GB2038457A

GB2038457A - Practice ammunition braking device

Info

Publication number: GB2038457A
Application number: GB7944473A
Authority: GB
Original assignee: Dynamit Nobel AG
Current assignee: Dynamit Nobel AG
Priority date: 1978-12-30
Filing date: 1979-12-28
Publication date: 1980-07-23
Also published as: IT1164919B; FR2445510A1; IT7951228A0; NL7909364A

Abstract

A round of practice ammunition is given a range reduced with respect to the range of a corresponding live round by provision of a braking device (4) comprising two or more elongate braking fins (6) connected to the projectile body (1) of the round and extending longitudinally thereof when the round is in its pre-firing condition. The fins (6) are adapted to open out from the body of the projectile by centrifugal force on firing of the round, e.g. by providing a bending zone (9) of reduced thickness. If desired, the unopened fins may be held at least partly inside a separate cartridge case. <IMAGE>

Description

SPECIFICATION Practice ammunition round This invention relates to a round of practice ammunition, more especially, but not exclusively, a practice shell equipped with means for drift stabilisation and a braking device.

When designing practice ammunition rounds and also, for example, practice grenades and even, possibly, also practice rockets, it is desirable to reduce the maximum effective range by comparison with that of the live missile which is to be simulated, so as to be able to train safely in small firing areas. Hence practice ammunition, specifically practice shells and bullets made of synthetic plastics, and which is usually in the rifle calibre range, has been devised, of which the maximum firing distance amounts to only about 10% of that of the live ammunition. However, on account of their small shell mass, such practice shells necessitate changes being made to the breech of the weapon, or alternatively, necessitate the use of a supplementary appliance, in order to guarantee the automatic functioning of the weapon.

Furthermore, a practice shell having a shortened effective range and which is drift stabilised, is described in German Patent Specification No. 14 53 827, which makes possible automatic functioning of a weapon without any changes being made to the weapon or without use of supplementary devices. This practice shell, which is also known as a shorttrajectory shell, has an open-ended axial bore, which is open as the shell travels through a weapon barrel and allows discharge of propellent gases therethrough, in addition, this practice shell can be provided with a braking device on the wall of the bore. This device is constructed, for example, as a screwthread with a pitch extending opposite to the shell rifling. An additional braking effect can also be achieved if the practice shell is formed with a front end face which is perpendicular to the axis of the shell.Even by such means, however, the maximum effective range of this practice shell is as much as 50% of that of the corresponding live shell.

According to the present invention, there is provided a round of practice ammunition for firing from a weapon, the round providing a projectile of substantially the same external shape as a projectile provided by a corresponding round of live ammunition and having handling characteristics and containing substantially the same propellent charge as said corresponding round, the projectile being stabilised against drift and comprising a braking device comprising two or more elongate braking fins which are connected to the body of the projectile and extend longitudinally thereof when the round is in its prefiring condition, which fins are adapted to open out from the body of the projectile by centrifugal force on firing of the round.

A round of ammunition embodying this invention is fundamentally of simple construction and may be used in a weapon normally used for firing live rounds without any modification of the weapon involved and will generally have the maximum effective range reduced by more than 50% as compared with that of the live shell.

Practice rounds according to this invention may be designed for use in medium and large calibre weapons, and more specifically in hand weapons, i.e. firearms, automatic weapons, machine guns or automatic cannon.

With a round embodying this invention, the braking fins are arranged symmetrically distributed over its circumference and extend longitudinally of the axis of the projectile in the initial position, i.e. prior to firing and during the passage through the barrel of the weapon, and are only opened out after leaving the muzzle because of the centrifugal force caused by the rotation of the projectile and, consequently, are so changed in their shape that the desired braking action is established. The size of the braking effect depends on the number of braking fins, their shape, surface and strength, and accordingly the braking arrangement can be designed to ensure that the desired reduction in practice projectile range is obtained.In this respect, the braking fins considered in the direction of travel through a weapon barrel - are preferably connected at their forward end to the body of the practice projectile, so that they are swung out into the direction of flight after the practice projectile has left the weapon barrel. The weight of the practice projectile will usually be equal to or only slightly smaller, preferably by not more than 20%, than that of the projectile which is to be simulated, so that the full functioning of the weapon is guaranteed without any modifications thereto, or use of additional devices.Although the braking arrangement of the projectile of a round embodying this invention is of very simple design and operates exclusively in accordance with the centrifugal force system, it enables the required very considerable reduction in the maximum trajectory to be achieved. In turn, this means that a correspondingly small dangerous zone exists in the direction of the barrel, so that these projectiles can be used in small-size training areas.

In a preferred development of the invention, provision is made for the braking fins to comprise a portion of reduced rigidity extending thereacross in a region at which the fins are subjected on firing of the round to the bending effect of the centrifugal force to which the projectile is subject.

In this way, opening out of the fins is controlled and it is possible to establish when the braking device controlled by the centrifugal force becomes operative, in accordance with the desired influencing of the trajectory of the projectile. By way of example, the braking fins may for this purpose be provided in angled zones thereof adjacent positions at which they are connected to the projectile body with a reduced thickness of material, i.e. with a smaller cross-section.

However, it is also possible for the material of the fins to be of equal thickness throughout, but of softer material in these angled zones, because of an appropriate local heat treatment.

In a particularly useful form of round embodying this invention, the braking fins are formed integrally with a common central holding member, the holding member being held on the body of the projectile in a particularly simple manner. The braking arrangement may then be held on the projectile especially in the region of its forward end, for example, by being clamped between the projectile body and a nose member thereof. One particularly convenient way of making this shaped component is by stamping from sheet metal and then deforming it into a three-dimensional configuration, preferably by deep-drawing. Moreover, the body of the projectile is prefeably formed with one or more recesses in which the braking fins are fitted in :such matter that they are not proud with respect to the projectile body when the projectile is in its pre-firing condition.This arrangement ensures that any impermissible bending of the braking fins at the time of handling or transport of the projectile, etc., is largely avoided. With a round comprising a separate cartridge case as against housing propellent and ignition system in the projectile body and in which the fins are connected to the projectile body at their forward ends, it is additionally possible to make provision For the neck of the cartridge case to engage over the rear openable end of the braking fins and, as a result, to fix them reliably in their position against the projectile body until the time of firing. Finally, it should be noted that a braking arrangement of the aforesaid type can be used in combination with other features hitherto employed in the shorttrajectory shell, if an even greater reduction of the effective range of the Dractice projectile should be required.

It is also possible for the braking fins to be disposed on the rearward end and projecting rearwardly beyond the projectile body in their prefiring condition. Such an arrangement is particularly convenient when a separately formed cartridge casing containing case can fit over the braking fins in the pre-firing condition and hold them parallel to the axis of the projectile body.

Instead of the braking fins bearing as indicated previously herein, against the projectile body in their pre-firing condition, the braking fins in this case lie adjacent the wall surface of the cartridge casing weapon barrel; they preferably lie flush with the wall surface of the cartridge casing i.e.

without any shoulder or bend formation, rearwardly beyond the tail or base of the projectile body.

It has proved particularly advantageous in such a case to construct the braking device as a sleevelike extension on the projectile body. The sleeve like extension is formed with incisions or interstices of suitable width which define therebetween braking fins and extends rearward of the projectile body. With this extension, it is very readily possible to produce the braking fins in the suitable shape, length, breadth, thickness, etc., according to the braking action required in the individual case, especially if the sleeve-like extension is formed integrally with the projectile body.

The production of the projectile body with braking fins integrally provided on the base thereof can be effected by a shaping operation with or without removal of swarf. Projectile bodies are preferably produced by deep-drawing with sleevelike extension thereon, the braking fins being formed from the sleeve-like extension for example by subsequent stamping. Depending on the shape of the projectile body and the material, of its construction, it is however also possible to produce the projectile body by extrusion or casting.

Manufacture of a round in which the fins are disposed on the rear end of the projectile body can be simplified if the sleeve-like extension is formed as a separate shaped part from the projectile body and is so connected to the projectile body as to remain in contact therewith during flight of the projectile. For example the sleeve-like extension may be formed from what is originally a flat circular disc, from which are stamped out the braking fins extending from the rim. The fins are then so bent over at their "inner" ends that, after connecting the shaped part to the base of the projectile body, they extend rearwardly therefrom. The fixing can, for example be carried out by use of screws or adhesive.However. the fixing is particularly simply and reliably achieved with a construction in which the sleeve-like extension is formed as a separate shaped part from the projectile body, the extension being so connected to the projectile body as to remain in contact therewith during flight of the projectile. It is then possible for the forward extension of the moulded part to enter the recess with a frictional and/or a form-looking connection therebetween achieved by the forward extension simply being forced with a press fit into the recess in the projectile body. The forward extension itself can be made solid or even hollow, for example, cupshaped.

The sleeve-like extension may, moreover, contain a relatively thin-walled lining member in intimate contact therewith the lining member being closed at the forward end at which it may be supported on the bottom of a forward extension if present on a separately formed sleeve-like extension. The lining cah for example be made of cardboard, polyvinyl chloride, polyethylene or metal foil, for example aluminium foil. The presence of the lining makes possible an increase in the efficiency of the propellant charge housed in the cartridge case in which the sleeve-like extension is fitted and as a result leads to an improved internal ballistic effect. Furthermore, it is possible with this lining, at the time or preparing practice ammunition, to mitigate the effect of impact, friction or compressive stresses on the propellant charge powder caused by the braking fins; this may be particularly de,sirable, if the propellent charge is of high sensitivity.

Target practice ammunition of all calibres can be modified with a braking arrangement embodying this invention to achieve a very greatly reduced safety range, while ensuring the fully automatic functioning of the weapon and not needing to effect any modification to the weapon or use additional devices therewith. Moreover, because of their very short effective range, practice projectiles of ammunition according to the invention mey be used, instead of the disintegrating ammunition used in the mediumcalibre range, which, in its turn, serves as a substitute for the blank ammunition which is not available in this calibre range for technical weaponry reasons.A particular advantage of medium-calibre projectiles of this invention not to be found with disintegrating ammunition is that the loading of the weapon is the same as with the live ammunition, in respect of both the breechloading system and the barrel-loading system.

Moreover ammunition embodying this invention and including braking fins disposed on the rear end of the projectile body is particularly suitable when of small calibre for simulating live ammunition of like calibre for example ammunition for rifles and revolvers since with this type of practice ammunition relatively long braking fins producing a particularly strong braking effect can be provided. Hence a particularly large reduction in firing range can be achieved, especially when the ammunition additionally includes further and known trajectory reducing measures.

For a better understanding of this invention, land to show how the same can be carried into effect, reference will be made by way of example onl to the accompanying drawings, wherein: Figure 1 shows, mainly in longitudinal section, a practice round embodying this invention, having a braking device in its initial position: Figures 2a and 2b show in longitudinal section and in plan view, the projectile of the practice round after firing:: Figures 3a and 3b show in plan view and in their open configuration different braking devices to that shown in Figures 1 to 2b; Figure 3c shows, in section, the braking device of Figure 3a; Figure 4 and 5a, show in longitudinal section, different forms of practice round embodying this invention; Figure 5b is a plan view of the round of Figure 5a; Figure 6a shows in elevation and longitudinal section a practice round embodying this invention having a cartridge case; and Figure 6b shows the round of Figure 6a in plan view, after the round has been fired.

Figures 7 and 8 show half in elevation and half in section practice rounds with braking fins of different length, Figures 9 and 10 are similar view to those of Figures 7 and 8 of practice rounds with an additional lining, Figure 11 shows half in elevation and half in section a practice round with a separate moulded braking fin, Figure 1 2a shows a practice round in longitudinal section, and having braking fins spread out and, Figure 1 2b shows the practice round of Figure 12a in underside plan view.

Referring to Figure 1, the practice round shown almost completely in longtudinal section comprises a shell body 1, having a surface recess 2 and a shell nose 3, which is shown in elevation.

Positively clamped between the shell body 1 and the shell nose 3 is a braking device 4 integral with a central common holding part 5. The braking device comprises four braking fins 6 (see Figure 2b) fitted into the recess 2, which is in the wall surface 8 of the shell body 1 and sufficiently deep that they do not extend laterally beyond the wall surface when in their initial position. A bending zone 9 of reduced thickness is formed between the fins 6 and the holding part 5.

The shell nose 3 can be made of aluminium and, as shown in the left half of Figure 1, can be connected to the shell body 1 by means of a screwthread 10. However, it may also be made as a hollow body 7 of synthetic plastics material and, as shown in the right-hand half of Figure 1 , be connected by means of a press-fitted connection 11 to the shell body 1. The practice round also comprises a driving band 12 and contains a tracer charge 13.

Figure 2a shows, in longitudinal section, the practice round of Figure 1 with a shell nose 3, which is screwed into position, the round having the braking devices in their post-firing disposition with the braking fins 6 opened out. Figure 2b shows a plan view from above of the round of Figure 1 , from which it is possible to see the four extended, symmetrically arranged braking fins 6 with their transversely-extending bending zones 9 Figures 3a and 3b show in plan view two different integrally-formed braking devicas 4 to that shown in Figure 2b, the devices including six and eight braking fins 6, respectively, joined to a central holding part 5 and incorporating transversely extending bending zones 9 of reduced thickness. These shaped parts are preferably made as stamped parts.The starting material used in their production may be a deep-drawn sheet metal consisting, for example of steel, brass, copper, aluminium or their alloys, and subjected to suitable surface treatments, for example, with chromate or cadmium. In Figure 3 c, the stamped part of Figure 3a, shaped by deep-drawing, is shown in transverse cross-section. It shows the central annular holding part 5 and the braking fins 6 with their bending zones 9.

The practice round, which is shown in longitudinal section in Figure 4, in which like reference numerals represent like parts in Figure 1, has a braking device 4 combined with a short trajectory shell of conventional type comprising an open-ended axial bore 14 and a hood-like shell nose 1 5 of synthetic plastics material, which may merely be "dropped" in the weapon barrel onto the forward perpendicular end face 1 6 of the shell.

Provided that it permits the feeding of the ammunition into a weapon, the practice round shown in Figure 5a, in which like reference numerals again denote like parts in Figure 1, may also be provided initially with a blunt head piece 17, which clamps the braking device 4 in the shell body 1. The plan view of this practice round as represented in Figure 5b, shows several recesses 18 in the wall surface 8, rather than the single recess or indentation 2 of Figure 1, which recesses are each intended for the fitting of a braking fin 6.

This combination of braking device, according to the invention and the blunt forward end face, enables a maximum increase in resistance to be obtained and, as a result, a particularly effective shortening of the effective firing range.

Figure 6a also shows a practice round for handweapons, half of this figure being in elevation and half in section. Here also, the braking device 4 is clamped between the shell body 1 and the shell nose 3. A cartridge case 19 engages with its forward end 20 over the rearward end of the braking fins 6 and accordingly secures these in their initial position, i.e. in their bearing position against the shell body 1. Figure 6b is a plan view of the practice round after firing has occurred, showing four extended braking fins 6.

The practice round which is shown in halfsection in Figure 7 and which is a drift-stabilised practice shell whose shell body 1 is made, for example, of copper, brass or aluminium, comprises at the rearward end 21 of the shell body a sleeveshaped extension 22 which is formed integrally with the shell body 1 and provides braking fins 6 as a result of longitudinal slots 22 extending from the free end of the extension 22. In their pre-firing condition, as shown, the braking fins 6 are aligned with an exterior wall surface 8 of the practice shell which is at this stage provided by a cartridge case 1 9 against whose inner surface they lie. The braking fins 6 extend into the cartridge case 1 9 to somewhat more than half the length thereof.The shell body is preferably formed with the extension 22 by deep drawing and slots 23 are then formed for example by stamping or milling in the extension 22. On account of the cavity formed by the sleeve-like extension 22, a larger amount of propellent charge powder 24 can be arranged in the cartridge case 1 9 as compared to a corresponding live ammunition shell, thereby compensating, in effect, for the influence of a reduced shell mass. At the forward ends of the braking fins 6, i.e. at their transition into the unslotted part of the extrusion 22, indentations or notches 25 extend in the circumferential direction around the exterior of the extension 22, so as to facilitate the bending over of the braking fins in this zone under the action of centrifugal force when the shell is in flight.

Figure 8 shows, also in half-section, a practice round which is in principle of the same design as that shown in Figure 7 but which, however, differs from that shown in Figure 7 that the braking fins 6 extend as far as the base 26 of the cartridge case 19, thereby to increase the braking effect achieved after the spreading or opening operation has occured. In this case, the fins 6 are not shown as having any notches or indentations in their bending zone, i.e. at the forward end.

The practice round shown in Figure 9 additionally comprises a thin-walled cup shaped lining 27 of synthetic plastics material, which is supported with its forward closed end 28 on the bottom surface 29 of the shell body 1 of a practice round. In order to fill that space in the cartridge case 7 which is not occupied by the braking fins 6, the lining 27 is provided at its rearward end with an externally thickened zone 30. Figure 10 shows a practice round which is similar to that shown in Figure 8, but which contains a lining 31 which is similar to the lining 27 in Figure 9 but extends as the base of the cartridge case 19 in a uniform thickness because of braking fins 6 also extending to the base 26.

Figure 11 shows a practice round, with which the braking device is constructed as a separately moulded part 32, which is connected to the rear end 21 of the said shell body 1 by a frictional fit.

The part 32, which can be made of the same material as the shell body 1, but may also be made of another material, comprises a forward cupshaped extension 33, with which it is held by a press fit in a recess 34 of the shell body 1 of the practice round. The extension 33 could also be solid. Rearwardly, the extension 33 merges into braking fins 6 formed with slots 23 therebetween, which fins, again bearing flush internally against the cartridge case 19, merge smoothly, i.e.

without any shoulder, into the wall surface 8 of the practice round provided by a cartridge case 19.

Finally Figure 1 2a shows a shell body of the type shown in the practice round of Figure 7 with braking fins 6 spread out at its forward end. Figure 1 2b shows the preferred condition wherein the diameter D, of the circle circumscribing the free ends of the fins is at least twice as large as the calibre dof the shell body. (See Figure 12a).- It will be appreciated readily from the aforedescribed rounds embodying this invention, that when they are to be used with automatic or semiautomatic weapons, it is possible to use weapons which may, at any time, also be used for firing live rounds without making any modification to them.

Claims

1. A round of practice ammunition for firing from a weapon, the round providing a projectile of substantially the same external shape as a projectile provided by a corresponding round of live ammunition and having handling characteristics and containing substantially the same propellent charge as said corresponding round, the projectile being stabilised against drift and comprising a braking device comprising two or more elongate braking fins which are connected to the body of the projectile and extend longitudinally thereof when theiround is in its pre firing condition, which fins are adapted to open out from the body of the projectile by centrifugal force on firing of the round.

2. A round as claimed in Claim 1, wherein the braking fins comprise a portion of reduced rigidity extending thereacross in a region thereof at which the fins are subjected, on firing of the round, to the bending effect to the centrifugal force to which the projectile is subject.

3. A round as claimed in Claim 2, wherein the fins possess a reduced thickness at said positions.

4. A round as claimed in any one of the preceding claims, wherein the braking fins bear against the body of the projectile when the round is in its pre-firing condition.

5. A round as claimed in Claim 4, wherein the braking fins are so disposed with respect to the body of the projectile that their forward ends, considered in the direction of travel through a weapon barral are their free ends which move outwardly by centrifugal force on firing the round.

6. A round as claimed in Claim 5, wherein the braking fins are connected to the projectile body in a forward region thereof.

7. A round as claimed in any one of Claims 4 to 6, wherein the braking fins are formed integrally with a common central holding member by means of which they are held against the projectile body.

8. A round as claimed in Claim 7, wherein the holding member is clamped between the body of the projectile and a nose member thereof.

9. A round as claimed in Claim 7 or 8, wherein the holding member with the braking fins is stamped out of sheet metal and then placed in a predetermined three-dimensional configuration.

10. A round as claimed in Claim 9, wherein the sheet metal stamping is deep drawn to place it in its three-dimensional configuration.

11. A round as claimed in any one of the preceding claims, whose body is formed with one or more recesses in which the braking fins are fitted in such manner that they are not proud with respect to the projectile body when the round is in its pre-firing condition.

12. A round as claimed in Claim 5 or in any one of Claims 6 to 11 when appended to Claim 6, wherein a cartridge case fitted to the rear of the projectile body engages over the braking fins.

13. A round as claimed in any one of Claims 1 to 3, wherein the braking fins are disposed on the rear end of the projectile body, projecting rearwardly therefrom when the round is in its prefiring condition.

14. A round as claimed in Claim 13, wherein a cartridge case fitted to the rear of the projectile body engages over the projectile fins.

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15. A round as claimed in Claim 13 or 14, wherein a sleeve-like extension formed with longitudinally extending slots incisions or interstices defining therebetween said braking fins projects rearwardly from the rear end of the projectile body.

16. A round as claimed in Claim 15, wherein the sleeve-like extension is formed integrally with the projectile body.

1 7. A round as claimed in any one of Claims 13 to 1 5, wherein the sleeve-like extension is formed as a separate shaped part from the projectile body, the extension being so connected to the projectile body as to remain in contact therewith during flight of the projectile.

18. A round as claimed in Claim 17, wherein said shaped part comprises a central section from which the braking fins depend, and a forward extension of the central section, which extension has a diameter which is always smaller than the external diameter of the projectile body, said forward extension entering and being held in a correspondingly shaped recess in the rear of the projectile bodv.

1 9. A round as claimed in Claim 16, wherein the forward extension of the moulded part enters the said recess with frictional and/or a formlocking connection therebetween.

20. A round as claimed in any one of Claims 13 to 18, wherein the sleeve-like extension contains a lining member to intimate contact therewith and closed at its forward end.

21. A round of practice ammunition, substantially as hereinbefore described with reference to Figures 1, 2a and 2b, optionally modified Figure 3a or 3b, Figure 4, Figures Sa and 5b or Figures 6a and 6b of the accompanying drawings.

22:'A round of practice ammunition, substantially as hereinbefore described with reference to any one of Figures 7 to 11 of the accompanying drawings.