SMALL-CALIBRE SHELL

Abstract: The present invention relates to a new type of small-calibre shell with a certain armour-piercing capacity. The shell is of the basic type which is known per se which comprises an elongate, preferably solid shell core or penetrator (2) made of hard metal, heavy metal or equivalent which is axially centred inside a hollow metal casing (1) defining the outer shape of the shell with its front conical tip and rear end. Characteristic of the invention is the manner in which the penetrator (2) has been centred and fixed inside the shell casing (1). This has in fact been done on the one hand, in the front part of the shell, directly between the penetrator (2) and the inside of the shell casing (1), and on the other hand, in the rear part of the shell, with a specially designed support part (3) as an intermediate part. Finally, the various parts have been fixed relative to one another by means of a ballast material (4) which is arranged in the rearmost part of the shell and which must satisfy certain special requirements in order to guarantee gastightness there relative to the inside of the shell casing (1). The great advantage of the shell according to the invention is the good precision of the shells produced in accordance with it and also that the ballistic data of these shells can easily be adapted to other standard ammunition of different calibres.

Description: Small-calibre shell The present invention relates to a new improved small-calibre shell with a certain armour-piercing capacity. The shell according to the invention is of the basic type which includes an outer casing made of a thinner metal material such as tombac, tombac-plated sheet steel or the like, which defines the outer shape of the shell, and a shell core enclosed therein made of extremely hard armour-piercing material such as hard metal, heavy metal or equivalent. Even though the designation small-calibre can be somewhat vague, it is weapon calibres under 20 mm which are concerned here and then chiefly calibres up to and including 50 calibre which are now of course also found in modern handheld firearms chiefly intended for sniping at extremely long ranges. In the case of weapon calibres of 20 mm and above, it would probably be more efficient to use so-called dart shells or other more expensive and more effective shell types for combating armoured targets than the simpler and cheaper type of which the present invention is an example. Previously known so-called armour-piercing small- calibre shells have very generally consisted of an outer casing made of a relatively thin sheet material which in most cases consisted of tombac, tombac-plated sheet steel or equivalent and a core enclosed therein made of an extremely hard material which often consisted of hard metal which is actually not a metal or metal alloy of course but rather various types of metal carbides and then chiefly tungsten carbides, or heavy metal which in most cases is tungsten alloys. As a rule, the armour-piercing core in previous types of armour-piercing small-calibre shells was shorter than and sometimes also of smaller calibre than the inside of the casing. The shells therefore as a rule also contained various types of filling material in order to fill out the interior of the casing and hold the armour- piercing core in place until the shell reached its target . The armour-piercing capacity of the armour- piercing small-calibre shells is of course clearly limited but, as the use of anti-splmter armours has increased to a very great extent in recent years and as the armour-piercing small-calibre ammunition can under favourable circumstances deal with targets of this type, the need for this type of ammunition can be expected to continue to increase. Clearly the greatest problem with the current generation of armour-piercing small-calbire ammunition, however, is that, quite generally, it has such great differences as far as the ballistic characteristics of the shells it includes, compared with corresponding standard ammunition of the same calibre, that precision shooting with mixed ammunition or rapid changing between different ammunition types is made considerably more difficult. The aim of the present invention is to offer a new type of small-calibre shell with a certain very good - with regard to its own calibre - armour-piercing effect and, probably its greatest advantage, with such an inner construction that its ballistic data can easily be adapted so as to be very close to or even be made completely identical with the majority of standard ammunition types with the calibre range concerned Shells designed in accordance with the invention moreover have such good and uniform precision that they fall into the same class as the so-called sniper or special ammunition for marksmen. To sum up, the present invention thus relates to a small-calibre shell with a certain armour-piercing capacity of the type which comprises an elongate, preferably solid shell core or penetrator which is axially centred inside a hollow shell casing and which has a cylindrical main part and a tip which tapers conically forwards m the intended flight direction of the shell in one or more stages The tip of the shell core itself can thus have the shape of one or more successive frustoconical parts of ever greater apex angles and a concluding conical part, or alternatively a single conical tip. The outer shape of the shell on the other hand is defined entirely by the shell casing -and this is therefore designed from the outset with the conical tip which is appropriate for each specific shell type. The invention iε characterized in the first place in that the shell cores or penetrators are centred around the longitudinal axis of the shell casing, that is to say of the future finished shell, between a first accurate bearing or support against the inside of the shell casing in the front conically pointed part of the shell and a second bearing in the rear part of the shell by means of a support part or insert which is arranged inside the casing and contains at least the very rearmost part of the shell core and which in turn is held in place in the casing by a ballast material which completely fills the rearmost part of the casing. The bearing between the inside of the shell core and the front part of the penetrator takes place either along one of the frustoconical parts of the shell core tip or along the transition or interruption edge between two parts which may be constituted by the cylindrical part of the shell core and its single-coned tip or alternatively by different parts of the coned tip. The edge(s) which in this connection form(s) the transition between the tip and the cylindrical part or alternatively between different parts of the tip coned in a number of stages is then a natural circumferential bearing line for centring the front part of the penetrator against the inside of the casing well into the part of the same which forms the tip of the shell, providing of course that the penetrator has a smaller diameter than the inside of the shell casing and also a more obtuse apex angle on its own tip than the inner apex angle of the casing. The possibility of locating the bearing of the shell core against the inside of the casing along an entire frustoconical surface is selected in particular when there is a need for the greater friction contact _ . surface, which is then obtained, m order to ensure that the shell core does not have a tendency to remain still inside the rotationally stabilized casing, that is to say in ammunition types with extremely high speed of rotation. With this variant, the possibility exists of increasing the contact surface between the shell core and the inside of the shell casing to correspond in principle to more than half the tip length of the shell core. The advantages with the four-part Dasic construction indicated above are numerous. Firstly, the armour-piercing shell core is very well supported and centred m the shell casing right up to the moment that the shell reaches the target. Secondly, the ballistic data of the shell can easily be modified by adjusting the ratio between the weight of the ballast material and of the support part respectively, which can be done both by varying the material selected in the different parts and by varying their mutual volume ratios. At the same time, the same armour-piercing shell core can be used in a number of different adjacent calibres, of which there are of course a large number intended mainly for lighter handheld firearms and this will of course mean considerable cost savings. As far as the support part or insert is concerned, this can be made of any material with sufficiently good strength and mouldability Steel or aluminium, for example, is a good material but the possibility of using certain plastics for this purpose is not inconceivable. As far as the ballast material filling the rearmost part of the casing is concerned, this is required to be plastically deformable so that it can be given the desired final shape at the same time as allowing the rearmost part of the shell to be finally shaped in a manner known per se including folding-in at the rear of the rear outer edge of the casing at the same time as possibly equipping with a so-called boat tail end by upsetting In this connection, it may be appropriate to point out that it is very important that an absolutely gastight connection is obtained between the inside of the casing and the ballast material. Excellent materials for - this purpose are lead and various lead alloys. It also applies for the shell according to the invention that the armour-piercing core or penetrator can advantageously be given the shape of an elongate cylinder which also has, in addition to the tip which tapers conically in one or more stages, a frustoconical rear end. This frustoconical end provides an excellent support for the part of the penetrator which the support part or insert overlaps, that is to say the part of the penetrator which is inserted into the insert. As the contact line between the penetrator and the inside of the casing is to lie in the part of the casing which forms the tip of the finished shell and the penetrator must therefore have a diameter which is at least slightly smaller than the maximum internal dimension of the casing, there will be m many shell calibres an accessible space between the inside of the shell casing and the penetrator which allows the support part or insert to continue at least some way along the cylindrical part of the penetrator As the shell casing as a rule has a softer shape than the shell core, a thin tubular first empty space is formed immediately in front of the support part and a second empty space is formed at the very front inside the shell tip. The invention has been defined m the following patent claims and it will now be described in somewhat greater detail with reference to attached Figures 1 and 2 which show two different partly cut-away longitudinal projections of shells made m accordance with the invention. The two figures show shells with slightly different outer shape but the major difference resides in the fact that the shell cores included in the respective shells are of different types The shell according to Fig 1 has a shell core with a single-coned tip while the shell according to Fig. 2 has a tip coned in a number of stages. The shell shown in Fig 1 consists of an outer shell casing 1 made of, for example, tombac or tombac- plated sheet steel, and the inner shell core or penetrator 2 which is made of hard metal, heavy metal or another equivalent material . Also included is a support part or insert 3 which can, for example, be made of aluminium, steel or another suitable material. Finally, the ballast material, designated 4, is included, which fills the rearmost part of the shell casing and in the example shown consists of a lead alloy containing 1-10% antimony. As can be seen from the figure, it is the shell casing 1 which defines the outer shape of the shell while the shell core or penetrator 2 has a considerably simpler shape with a single conical tip 5, an elongate cylindrical main part 6 and a short frustoconical rear part 7. The peripheral edge line 8 which forms the transition between the conical tip 5 of the penetrator and its cylindrical part 6 also forms, as can be seen from the figure, the bearing edge against the front pointed inside of the casing which gives the penetrator its front support. As far as the support part or insert 3 is concerned, it is mainly that part of the same, with reference number 9, overlapping the frustoconical rear part 7 of the penetrator, which is responsible for the rear support of the penetrator 2, even though the support part 3, as can be seen from the figure, extends with its neck part 10 forward along the cylindrical part 6 of the penetrator, which is allowed by the clearance between the latter and the inside of the casing 1. As can be seen from the figure, the rear part of the shell casing is upset in to form a so-called boat tail 11 and at the same time as this, which is carried out as a final operation, the rear edge 12 of the casing has also been upset in towards the rear plane 13 of the shell. By then working the lead ballast material plastically to its final shape, a good gastight seal is obtained between the ballast material and the inside of the shell. Quite generally, the shell is otherwise manufactured in such a manner that the shell casing 1 in its front pointed part is preformed to on the whole final dimensions while its rear part is only preformed and subsequently the finished penetrator 2 and the support part 3 are guided into place followed by the only preformed ballast part 4, whereupon the middle and rear parts of the shell are given their final shape and dimensions. The shell shown m Fig. 2 is produced m a manner corresponding to that in Fig. 1 and in principle from the same materials. In this case, hcwever, the casing 14 has a somewhat different shape but above all the shell core 15 is made with a double-coned tip, the first part of which consists of a frustoconical part 16 with a given first apex angle α and the second part 17 of which consists of a completely conical part with a substantially greater apex angle σ . The shell tip thus has a double-interrupted side edge line Other tip constructions, which include a number of frustoconical parts following one another with successively greater apex angles, also fall within the same basic construction of course. Also included in the shell illustrated in Fig. 2 is the support part 18 which has the same basic construction as the support part 3 in Fig. 1 Also included is a ballast part 19 consisting of lead alloyed with antimony. The end of the shell has been formed with a pronounced boat tail 20 in the same manner as the corresponding detail m Figure 1. As can clearly be seen from Fig. 2, the contact between the front part of the shell core 15 and the inside of the shell casing 14 is transferred completely to the frustoconical part 16 of the former. As was pointed out earlier, this represents a construction alternative because the friction surface between the tip part 16 of the shell core and the inside of the shell casing becomes so great that it is possible to transfer great frictional forces between these two shell parts As in the alternative according to Fig. 1, two empty spaces 21 and 22 are formed inside the shell casing which are not filled by the shell core 15, the support part 18 or the ballast part 19 By virtue of the fact that the shell core is so well supported inside the shell casing, however, this does not represent a disadvantage but rather an advantage which increases the possibilities of adapting the shell according to the invention to the ballistic data concerned in each individual case. The shell according to the invention therefore comprises the six different components, the shell casing, the shell core, the support part, the ballast material and also the first and second empty spaces, the differing size, shape and axial displacement of which can be varied in order to impart the desired ballistic data to the finished shell. To a certain extent, the selection of material in the different parts, with the exception, of course, of the empty spaces, can also be varied within the limits applying for the function of the various parts.

Claims: Patent Claims 1. Small-calibre shell with a certain armour- piercing capacity and - extremely high precision, of the general type, which comprises an elongate, preferably solid shell core or penetrator (2) made of hard metal, heavy metal or another extremely hard and heavy material which is axially centred inside a hollow metal casing (1) defining the outer shape of the shell with its front conical tip and rear end, characterized in that the shell core or penetrator (2) is centred around the longitudinal axis of the future finished shell between an accurate first bearing or support (8) against the inside of the shell casing (1) in the front continuously conically pointed part of the shell and a second bearing in the rear part of the shell by means of a support part or insert (3) which is arranged inside the shell casing (1) and contains at least the very rearmost part (7) of the shell core and which in turn is held in place inside the shell casing (1) by a ballast material (4) which completely fills the rearmost part of the latter. 2. Small-calibre shell according to Claim 1, characterized in that the shell core or penetrator (2) has the shape of a cylindrical bar (6) with a conical front tip (5) , the front bearing of the shell core (2) against the inside of the shell casing taking place along the edge transition (8) between the cylinder shape (6) and the conical tip (5) . 3. Small-calibre shell according to Claim 1, characterized in that the shell core or penetrator (15) has the shape of, in its main part, a cylindrically shaped bar, provided with a tip which tapers forwards in at least two stages in the envisaged direction of flight of the shell, each stage having a frustoconical shape with the exception of the last stage which has a completely conical form, and the different stages having apex angles (α, σ) which increase in the direction of flight. 4. Small-calibre shell according to Claim 1, 2 or 3 , - - characterized in that the end of the penetrator (2) has the shape of a truncated cone (7) and the support part or insert (3) overlaps at least this conical end part (7) . 5. Small-calibre shell according to one of Claims 1- 4, characterized in that the shell core or penetrator (2) has a smaller calibre than the greatest internal diameter of the shell casing (1) and in that the support part or insert (3) containing the rearmost part (7) of the shell core (2) , as far as it extends, completely fills the space between the rear part of the shell core and the inside of the shell casing. 6. Small-calibre shell according to one of Claims 1- 5, characterized in that the part of the support part or insert (3) , which contains or overlaps the shell core or the penetrator (2) , extends as far forward along the latter (2) as the shape of the shell and the actual material thickness there of the support part or insert (3) allow, while an empty space is formed in front of this and forward to said first bearing (8, 16) . 7. Small-calibre shell according to one of Claims 1- 6, characterized in that the ballast material (4) completely filling the rearmost part (7) of the shell casing (1) is plastically deformable so that a good fit and gastightness against the inside of the casing end can be obtained when the latter is finally shaped in a known manner to form, for example, a so-called boat tail (11) . 8. Small-calibre shell according to one of Claims 1- 7, characterized in that the ballast material (4) consists of lead or a lead alloy.

Inventors: BORG GUNNAR, KARLSSON NILS-OLOF, BORG, GUNNAR, KARLSSON, NILS-OLOF
Applicants: BOFORS CARL GUSTAF AB, BORG GUNNAR, KARLSSON NILS OLOF, BORG, GUNNAR, KARLSSON, NILS-OLOF
Application year: 1997
Main classification: F42B12
IPC codes: F42B12