METHOD FOR SELF-PROPELLING PROJECTILE MANUFACTURING AND RESULTING PROJECTILES THEREOF

Abstract: This invention relates to a self-propelling projectile (20) of the type including a solid nose (21) and a propelling charge housing recess (28) communicating with a hollow space (128) containing the priming charge able to undergo a radial or lateral percussion. In particular, means (b) are foreseen that assure the projectile rear part (23) seal in respect to the explosion generated gas and further means (c; 34) that permit extraction of the unexploded projectile in case of malfuntionning. This invention relates also to the method for manufacturing the projectile.

Description: "METHOD FOR SELF-PROPEI;LING PRfJECIILE MXNUFACTURING AND RESULTING PR3JECTIT9 tesREoF" The present invention relates to self-propelling projectiles, in parti cular of the type wherein the priming charge is activated by a radial or lateral percussion. More specifically, the present invention relates to a method for manufacturing projectiles in question and to produ cts thus obtained. Self-propelling projectiles of this class are disclosed in Italian Patents Nrs. 866.111, 932,381 and 972.058 In these Patents self-propelling projectiles are described that include a projectile body which is suitably shaped, for instance as an ogive, a propelling charge housed into a recess made in to said body and a priming charge which is annularly placed and suitable to be activated by a radial or side percussion in respect to the said projectile body. The recess made into the projectile body and fil led with the propelling charge is rearwardly closed with a disc of destructible material, so that as a consequence of the percussion a priming charge explosion occurs which, either directly or throughout flash holes, primes the propelling charge and the latter causes the projectile expulsion from the firearm barrel, without leaving into the gun chamber the traditional. cartridge case to be ejected before the successive loa ding and firing of another projectile. In terms of operating easyness, firing speed and auxiliary problem eli mination (as for instance the temporary storage of cartridge cases fired with traditional weapons as installed on aircrafts and armoured means), the advantages of projectile of the above said class are evident and do not need further comments. However, also for the projectilesas set forth in said Patents, some pro blems and inconveniences have been noticed of remarkable importance in many applications, that in short can be summarized as follows: 1) In order to assure a full exploitation of gases as developed within the firing chamber and hence of the power as produced by the propelling charge firing, a remarkable snug seal is needed between the projectile external surface, the firearm chamber adjacent thralls and the barrel bore. 2) In case of misfiring or not-firing, the ejection of the unexploded projectile from the weapon results difficult. To these exquisitely operating problems there are to be added those connected with the production of projectiles in question. As a matter of fact, in the case Df projectiles as set forth in the previously mentioned Italian Patent 866111, many different precision machinings are reauired either to form the inwardly turned part of the bottom edge wherein the primer is contained with relatirg flash holes for connection with the propelling charge, or for the loading of the propelling charge. In the instance of projectiles as set forth in Italian Patents mars. 932381 and 972058, the relating drawings are sufficient to demonstrate the manufacturing complexities, primarily under the machining aspect and of the successive assembling of the different components of the projectile. Main object of the present invention is that of providing a self-propelling projectile wherein the inconveniences and operating problems as outlined above in short are substantially and advantageously settled. A more specific object of the present invention is that of providing a self-propelling projectile of structural features such to assure axial sliding of the projectile along the weapon barrel, after the percussion, and at the same time assuring an engagemnt with the weapon rifling such that any harmful axial wobble is prevented. Another specific oject of this invention is that of providing a self-propelling projectile of structural features such as to assure centering of the projectile in the firearm chamber. A further specific object of this invention is that of providing a self-propelling projectile having a rearward end or base equipped with means that can be engaged by the extractor hook of the weapon breech block, so that, in case of misfire, the recocking operation pcrmits extracting of the unexploded projectile from the weapon chamber. Still another object of the present invention is that of providing a method for the manufacturing of self-propelling projectiles in accordance with the invention of a reliable and simplified type, that will substantially avoid the industrial problems previously mentioned. These and other objects are attained with a self-ropelling projectile of the type including a shaped body having a solid forward portion and a tubular rearward portion, inside which there is formed a recess open towards the projectile base and closed with a layer of destruc tible material, in the said tubular portion there beingliouseda propelling charge in direct contact with a priming charge housed into an annular cavity, characterized by the fact that said cavity is formed between the internal surface of the said tubular rearward portion and a projecting skirt or flange, which is part of said solid forward portion, the surface of said skirt facing said cavity being fitted with flutings or corrugations substantially parallel to the projectile axis and projecting towards the interior of said cavity wall, wherein moreover the wall of said tubular rearward portion beginning from said destructable material layer shows a decreasing thickness and forms a projecting shoulder externally to the surface of said tubular portion, wherein the angle of inclination of its generating line should be within the range of 20 to 100 with respect to the projectile axis. In turn, the method for the manufacturing of the caseless projectile in accordance with the invention is characterized by the following operations: a) pressing of the projectile solid perform from metal wire or band; b) drop-forging of the preform to partially form said recess of said tubular rearward portion and said skirt delimiting the hollow space for priming charge housing, and corrugation manufacturing; C)drawing the perform for the completion of said tubular portion; d) loading of the priming charge into said hollow space and pressing to inform said slcirt in order to flare its base end projecting into said recess, approaching said base end to the adjacent wall of said tubular rearward portion; e) loading with a propelling charge and enclosing of the same with a layer of destructible material: f) rimming or partial bending of the base edge towards the interior of said tubular rearward portion. The features and advantages of the self-propelling projectile and method in accordance with the present invention will appear more clearly from the following detailed description made in connection with attached drawings, wherein: Figure 1 is a side view, in partial section, of the caseless projectile in accordance with the invention: : Figure 2 is a sectional view taken on the line 2 - 2 fig. 1; Figure 3 is a view similar to fig. 1 of another embodiment of the projectile of the fig. 1; Fipiires 4A, 43, SA, 53, 6A, 63, 7A, 7B, 8A, 8B, 9A, 93, 10, 11A, 113 12A, 123, are schematic views fo the manufacturing stages of the projectile of fig. 1. With reference to the drawings th illustrate without limiting purpose a preferred embodiment of the invention and manufacturing method, reference 20 generally indicates a projectile, self-propelled, adapted for actuation by means of a radial or side percussion, of the type especially convenient to semi-automatic and automatic weapon, but which may also be used for single firing. Projectiles of this caracter are usually contained into a clip inserted into the weapon, thereafter the breech block forcing the clip uppermost projectile or cartridge into the weapon firing chamber. The projectile 20 includes a body 21 preferably of one-piece character, incorporating a solid nose 22, which is often referred to as the bullet, and a rearward tubular portion or casing 23. loose 22 consists of a forward portion 24, which tapers rearwardly and outwardly, and a connecting portion 25, having a constant diameter the same as the maximum diameter of said forward portion 24; the-ma-cimum diameter of nose 22 and hence of the forward portion 24 is slightly less than that of the bore of the weapon for which the projectile is intended. The demarcation between nose 22 and casing 23 is effected by a narrow, rearwardly and outwardly tapered shoulder 26 from which said casing 23 progresses. The latter is of substantial ly constant diameter from the shoulder 26 up to a short distance from the base of said rearward casing 23 (as hereinafter described). The said short distance is defined by a plane passing through line (p) of fig. 1, from which the casing 23 forms an outwardly inclined bulging or shoulder (b) ,terminatinginto a portion (c), partially turned inwar- dl, which defines the edge of an opening 27, which permits communication between the interior of a chamber 28 in the rearward of the projectile casing 23 and the exterior. Internally of projectile 20, the internal surface of body 21 consists of a wall or base 29, limiting the chamber recess 28, and of an annular skirt or flange 30, being spaced radially inwardly from the outer wall of said casing 23, for defining therebetween an annular compart merit 128, being in free communication with chamber 28 throughout the annular neck 228 The annular compartment 128 contains a priming mixture (m), of any kroa3n character, which in assembling is forced into said compartment usually as moist dough. As may best be seen in figure 2, annular skirt 30, on its outwardly directed surface is provided with circumferentially spaced apart, vertically extended corrugations, substantially in parallel with the axis of projectile 20. Received within chamber 28 is the propellant charge 31, which ma be of any knolm suitable character, such as nitrocellulose, ballistites or double and triple base powders. multiple component explosives having varied physical characters, as for instance in the form of laminate, granulate, spheric granules, rod-like members, flake-like members. There may be moreover utilized propelling powders admixed with uat¯rproofing or not-waterproofing varnishes, with asphaltic binders or in any way suitable to form a mass filling the interior volume of chamber 28. It will be seen, however, that such propellant charge 31 is tightly packed into the chamber 28 of said casing 23, and is enclosed rear ;ardly by a wad,layer or operculum of destructible material 33,usually varnished or waterproofed, located inwardly of the above said plane (p). In the zone of said operculum 33 the wfall of said casing 23 gradually decreases in thickess towards the edge portion (c) for the purpose hereinafter illustrated. :;moreover, it has been found thatthe angle of inclination of shoulder (b) with respect to the projectile axis should be preferably within the range of-2 and 100, whilst the height of the bulging or shoulder (b), that is the distance between the base opening 27 and a plane passing through line (p) should be preferably within the range of 0,15 and 0,30 of the diameter of said casing 23. The latter diameter is greater than the bore (caliber) of the associated weapon, and at least equivalent but preferably larger than the diameter of the barrel inner rifling, so that projectile 20, upon firing, will. have sufficient forceful contact with the firearm rifling in order that the latter will impart the desired axial rotation thereto. The maximum diameter of shoulder (b) will be of such extent as to relate to the diameter of the diametrally constant portion of casing 23, or as that passing through line (p), in a ratio of preferably approximately 1. 01 to 1.05. Thus shoulder (b) shall have a maximum diameter greater than that of both the bore and the rifling of the related firearm, so that when projectile 20 is rammed therein bJP. operation of the breech block, shoulder (b), by reason of its relative thinness, will be radially compressed and thus diametrally reduced whereby a friction fit is brought about with assures that projectile 20 is in correct position for alignment with the firing pin, as schematically indicated at F. -oreover, the relatively thin-walled nature of casing 23 at shoulder (b) will thus assure an appropriate snug seal with the firearm bore, upon firing the full effectiveness of the explosive gases operating upon the projectile ( as gas leakages are prevented) being thereby utilized, without impeding the projectile travel through the firearm barrel. It will be worth mentioning that flutings or corrugations 32, inside the annular compartment128, markedly enhance the striking sensibility and hence the reliability of ignition, in that peaks and valleys of corrugations serve in the nature of anvils for the firing pin operating along F. In effect, the generally irregular surface developed by corrugations 32 causes a more effective compression of the priming charge mixture, which results in a greater reliability. In this connection, it will be moreover recognized that the projectile structure in accordance with the invention naturally develops in itself the anvil against which the priming mixture is compressed without need of inserts or auxiliary members in order to constitute such anvil. A last feature and important advantage of the projectile in accordance with the invention is its base conformance in that while shoulder (b) ensures centering into the barrel, the void space (34) provided between disc 33 and opening 27, as well as inward partial turning (crimping) of the rearward end of casing 23 ensure a particular interaction with the firearm breech block and its associated extractor hook. Effectively, this extractor hook, normally carried by the breech block, will normally interlock with the crimp(c)inside voidspace(34) It will be recógnised that when the projectile 20 is forced (as alrea dy explained) into the gun chamber of the firearm, it will be traveling at a relatively high rate of speed, so that when the breech block slams home, the inertia will force the projectile 20 a > Ja- from thc face of the block as far as the extractor hook will permit. Such play will thus allow for a variation in the location of projectile 20 within the chanber, but by reason of the shoulder (b) with the developed friction fit between projectile 20 and the gun chamber, the inertia is insufficient to cause projectile 20 to move from the bolt face. Bçt reason of the interengagement with the extractor hook, the breech block or bolt will remain in forward or closed position should a misfire occur. In such an eventuality., the firearm may be manually recocked to allow extraction of the unfired projectile from the chamber. The firearm will thus remain inactive until the defective projectile- has been removed. It will be appreciated that such a feature is of extreme importance with fast firing weapons since the chambers thereof are normally quite hot and would cause the propellant to explode in a very short period of time. Accordingly, projectile 20 of this invention is of most novel construc tion for bringing about a positive interlock with the breech block extractor and thus the above noted safety factor will'result strongly enhanced. Referring now to the modification illustrated in figure', the projectile of figure 1 is modified only in that within the exterior of casing 23, in contact with the bore and barrel riflings, corrugations 40 are provided in order to establish a gap into said contact thus reducing the sliding friction surface of projectile 20 within limits such to reduce the effort required by the projectile for its motion into the barrel and its exit out of the firearm. Consicering now figures 4 to 12, therein illustrated is the sequence of steps, in a preferred embodiment, of the method in accordance with the invention. It will be appreciated that almost all figures are of dual character showing the projectile or preform as sectional and as side views. s oreovert it will be worth mentioning the fact that operations illustrated below are normally known for persons skilled in the art or generally in mechanics thus permitting avoidance of execution details. The preform 50, as illustrated in figures 4A and 4B, is formed by pressing of a wire in order to obtain nose 22 with portion 24 and 25, as identified in figure 1, and a portion 51 wherefrom casing 23 of figure 1 will be made. Pressing (upon annealing, pickling and washing) will be followed by a first extrusion phase (figures 5A and 53), wherein the skirt or annular flanges 30 and wall 29 are obtained from portion 51, thus identifying already the annular compartment 128 wherein the priming charge will be contained. Upon completion of routine trashing, annealing, pickling and washing phases, a second extrusion (figures 6Aahd 6B) is made in order to complete annular skirt 30 (with related corrugations 32) and the annular compartment 128. Upon repetition of same operations as made after the first extrusion, the preform 50 is subjected to a drawing (figures 7A & 7b) wherefrom the rearward casing 23 andinterior of chamber 28 for the propellent charge is formed. After a washing, the drawing is completed (figures 8A & 8B) into dimensions desired for the projectile and primarily for rearward casing 23. Upon a washing and an equalizing (figures 9A & 93) of the projectile base, the primer (m) is forced into annular compartment 128 (figure 10). As already discussed, the primer is preferably of. a pasty character so that it will adhere to corrugations 32 wherefrom it will be retained upon drying. However, this fonction:is primarily carried out by means of deformation of the skirt 30 which is "radially forced so that its lowermost edms is flared towards the adjacent wall of interior of chamber 28 of casing 23. Annular neck 228 is thus formed through which the priming charge communicates with the interior of chamber 28. In the successive phase (figure 11A & 11B) the projectible is loaded with the propellant charge of any convenient physical character and che mical composition, and layer 33 is thereafter provided, preferably as an operculum of cardboard varnished with a waterproofing varnish. The invention, either for what attains to the caseless projectile or the manufacturing method, has been described in connection with the preferred embodiment, being understood that modifications and changes, conceptually and mechanically equivalent in character, are possible without exceeding limits thereof.

Claims: CLAIMS 1) A self-propelling projectile comprising a shaped body (21) having a solid forward portion(22) and a tubular rearward portion(23)internally forming a chamber(28) opened towards the projectile base and enclosed with a layer (33) of destructible material, within said tubular portion being contained a propellant charge(31) directly connected with a priming charge(m),contained into an annular compartment(128) and fired by means of radial or side percussion, characterized in that said annular compartment(l28) is formed by the inner surface of said tubular portion(23) and by a skirt or projecting annular edge(30),being part of said solid forward portion(22), the surface of said skirt(30) facing said annular compartment(l28) being provided with flutings or corrugations(32) substantially parallel to the projectile axis, said skirt or annular edge(30) being flared towards the adjacent inner surface of said chamber(28), characterized furthermore in that the wall of said rearward tubular portion(23), starting from said destructible material layer(33), is of decreasing thickness and forms a shoulder(b) having a larger diameter than that of said tubular rearward portion(23) above said layer(33) of destructible material. 2) A self-propelling projectile according to claim 1, characterized by said shoulder(b) having generating lines inclined with respect to the projectile axis by an angle within the range of 20 to 100. 3) A self-propelling projectile according to claim 1, characterized by the height of said shoulder(b), from said layer(33) of destructible material, being within the range of 0.15 to 0.30 the diameter portion of said tubular rearward portion(23) above the said layer(33) of destructible material. 4) A self-propelling projectile according to claim 1, characterized by the ratio of said shoulder diameter to the diameter of said tubular rearward portion being within the range of 1.01 to 1.05. 5) A self-propelling projectile according to claim 1, characterized by the open edge(c) of said tubular rearward portion(23) being partially turned inwardly, thus creating a void space(34) between said layer of destructible material and the projectile base opening(27)as being li- mites by said partially turned edge (c). 6) A self-propelling projectile according to claim 1, characterized by said destructible material layer 7) A method for manufacturing a self-propelling projectile according tto claim 1, characterized by operations of: (a) pressing of the projectile solid preform; (b)dropforging of preform for partially forming said chamber of said tutu lar rear.xard portion and said skirt delimiting the priming charge housing compartment, and forming of flutings or corrugations parallel to the projectile axis; (c) drawing of preform for completing said tubular portion; (d) placing of said priming charge within - said compartment -and pres sing for deforming said skirt thus flaring its base edge projecting into said chamber; ; (e) loading of propellant charge and enclosing of same with a destruc tible material layer; (f)rimming of these shoulder constitution and partial inward tur ning of the base edge of said tubular rearward portion. 8) A method according to claim 7, characterized by said preform pressing (stage a) being carried out starting from metal wire or band. 9) A method according to claim 8, characterized by said dropforging (stage d) being carried out in two partial subsequent phases. 10). A method according to claim 7, characterized in that said dra wing (stage c) being carried out in two successive phases. 11) A method as defined in claim 10, characterized by said (rarzingM being followed by equalizing of the projectile base.

Inventors: FIOCCHI, GIUSEPPE, GALLUZZI, GIOVANNI
Applicants: GIULIO FIOCCHI S.P.A.
Application year: 1981
Main classification: F42B5
IPC codes: B21K1, B21K21, F42B5