which constitutes an integr-
al part of the cartridge case and is furnished at its upper end
with a notch or similarly formed predetermined rupture point.
¦ The use of a plastics material for ammunition cart-
¦ridge cases offerSconsiderable advantages over usual metal cases
¦in regard to cost and production, but necessitatesa bottom insert
¦of metal which is suitable as a groove or edge for engaging the
usual cartridge extractor and ejector and for receiving and hold-
ing a detonator or percussion cap.
109Z440
A prlor art bottom insert of this type is a gener-
ally cylindrically shaped, solid metal component having an open-
ing for receiving the detonator cap, an external groove for inter-
action with the cartridge extractor, and a generally cylindrical
upper end portion with its external surface grooved in the manner
of a dowel for anchoring inside the wall of a plastics cartridge
case. Generally, such bottom inserts are made from aluminum by
machining as relatively large thicknesses of material are requir-
ed in the cartridge bottom. Thus, production of conventional all-
metal bottom inserts for plastics cartridges tends to be relatlve-
ly costly both in view of the comparatively large mass of metal
required and the costs of producing the inserts by conventional
machining techni~ues. Insertion of such metal inserts into a
plastics cartridge case can present problems such as ruptures of
the walls of the plastics cartridge case. Further problems in
connection with ammunition cartridges of the type having a plast-
ics case for blank cartridges or projectile-bearing cartridges
are encountered in regard to the projectile-llke end portion or
the Fonnection of the projectile and the plastics cartridge case.
Accordingly, it is the main general object of this
invention to provide for improvements in connection with blank or
live rifle and gun ammunition cartridges of the type having a
_ 3 _
1092440
plastics cartridge case.
~ n important specific object is a novel type of ln-
sert for ammunition cartridges having a cartridge case made of a
plastics material so as to decrease both the amount of metal used
for the insert and the costs of producing the inserts.
Another object is an improvement of structure and
function of blank and live ammunition rlfle or gun cartridges that
have a cartridge case made of a plastics material.
Yet another object is an improved method of produc- -
ing bottom inserts for ammunition cartridge cases made of a plast-
ics material.
Other objects will become apparent as the specific-
ation proceeds.
It has been found that the above and further objects
can be achieved according to the invention by means of a novel
cartridge bottom insert that includes a metal bottom element in-
tegrally connected to a plastics sleeve element, and by certain
modifications of the cartridge case with regard to the wall struct
ure and the projectile imitation or projectile-bearing end of the
ammunition cartridge.
109"410
According to a first general embodiment, this in-
vention provides for an ammunition cartridge suitable as blank or
live ammunition for rifles, said cartridge comprising a plastics
cartridge case, i.e. a rifle or gun case consisting, at least in a
predominant cartridge case wall portion, of a synthetic organic
plastics material and having a lower end portion for receiving and
holding a cartridge bottom insert; said cartridge bottom insert
being a composite unit structure comprising a metal bottom element
irmly secured in a plastics sleeve element. In general, the metal
bottom element includes a chamber for receiving a detonator cap
and is provided wlth two coaxial flange means or the like later-
aIly projecting rims having different diameters and being inter-
connected by a tubular portion. Preferably, the metal bottom ele-
ment is a shaped integral structure made of a sheet metal capable
of being formed by deep-drawing while the plastics sleeve element
is a generally rotationally symmetrical structure that surrounds
the upper portion of the metal bottom element and comprises at
least one means for engagement with an inner wall portion of the
plastics cartridge case as well as an aperture connecting the de-
tonator cap-receiving chamber of the metal bottom insert with a
charge-receiving portion of the cartridge case.
According to a second embodiment, the invention pro-
vides for a blank ammunition cartridge having a plastics cartridge
case, the lower end portion of which is closed with a cartridge
_ 5 _
109Z4~0
bottom insert and wherein the other end portion is shaped as an-
imitation projectile having a predetermined rupture point and an
axial length of not more than 25 ~ of the total axial length of
said ammunition cartridge.
According to a third embodiment, the invention pro-
vides for an ammunition cartridge having a plastics cartridge case
provided with a cartridge bottom insert, wherein the inner wall
of the cartridge case is provided with a plurality of elongated
ribs for controlling volume and packing of the charge.
In a preferred form of this third embodiment, an ex-
terior wall portion of the plastics cartridge case is provided
with a plurality of grooves for improved cartridge extractability
from the cartridge chamber of a weapon. Preferably, the ribs and
the grooves extend in a direction parallel to or helically around
the longitudinal cartridge axis.
- According to a fourth embodiment, the invention pro-
vides for a live ammunition cartridge having a plastics case with
a projectile protruding therefrom and a bond-control coating pro-
vided at the interface between the projectile and the plastics
cartridge case. If the projectile is made of a metal, the bond-
control coating is of the bond-improving type. For projectiles
made of a plastics material, the bond-control coating is of the
type that prevents an undesired interbonding of the plastics pro-
jectile and the plastics cartridge case. With either type of pro-
jectile a shoulder wall portion may be provided within the plast-
ics case for defining the position of the projectile.
' - 6 -
~ 1092~40
Preferably, the plastics projectile has a lower pro-
jectile portion situated within the plastics case and having a
larger diameter than the upper projectile portion that protrudes
from the plastics case for improved projectile guidance upon fir-
lng without impeding introduction of the projectile-bearing cart-
ridge into the cartridge chamber of a weapon.
It is to be noted that the cartridge bottom insert
of the second, third and fourth embodiment of the inventive amm-
unition cartridge preferably is the novel integral composite hav-
ing a metal bottom element firmly anchored in a plastics sleeve
element as specified in the first embodiment but a conventional
all-metal insert may be used as well.
According to a further embodiment, the invention
provides for a method of manufacturing an ammunition cartridge
with a plastics cartridge case having a lower end portion for re-
ceiving and holdlng a composite bottom insert including a metal
bottom element and a plastics sleeve element by (a) forming an
integral metal bottom element by deep-drawing of a metal sheet,
(b) forming the composlte bottom insert by anchoring the metal
bottom element in the sleeve element, (c) providing a detonator
cap within the metal bottom element, and (d) introducing the com-
poslte insert into the lower end portion of the plastics cartridge
case. Preferably, the charge will be introduced into the cartridge
case prior to introducing the bottom insert.
1092440
Exemplary embodiments of the invention will now be
described by means of the drawings in which:
Fig. 1 is a sectional view of the lower end portion
of an inventive cartridge illustrating a preferred insert
structure as the bottom closure of the plastics cartridge
case.
Fig. 2 is a sectional view of the lower end portion
of an inventive cartridge having a modified insert structure.
Fig. 3 is a sectional view of the lower end portion
of another modification of the inventive cartridge comprising
a modified insert.
Fig. 4a, 4b are sectional views of an inventive
cartridge case provided with a projectile imitation prior
to introduction of the bottom insert, and
Fig. 5a, 5b are sectional views of the top end portion
of a projectile cartridge.
In Fig. 1 the lower end portion of a plastics
cartridge case 14 (indicated in broken lines with the central
and upper cartridge case portions broken away for a sim~lified
presentation) is closed by means of a composite cartridge
bottom insert comprising the metal bottom element 10 that
consists of two coaxial disc- ................................
.~ ,
, , - 8
lO9Z440
like parts or annular flanges 101, 102 and of a tubular or hollow
cylinder member 104 interconnecting the flanges. Flange 101 const-
itutes the actual cartridge bottom, the upper rim or edge portion
of which is exposed for the engagement of a conventional cartridge
extractor. Flanges 101, 102 and the interconnecting tubular member
104 enclose a generally cylindrical chamber 100 for receiving and
holding a conventional detonator or percussion cap, not shown in
the drawings.
Bottom element 10 is made of metal such as a light
metal or alloy, e.g. aluminum or aluminum alloy, steel, brass or
the like material capable of being processed by punching, pressing
deep-drawing and the like shap1ng methods for mass production pur-
poses. The metal bottom element 10 is embedded or anchored ln a
rotationally symmetrical plastics sleeve element 12 having a duct
or passage 128 for connecting the interior or charge-bearing por-
tion 141 of cartridge case 14 with chamber 100 of the metal bottom
insert 10 so that actuation of a detonator cap in chamber 100 will
cause ignition of a charge provided in case 14.
Sleeve 12 is of a plastics material, preferably a
thermoplastic polymer composition which possesses a ball-pressure
hardness (60 inch-ball), at ambient (15-30QC) temperature, of at
least about 500 kp/cm2 and a modulus of elasticity of at least ab-
out 5 x 10 3 kp/cm2. Non-limiting examples of suitable thermoplast
ic materials include polyolefins such as polyethylene (high dens-
lty type), polypropylene and the like, polyamides, polyacetals,
polyesters, etc. In general, plastics of the type known to be su1t-
lO9Z440
able for manufacture of the cartridge case and including convent-
ional additions such as pigments, dyes, fillers, stabilizers and
the like can be used for the sleeve element of the inventive bot-
tom insert. Duroplastics, i.e. cross-linked or thermoset polymers
such as epoxy resins and the like may be used for the sleeve ele-
ment, e.g. by casting or molding a duroplastically setting compos-
ition to form the sleeve element around the metal bottom element
so as to form the composite unit. Sleeve elements of thermoplast-
ic polymer compositions can be produced and shaped by conventional
thermoplastics processing methods including injection moulding,
compression moulding or other shaping processes with simultaneous
anchoring of the metal element, e.g. by providing the latter in
the sleeve-producing mold prior to introduction of the plastics
material. In general, anchoring of the metal element in the plast-
ics sleeve will be obtained by providing projections or grooves
on the outer wall of cyllnder 104 and/or by flange 102. Preferably
the laterally projecting portion of flange 102 constitutes the
main anchoring component of the metal element but the lower face
of flange 102 may be rounded as indicated in broken line 103. How-
ever, anchoring projections that have an analogous effect may be
formed by continuous or interrupted beadings, ribs, webs or length
of thread in the outer wall of cylinder 104. Alternatlvely, a firm
connection between metal element 10 and plastics sleeve 12 can be
obtained by screwing in, that is, by suitably threaded elements
and without a plastic deformation of the sleeve material.
1~92440
The general shape of sleeve element 12 as illustrat-
ed in Fig. 1 is preferred but not critical as long as a sufficlent-
ly firm anchorage of metal element 10, on the one hand, and an ad-
equate connection between the sleeve and the cartridge case 14,
on the other hand, are ensured. Base portion 121 of sleeve 12 has
a generally cylindrical shape, bears against the upper surface 105
of flange 101 and has a smaller outer diameter than flange 101 so
as to accord with the desired depth of the extractor groove. Slee-
ve base 121 widens conically upwards and outwards to form abutment
126 against which the cartridge case 14 bears. A number of bead-
~ings 124 is provided at the outer sleeve wall for securing the
composite insert in the wall of case 14.
The inventive composite bottom insert consisting of
plastics sleeve 12 and metal element 10 firmly anchored therein is
used to close the lower end of case 14 in the same manner as prior
art all-metal bottom insert pieces. However, with the cbmposite in-
sert according to the invention, a comparatively non-problematic
plastics-plastics connection is obtained between the plastics car-
tridge case and the plastics sleeve of the insert. It is surprising
indeed that a major portion of the bottom insert of ammunition car-
*ridges can be made of a plastics material without any disadvant-
age in regard to the suitability of such cartridge for use as blan
or live ammunition even though the explosion pressure occurring up
on firing of the charge acts upon the plastics sleeve of the in-
sert rather than the metal bottom. As to the thickness of the pla-
stics sleeve material above the metal bottom element, it is suff-
lO9Z'~40
icient, in general, if the axial depth of aperture 128 and of thesurrounding transition portion 123 is at least about as large as
the axial depth of metal element 10.
Fig. 2 shows a modification, preferred from its
manufacturing aspects, of the metal constituent of the novel com-
posite insert. This metal element is made from a circular disc of
metal sheet, capable of being deep-drawn, for example steel, alum-
inum or brass, generally having the external dimensions and thick-
ness of bottom plate 27. For producing the metal element shown in
Fig. 2, the disc is punched or deep-drawn to form chamber 21 with
an axial depth greater than-that of the final chamber and then up-
setting the chamber portion to the desired axial depth while sim-
ultaneously forming the external annular beading 23. Aperture 28
in upper wall portion 24 may already be present in the disc or may
be formed during upsetting or later. Plastics sleeve 22 representec
in a semi-diagrammatical manner for connection with plastics case
29 can be produced and shaped as explained in connection with Fig.
1, or have a somewhat simplified structure as sho~m in Fig. 2. The
axial depth of abutment 226 is increased in a preferred embodiment
so as to obtain an enlarged surface of direct contact between the
plastics material of sleeve element 22 and the wall of the cartrid-
ge chamber of a weapon.
~ modified embodiment of the inventive cartridge bot-
tom insert is illustrated in Fig. 3 showing the lower part of pla-
stics sleeve 32 only as well as the bottom portion of a plastics
lO9Z440
cartridge case 34. The structure of the outer wall portion of
sleeve 32 and the correspondingly intermeshing part of the inner
wall of case 34 can be made in the manner illustrated in Fig. 1
and 2, or by any other means suitable for mutual connection. As
oth sleeve 32 and case 34 are made of a plastics material, varl-
us bonding methods for such connection will be apparent to the
xpert.
Metal element 30 is made in a manner similar to that
xplalned in connection with Fig. 2. An upwardly bent external rlm
36 is provided having an end face 361 for interaction with the
artridge extractor and ejector mechanism of a weapon. Metal ele-
ment 30 is anchored in plastics sleeve 32 in the manner explalned
above. The embodiment of the bottom insert shown in Fig. 3 is
especially suitable for gun ammunition cartridges and provides for
the use of relatively thin metal sheet materials without detractin
from the strength of rim 36 required for ejection of the cartridge
case after firing from a weapon.
- Fig. 4a shows a longitudinal sectional view of the
cartridge case for an improved blank ammunition cartridge made ess
entially of a plastics material only. Preferably, the bottom lnser
not shown in Fig. 4a is made as explained in connection with Flg.
1 and 2 but advantages will be achieved even if a prior art all-
metal insert is used.
Fig. 4b shows a cross-sectional view of the cartrldg
case illustrated in Fig. 4a. Cartridge case 41 has an upper end
109Z4~0
piece 42 shaped as an imitation projectile and is made of plastics
material throughout. The top of end piece 42 is furnished with a
notch 43 at which the wall of the casing can rupture when a charge
(not shown) contained in the chamber 45 is detonated. Preferably,
length XL of projectile-shaped end piece 43 is at most 25 % of the
total length HL of the cartridge case, because this provides for
savings in material and space and decreases the danger of an in-
tentional or accidental weakening of case 41 in the transition or
neck portion 47. Preferably, the inner wall surface of plastics
cartridge case 41 is furnished with a number of ribs or webs 46
extending axially or helically in a continuous or interrupted man-
ner over at least a part of the case wall. The volume of the inter-
nal charge-receiving space 45 of the case as well as the charge ca
be controlled in this manner, i.e. adaption to the intended charge
volume and improved uniformity of charge distribution. In addition,
ribs 46 may serve to prevent agglomeration of a charge consisting
of particulate explosives. The outer waLl of case 41 may be furnish _
ed with a number of troughs or grooves 46 for facilitating extract-
ion of the case from the cartridge chamber of the weapon. Struct-
uring of the cartridge case wall 41 as shown in Fig. 4b offers add-
ltional advantages in regard to manufacture of the cartridge case
by injection moulding of thermoplastics as a uniform filling of the
injection mould is facilitated by the internally and/or externally
situated ribs and grooves, respectively.
109Z440
In the manufacture of cartridges for live ammunitlon
of the type having a case made of plastics problems can arise due
to inadequate or excessive strength of the connection between the
case and the projectile. These problems can be resolved according
to an embodiment of the present invention illustrated in Fig. Sa
representing a longitudinal sectional view of the top portion of
a projectlle-bearlng ammunltion cartridge positioned in the cart-
rldge chamber of a weapon.
A bond control layer 55 is provided at the interface
between projectile 51 and neck 53 of cartridge case 57, preferably
on the projectile surface. For metal projectiles, layer 55 is made
of a bond improving agent, i.e. a compositlon capable of lncreas-
ing adhesion between a metaI surface (projectile) and a plastics
aurface (cartridge case) such as, for example, polymers of the type
used for interbonding the metal and plastics constituents of metal-
coated plastics laminates. Such polymers include polar groups and
can be selectèd, or example, from the class of copolymers made of
olefins and of unsaturated organic acids, unsaturated acid esters
or salts of unsaturated organic acids (lonomers).
- When using projectiles made of plastics, on the other
hand, the bond control layer will be of the type that decreases
plastlcs/plastics adhesion or interwelding so that the plastics
projectile will not be bonded too strongly to the plastics cartrid e
wall, e.g. when producing the plastics cartridge by injection mold-
ing wlth the projectile lnserted into the mould.
- 15 -
109Z440
According to a preferred modification, cartridge
case 57 is provided with shoulder elements 56 formed as an integral
part of the plast~cs cartridge case so that projectile 51 can be
pushed into neck 53 of a preformed case 57 until the lower end of
the projectile projects into the internal space 52 of case 57 and
bears against the shoulder elements 56.
Fig. 5b further illustrates the arrangement of the
shoulder elements in a cross-sectional view of the cartridge case
of Fig. 5a.
According to another preferred embodiment of the
projectile-bearing type ammunition cartridge having a projectile
made of plastics the lower portion 512 of projectile 51 that pen-
etrates into neck 53 and case 57 has a larger cross-sectional dia-
meter than the upper portion 511 of projectile 51 that protrudes
from the case, i.e. extends upward beyond edge 58 of neck 53. This
embodiment assures that the ammunition cartridge can be inserted
into the ammunition chamber of the weapon and easily removed there-
from even if not fired while, at the same time, providing for opt-
imum projectile guidance in the barrel of the weapon upon firing.
It is to be noted that the terms "plastics casing",
"plastics projectile" and "made of plastics" are not intended as a
restriction to such objects as consist entirely of a plastics mat-
erial. In fact, the cartridge case or case wall of any embodiment
of the cartridge according to this invention may include a reinforc
ing inlay or layer of fibres such as glass fibres or of sheets or
109~:4~0
foils including reinforcing metal layers of the type known for re-
inforcing plastics objects. Cartridge cases consisting essentially
of plastics compositions that may, or may not include particulate
or fibrous fillers are generally preferred, however, for reasons
of economy. Cartridge cases consisting of thermoplastic polymer
compositions can be shaped by blowmoulding techniques, or may poss-
ess a molecular orientation that provides for a more or less pro-
nounced reinforcing effect.
While the embodiments explained in connection with
Flg. 4a, 4b and 5a, 5b are preferably used with composite inserts
of the type explained in connection with Fig. 1-3, prior art all-
metal inserts could be used if desired.
The essential advantages of the novel composite car-
tridge bottom insert according to the invention can be realized in
combination with any ammunition cartridge that has a plastics case,
notably for use in blank or live rifle ammunition. In addition to
reduced costs of materials and production, the novel insert prov-
ides for functional improvements believed to be due to the fact
that the metal/plastics connection is situated within the bottom
insert rather than between the bottom insert and the cartridge cas~ .
Furthermore, the novel composite bottom insert requires comparati-
vely less metal per cartridge and can be manufactured at less cost~
per unit.
Preferably, the novel bottom insert according to the
invention is formed first by shapingly deforming, e.g. deep-draw-
lO9Z~O
ing, of a metal sheet material, e.g. aluminum, aluminum alloy,steel, brass or the like, having a gauge substantially equal to
that of the lower base portion of the metal bottom element, e.g.
typically in the order of 1 mm (+ 0.3 mm) for rifle ammunition
cartridges and, secondly, by anchoringly securing the metal ele-
ment in the plastics sleeve element which may be preformed or,
preferably, is formed of a suitable thermoplastics composition ar-
ound the upper or anchoring portion of the metal element. Subse-
quently, a conventional detonator cap can be pressed into the cap-
receiving and cap-holding chamber provided in the metal bottom
element. Then, the completed assembly of cartridge bottom insert
plus detonator cap is introduced into the lower end of a plastics
cartridge case that may have a conventional structure or be design-
ed in accordance with one of the preferred cartridge case embodi-
ments disclosed herein. In general, a suitable charge will be pro-
vided within the case prior to closing its lower end with the
cartridge bottom. ~lternatively, the charge can-be introduced via
the top end of the cartridge case.
According to a preferred specific embodiment of the
inventive manufacturing method, the metal sheet for producing the
etal bottom element is provided in the form of a disc that may,
or may not, have a central aperture, and deforming such disc in a
unch-dye or the like for shapingly deforming the metal disc and
roducing a generally tubular cylindrical protrusion which, in a
- 18 -
__
~092~0
subsequent shaping step is pressingly deformed so as to form a
flanged or rimmed upper portion 23 as depicted in Fig. 2. Aperture
28 may be formed in connection with this second step unless the
disc-shaped blank used had such an aperture to start with, or pro-
duced subsequently.
Thus, it is apparent that the invention satisfles
the objects, aims and advantages set forth above and provides for
substantial improvements in connection with ammunition cartridges,
notably for use in rifles. While the invention has been described
in conjunction with specific embodiments, it is evident that many
alternatives, modifications and variations will be apparent to tho-
se skilled in the art in the light of the foregoing description.
Accordingly, it i~ intended to embrace all such alternatives, mod-
ifications and variations that fall within the spirit and broad
scope of the appended claims.
B cconDI~lcLY
