WO1999044006A1

WO1999044006A1 - Lead free bullet for small arms ammunition

Info

Publication number: WO1999044006A1
Application number: PCT/DK1999/000090
Authority: WO
Inventors: Frans Jørgen ANDERSEN
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-02-27
Filing date: 1999-02-26
Publication date: 1999-09-02
Anticipated expiration: 2000-08-27
Also published as: DK25998A; DK175171B1

Abstract

Lead free bullet (31), also known as a 'Green Bullet', characterised by being a bullet with a non-compacted core (41) of a loose aggregate consisting of (special) small flowing solids of an inert material non-hazardous to the environment and with no toxic effects to personnel, the bullet being characterised by having almost identical exterior ballistic properties as for those of the corresponding conventional lead-cored bullet except ballistic properties depending on the weight of the bullet, which might be less, equal to or larger than for said lead-cored bullet. The method of manufacturing includes a vibratory filling of the aggregate after the empty bullet jacket has been submerged in a filling equipment (51) containing the core aggregate.

Description

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LEAD FREE BULLET FOR SMALL ARMS AMMUNITION

The invention concerns a lead free bullet, also known as a "green bullet", for small arms ammunition up to calibre 12.7 mm and a method of manufacturing said bullet, the bullet comprising a conventional bullet jacket, finished like a conventional bullet with a narrow opening in the jacket in one end, normally the rear, just leaving out the physical feeding with and insertion of a solid core, said empty bullet being discharged from the output stage of a conventional bullet machinery and thereafter being provided with a non-compacted core being a loose aggregate, without any binder added, filling the cavity of the bullet jacket through said narrow opening by use of a novel filling technology for bullets, said filling finally being sealed and locked to the bullet jacket by a sealing agent applied to fill up the narrow opening of the bullet, said loose aggregate being made of an inert material non-hazardous to the environment and with no toxic effects to personnel.

In a global view small arms ammunition is widely used by armed forces and civil shooters in a variety of different calibres. The typical use of such ammunition is for service, hunting, training and target-practice purposes.

The bullet for a conventional round is typically characterised by consisting of a lead core surrounded by a jacket made of a copper alloy or copper-coated steel. The use of lead-cored bullets has a long tradition because of the high density of lead and a reasonable price as well, the purpose taken into consideration. The high density, and therefore a large amount of weight per unit frontal area of the bullet, imparts such bullet a favourable large ballistic coeffecient C₀ and thus a comparatively small decelleration during its flight, just as a large weight of a bullet in itself, at a given velocity of the bullet, is a measure for the bullets possesion of kinetic energy ! ₂ m x v² and in this the impact when hitting a target, being of the greatest importance as far as ammunition for service and hunting purposes concerns. Another important reason for using lead as core material is the ease with which it, due to its soft nature, can be formed by a rather low pressure, thus making a mass production at a reasonable price per unit possible. The manufacture of lead cores is an individual operation, not included in the operations of a conventional bullet machinery, with an output delivery consisting of a solid piece of lead, preformed by pressure into a core or slug of shape and dimensions almost identical to those of the cavity in the bullet jacket at the sequential stage for core feeding in the bullet machinery prior to the tapering and closing operations.

At said stage of operations the slug is to be fed into the machinery for being distributed and seated into the jacket, in the following operation being pressed firmly to fill the jacket with an extremely tight fit without any cushions of air between core and jacket, which is most essential in order to obtain a proper balance of the bullet along its bodyaxis, thus ensuring stability of the extremely fast spinning bullet in its trajectory. In the following operation the jacket is to be tapered and closed, said closing leaving a narrow circular opening with the surface of the lead core end being into view. During the following operations the bullet will be finished including a final seizing. Without a complete redesign of the conventional bullet machinery, if at all possible technically or economically seen, the use of any type of core different from the solid type is definitely impossible.

Belonging to the group of heavy metals lead for years has been under suspicion of being a serious hazard to health and to the environment, which nowadays is considered a proven fact stating that lead is dangerous in its metallic form and chemical substances hereof and as vapour. Consequently national and international law and regulations gradually impose restrictions on the use of lead, which in the foreseeable future may result in the use of lead for most purposes, possibly except ammunition exclusively for combat and service purposes, being banned. The regulations already in force in several nations, as far as shooting activi- ties are concerned, normally include the shooters having a legal obligation to clean up the shooting range and installations for lead contaminated material at certain intervals, such material being categorized as dangerous chemical waste, of which the disposal is extremely expensive.

When firing ammunition provided with a conventional lead-cored bullet with a narrow opening in the rear, a toxic effect to the shooter will be apparent from the products of combustion arising from vapourisation of lead from the rear of the bullet. At the end of the trajectory some bullets hitting a hard object will break into fragments on impact, while others hitting a soft material, e.g. the soil or a shelter behind a fixed target, may be less damaged, in both cases, however, resulting in land and materials being contaminated by lead. Even clean-up team members, when handling the waste material, may be in danger of being exposed to lead in the shape of dust, both into the lungs by inhalation and to the skin.

In order to ensure that the shooter by training and target-practice using lead free rounds will gain the necessary skill also for firing service rounds of the conventional lead-cored type, a useful lead free bullet should be characterised by having characteristics and trajectory as close as possible to those of a conventional lead-cored round, at least at a reduced range in compliance with the shooters requirements for fraining and target- practice purposes. Another useful type of a lead free bullet for special purposes should be characterised by having a greater weight than that of the corresponding lead-cored bullet of same size and shape, thus having a long flat trajectory and a high impact. It is obvious that all lead free types need to be characterised by having properties of interior ballistics e.g. chamber pressure not hazardous to the safe use of the firearm and securing the prober functioning of said firearm. Furthermore the change in physical properties of the bullet should not cause an unacceptable wear of the bore. On the other hand the lead free ammunition should be of a design suitable for mass production and to a reasonable degree cost- effective for both customer and manufacturer. A simple solution would consist in just replacing lead with another soft metal of a comparable density like that of lead, such optional choice of core material making it possible for the manufacturer to meet a most likely future request for both lead-cored and lead free bullets by utilizing his existing conventional bullet machinery for the manufacture of both types, simply by switching the feeding from one type of core to another. The constrain is, that no such metal or material is available, as metals of a density making it a reasonable choice for core making are characterised by being too hard or brittle to form by pressure during the specific core-fitting, tapering and closing operations of a conventional bullet machinery.

In the past various bullet manufacturers have made several attempts to develop a lead free bullet, untill now, however, resulting only in non- commercialized prototypes for demonstration purposes. Said prototypes may be divided into two different categories, such as jacketed bullets and not jacketed. The jacketed types are characterised by having different types of cores e.g. a solid core, of equal size and shape as the final cavity of the finished bullet delivered from the output stage of the bullet machinery, made of steel or copper being manufactured by machining or forming by pressure, or a corresponding solid core made of a metal powder added with a binder or mixed up with a polymer thereafter being hardened , all of these types being manufactured by use of a conventional bullet-macliinery, just by feeding with said solid cores instead of the preformed slug of lead. The use of said solid cores, however, involves the very inconvenient complication, that the core being fed into the bullet machine need to be a completely finished core of equal size and shape as for the cavity of the tapered and closed finished bullet jacket, due to the fact that further forming by pressure of such hard core being seated into the bullet jacket, to make it form and fit proberly like a soft core of lead, is simply not possible. As far as the core of metal powder added with a binder or mixed up with a polymer concerns said tapering and closing operations inevitable would crush the rear of the solid core. The not- jacketed types, making no use at all of the existing conventional bullet machinery, typically are bullets made of a solid material, such as steel or copper, by macliining or forming by pressure, or they may be made of a compound consisting of a metalpowder mixed up with a polymer or they may be made of pure plastic. The not-jacketed bullets of the compound or plastic type, due to their low weight, are mainly foreseen to be used at a very reduced range for fraining purposes, and for same purpose is known from US-P 3,898,933 a projectile, seeming to be of a similar design as this present invention but definitely quite different in all aspects, developed solely for training purposes and being characterised by having a bullet jacket specifically designed for easily to break into fragments upon impact resulting in a disintegration of the core into small metal powder particles of very low weight and with a shape resulting in a high drag coeffecient C_D versus Mach number, where C_D is a measure for the air resistance to a flying body while the Mach number means the velocity of a body divided by velocity of sound in air, said particles therefore having a high rate of decelleration, and in this a short range improving the safety of the shooting range. The core in said bullet is characterised by being a flowing metal powder composition filled into the bullet jacket at an intermediate stage of operations, said metal powder thereafter, by an individual operation, being compacted by pressing directly in the bullet jacket by using the jacket itself as a mold, thereby the metal powder being converted into a solid block, in the field of powder metallurgy called a "green compact", which is characterised by being brittle and having strenght properties like those of a lump of sugar. Due to a.o. the low density of a flowing metal powder, normally approximately 40 per cent of that of the same metal in a solid form and by that a large volume of the metal powder actually needed for the core when pressed, said filling with a flowing metal powder and the following compacting operation will exclusively be possible by discharging the preformed bullet jacket from the bullet machinery at the stage prior to the tapering and closing of the bullet jacket, and as an indi- vidual operation by use of a specific press equipment for powder metallurgical works outside the bulletmacliinery as well. After said core pressing the bullet should be fed back into the bullet machine for going through the remaining fήnshing operations. Obviously, technically seen, it is physically impossible through the narrow opening in an empty con- ventional bullet jacket already being tapered and closed, to press the core by using a punch due to the small diameter of the opening in proportion to the internal maximum diameter of the jacket.

Although many of the lead free bullets demonstrated or described in the past by manufacturers may have shown compliance with one or more of the desired properties discussed in the foregoing paragraphs, no lead free bullet, as far as to the inventorers knowledge, has been commercialized yet. Some of the prototypes, especially those with a hard solid core, tend to breake into rather large fragments on impact, often causing expensive damages to the installations in a shooting court or gallery.

Furthermore such bullets often ricochets, thus being a potential danger to personnel far beyond the normal safety distances of a shooting range. Besides said hard cores are rather expensive to manufacture. Bullets of the not-jacketed hard solid type show the same disadvantages as mentioned above, and furthermore they tend to imply an excess wear to the bore of the weapon. Said type of bullets is extremely costly to manufacture. Jacketed bullits of the type with a core of a metal powder compacted by a - 6 -

press operation would be extremely expensive and time consiiming to manufacture, and furthermore calls for huge investments in additional equipment for core pressing. As far as the jacketed bullets provided with a solid core of a metal powder added with a binder or mixed up with a polymer concerns, they will normally be of high cost and low weight compared with the conventional lead-cored bullet, causing a much reduced range. The not-jacketed bullets made of metal powder mixed up with a polymer are rather expensive to produce, and have shown a tendency to disintegrate during the flight or even in the bore before leaving the muzzle. Only a few of the various prototypes can be produced directly by means of a conventional bullet machinery, if not said machinery being drastically redesigned, while others will necessitate large investments in specific supplementary equipment or even a replacement for the bullet machinery. Thus, a cost effective commercialized lead free bullet having the desired properties does not seem to be available from any manufaturer at present.

The present invention seeks to provide a useful and produceable lead free bullet being characterised by having ballistic properties almost identical to those of the corresponding conventional lead-cored bullet, exept those properties depending on the weight of the bullet, said lead free bullet, by exclusively modifying the core, being adaptable for multiple purposes, among those both a light and rather inexpensive bullet for training and target-practice and a heavy bullet suitable for special purposes, said lead free bullet characterised by being easily manufactured mainly by means of a manufacturers existing conventional bullet machinery, without any need for expensive major technical changes of the machinery and its operations, thereby leaving the manufacturer an option for an uncomplicated and inexpensive switch over from a manufacture of lead-cored to a manufacture of lead free bullets and vice-versa, in order to meet a likely future request from the market for both types.

In accordance with the invention the objects mentioned above are accomplished, seen from both a technical and economical point of view, in a novel design of a lead free bullet and a novel method of manufactu- ring such bullet.

The invented bullet comprises a conventional bullet jacket finished exactly like a conventional bullet, having a narrow opening in the jacket in one end, being delivered from the output stage of a conventional bullet - 7 -

machinery, only leaving out the insertion of the solid core, resulting in a delivery of empty bullets from said output stage, thereafter being provided with a non-compacted core being a loose aggregate, without any binder added, said core finally being sealed from the outside by a proper sealing agent filling the small hollow space in the open end of the bullet which in addition locks the core to the bullet jacket. The aggregate used for the core in principle may consist of any kind of a solid material being in or converted into a flowing form and having a proper grain size and shape making an inflow through the narrow opening possible, so taking advantage of such natural existent opening in a conventional bullet to use it as an inlet for the flowing aggregate during the specific filling and finishing operations. In accordance with the above mentioned, there is in principle a wide choice of aggregates available for the filling, but actually, according to mathematics and the concrete results of the developments, allready succesfully veri- fled by test shootings, an aggregate consisting of small solid balls or pellets, spherical or near spherical in shape, due to the unique geometry of the sphere, provides the core advantageously properties such as a durable fixed consolidation in the jacket without any tendencies towards segregation and settlings, and a very high apparent density, thus making the bullet as stable in its flight as for the corresponding bullet provided with a conventional solid core of lead. To be more precise, one of the reasons why an aggregate consisting of small balls or pellets of almost equal size is vastly superior to other types of aggregates, e.g. metal powder, consisting of more or less irregular shaped particles or granules, is the unique geometri of the sphere, which means that a heap of spheres, being surrounded by a body and by proper means being stimulated one or more times, will incline towards consolidation into a dense mathematical well defined cluster. Mathematically it can be verified, that the theoretical effective filling of a cavity with spheres of equal size can be expressed ap- proximately by the formula

V_t = 0.741 x Vc - 0.11 x S_c χ D_s where V_t is the effective volume of the filling seen as a solid, V_c is the volume of the cavity, S_c is the surface area of the cavity and D_s is the diameter of said sphere. In accordance with the formula, theoretically seen, an apparent density close to 74.1 per cent of that of the solid material - 8 -

should be obtainable, if the diameter of the spheres is ignorable, which is far more than the apparent density of e.g. a metal powder, normally being characterised by having an apparent density well below 50 per cent. The open space between the spheres form a unique structure as well, all of them having same shape and size, and all of them being in mutual connection with a, mathematically seen well defined, free passage from one to another making a total of 25.9 per cent of the volume V_c of the cavity. For special purposes, where a maximized weight may be of importance, it is practicable to improve the density by repeating the filling operation whith an aggregate consisting of much smaller spheres than used for the first filling. Mathematically seen it should be possible by filling of said 25.9 per cent free space to optain a density as outlined above, so that by performing two filling operations as descriped a theoretically achieveable total apparent density should amount to 93.3 per cent. The specific use of this teaching for the development of a lead free bullet has shown remarkable results, proving a.o. that it is possible, by use of an aggregate consisting of balls made of steel and by performing only one filling operation, to manufacture a bullet extremely well suited for fraining and target-practice shootings. Further the results show clearly, that by using a very heavy materiel for the aggregate, e.g. tungsten which is impossible to form by pressure and extremely expensive to machine, it is possible to manufacture a bullet with a core-weight about 20 per cent higher than for the corresponding core of lead. The invented method of manufacturing said bullet is based on both the technology of the invented bullet and the physical nature and behavior of different types of aggregates as well as the fundamental idea of making it possible, by use of a rather inexpensive commercial aggregate and by means of an rather inexpensive equipment, to mass produce a competitive inexpensive lead free bullet for fraining and target-practice purposes, while on the other hand, it should also be possible, by use of same method and equipment to manufacture bullets of a normal weight for service and combat purposes, or even to manufactue extremely heavy bullets for special purposes. In order to avoid huge investments in new bullet macliinery for the manufacture of lead free bullets, the method utilizes the existing con- ventional bullet machinery in full to produce conventional bullets, only omitting the the insertion of a solid core of lead. The method does not interrupt or interfere with said bullet machinery, which instantly, if so wanted, can be switched over from producing lead free bullets to produce lead-cored bullets and vice-versa. The switch over of the bullet machinery to a lead free production is simply done by blocking the feeding with solid lead cores. The filling operation, by which the empty finished bullets, delivered from the output stage of the bullet machinery, are to be filled with a proper aggregate, is an individual manufacture by means of a very simple and inexpensive equipment, easily installed not necessarily at the same location as for the bullet machine. The filling equipment is characterised by having a very low power consumption and almost no waste of raw materials. It is possible with almost no limitations to design the equip- ment for an individual desired output rate. Due to the invented technology and method it is in principle possible to use an aggregate consisting of any kind of a solid material in a flowing form such as particles, granules, grains or small solid pieces such as pellets and spheres. For several reasons, however, not all of said aggregates are well suited for flowing through the rather narrow opening in the bullet jacket. Thus, most metal powders are characterised by having a marked tendency to agglomerate when flowing through a narrow passage such as a hopper or a funnel, which descripes the conventional method of filling a small space with a powder, thus blocking the inflow opening intermittently resulting in an unpredictable and non-uniform density of the filling. A conventional remedy against said tendency to agglomerate is the use of a vibratory feeder causing the powder to loosen, which is opposite to consolidate, as the vibrations excites the particles of the powder to shift position in random directions and thereby an easier flowing. Said remedy is not appropriate or helpful at all when filling bullet jackets with the definite aim to achieve the highest possible density, and furthermore the vibration often will cause the aggregate to segregate or unmix, as the coarse particles tend to collect near the surface, thus providing the bullet unbalance. An aggregate consisting of small solid pieces, such as spheres and pellets, have a much less tendency to agglomerate, actually under certain conditions it will behave almost like a fluid. The present invented method inverts the effect of vibration on a metal powder or small solids from being a loosening effect to be an effect that consolidates the aggregate. Furthermore the method utilizes the fluidlike nature of certain types of aggregates to support an optimized consoli- dation of the aggregate in the cavity of the bullet jacket. More precisely, the method is characterised by performing the filling of the bullet jacket - 10 -

by placing the bullet jacket or any number hereof - properly seated, in a particular tray or frame, in a vertical position with the small opening pointing upwards, said tray being designed with a number of holes for such proper seating and with a vibration facility connected - in a submerged position into a basin full of a proper aggregate. Said aggregate will now, due to gravitational forces, by free-falling through the narrow opening, fill the cavity of the bullet. To secure the proper flow of aggregate down into the cavity and for ensuring a proper dense consohdation of the aggregate in the cavity the filling process is being assisted by vibration of the bullet- jacket, which will excite both the aggregate in the cavity and the aggregate surrounding the bullet jacket to be easier flowing due to random movements of the particles as mentioned above. If not in an submerged position, the vibration of the bullet jacket, full of aggregate, would result in a loosening of the aggregate with a random tendency for the particles to jump up- wards and out of the bullet jacket. This is exactly the reason for the submerged filling, as the column of flowing aggregate above the opening in the bullet jacket, behaving almost like a liquid, will apply a compressive force in a downwards direction to the aggregate in the cavity, which again, in combination with gravitational forces, will force the small pieces of ag- gregate in the cavity to shift position mainly in a downwards direction when being vibrated, thus ensuring the best possible and dense consolidation of said aggregate. The frequency and vibrational forces applied to the submerged bullet jacket should be thoroughly determined considering the size and weight of the single piece of aggregate and the weight of the column of aggregate above the inflow opening. Depending on the shape and size of the pieces used for the aggregate, said consolidation will be much different and varying in properties of density and stability. This present method, however, essentially will improve the filling of a bullet jacket regardless of what type of aggregate being chosen. Furthermore the method is diametrically opposed to a filling by means of a hopper or a funnel, which is characterised by being an operation on the single bullet jacket, whereas the submerged filling is an operation on an arbitrary number of bullet jackets, more thousands at a time is easily practicable, making the method extremely suitable for an optimized mass production. After having completed the filling operation the tray with bullet jackets, full to the brim of aggregate, is lifted out of the basin and transferred to - 11 -

an operation consisting in removing the aggregate from the narrow opening in the bullet jacket leaving a small hollow space, which is easily done by one or more wiping movements in a horizontal plane by use of a prober bmshing device adjusted to a proper height. The final operation consists in providing the bullet with a proper sealing of the open end from the outside. Among more methods to establish such sealing it is preferred to apply or inject a small amount of a prober sealing agent into said hollow space, thus sealing the open surface of the loose aggregate and at the same time locking the core to the jacket as well, making the core and the jacket a connected whole. Said sealing is easily arranged by means of a row of injector nozzles for the desired number of bullets to be sealed simultaneously per of operation. In order not to jeopardize the ballistic properties of the bullet concerning drag forces and stability, the amount of sealing agent to be injected should be properly adjusted to leave the surface of the stiffened sealing agent level and at least some tenth of a millimeter below the brim of the bullet jacket. The invented method of manufacturing lead free bullets by means of Submerged Vibratory Filling furthermore has a pronounced built-in feature, as a repeated filling - performed as descriped above, but with an aggregate consitisting of much finer pieces than used for the first filling, preferably said finer pieces being of a size approximately 2.5 per cent or less of that of the pieces used for the first filling - will improve the density of the filling essentially. During the repeated filling, it is essential, by proper means, to prevent the aggregate from the first filling from any settlings and rearranging.

As mentioned in the foregoing paragraphs, the invented lead free bullet, filled with a rather inexpensive aggregate consisting of small spherical shaped balls of steel which is the preferred aggregate, has already proven in full to be a useful and produceable replacement for the conven- tional lead-cored bullet for training and target-practice purposes, thus eliminating any hazard to health and environment caused by lead in its various forms as, experienced in the past by firing bullets provided with a core of lead. Thanks to the invented method of manufacturing, characterised by being extremely suitable for an optimized mass production, and the invented bullet just mentioned above, characterised by having ballistics very close to a lead-cored bullet at a slightly reduced range, a lead free bullet, or "green bullet" of the invented type for framing and - 12 -

target-practice shootings is a novel, inexpensive and very attractive alternative to the lead-cored bullet, both technically and economically seen.

The invention will now be described by way of example and with reference to the accompanying drawings in which:

Fig. 1 is a plan view of a cartridge equipped with a lead free bullet in accordance with the invention; and

Fig. 2 illustrates a conventional lead-cored bullet at some particular stages of the sequential operations of a conventional bullet machinery; and

Fig. 3 is a partial view in longitudinal section of a conventional lead- cored bullet manufactured by means of a conventional bullet machinery; and

Fig. 4 is a typical layout of a commercial conventional bullet machine- ry; and

Fig. 5 illustrates a conventional bullet at some particular stages of the sequence of operations of a conventional bullet machinery for which the feeding with lead-slugs purposely has been blocked, resulting in the out- put being a finished bullet, just without a core - i.e. an empty bullet; and

Fig. 6 is a partial view in longitudinal section of an empty bullet as mentioned just above; and

Fig. 7 illustrates the invented metod of filling an empty bullet by means of Submerged Vibratory Filling in accordance with the invention; and

Fig. 8, 9 are views partially in longitudinal section illustrating the pre- paration of the bullet, full of aggregate, for being sealed and locked;and

Fig. 10 is a view partially in longitudinal section illustrating the sealed finished lead free bullet in a first embodiment; and - 13 -

Fig. 11 is a view similar to that of Fig. 10 illustrating another embodiment of a lead free bullet where the aggregate for the core instead of small solid balls or pellets consists of a metal powder in a flowing form.

Fig. 12 illustrates parts of the unique geometry of a sphere and some important mathematical properties essential for this present invention; and

Fig. 13 is a partial cross sectional view of three spherically shaped balls - belonging to the aggregate used for a first Submerged Vibratory

Filling - illustrating the improved filling effect by performing a second filling by use of a much finer aggregate.

Fig. 1 illustrates a cartridge 11 consisting of a conventional cartridge case 21 including propellant and primer and a lead free bullet 31'" in accordance with the invention, said bullet being of equal shape- dimensions, tolerances and finish as for a conventional lead-cored bullet, however, with a core of a loose aggregate consisting of a solid material in a flowing form and of a proper grain size and being non- hazardous to health and environment. The weight of the bullet may be less, equal to or larger than that of the lead-cored bullet.

Fig. 2 illustrates a conventional lead-cored bullet at a number of particular stages during its flow through the sequence of operations of a con- ventional bullet machinery. The numbers of operation referred to are indicative from among ten to fourteen operations in a sequence normal for a bullet machinery, depending on the specific type of bullet to manufacture. It will be noticed that there are two feeding stages for cups 22 and lead slugs 42 respectively, and only one discharge stage, the out- put stage, for me completely finished bullet 31".

Fig. 3 illustrates the conventional lead-cored bullet 31 " having a bullet jacket 32 , normally made of a cobber-zinc alloy or cobber-plated steeL, and a solid core 41' , normally made of pure lead or a lead-antimony alloy. The bullet has in its rear a narrow opening 33 remaining from the tapering and closing operations.

RECTIFIED SHEET (RULE 91) ISA EP - 14 -

Fig. 4 is an example of the layot of a commercial bullet machinery of a conventional modern design, and the typical sequence of operations for such machinery. It is notable, that such machinery is of a very compact design and with all the different operations of the sequence being inte- grated into the machinery as a whole.

Fig. 5 illustrates the same as mentioned above for Fig. 2, except that the feeding of the bullet machinery with lead slugs purposely has been blocked, resulting in an output delivery from the outputstage of empty bullets 32 being of equal shape, dimensions, tolerances and finish as for the normal output of lead-cored bullets. Such empty bullets is an indispensable basic delivery for the manufacture of the present invented lead free bullet. Although this is not an invention, as most bullet manufacturers have experienced empty bullets occasionally in case of a mal- function in the core feeding system, it is a purposely provoked "malfunction" which in combination with the invented filling and sealing technology makes the whole concept possible. Therefore the manufacture of empty bullets 32 is entitled Operation No. 1 in the invented method.

Fig. 6 illustrates the empty bullet 32 , in the rear having a narrow opening 33 into the cavity 34 . Said opening in accordance with the present invented method in the following to be used as an inflow opening for the aggregate.

Fig. 7 illustrates an important part, entitled Operation No 2, of the invented method of manufacturing lead free bullets by means of Submerged Vibratory Filling. As mentioned more times in the foregoing paragraphs, the preferred aggregate for the core filling consists of small solid pieces in form of balls or pellets in shape of spheres or at least near spherical, why this is the type of aggregate prescribed for this present illustration. It will be understood, that this should be no limitation for use of other types of aggregate such as e.g. metal powder and compositions hereof or nodules. The empty bullet 32 being transferred from the output stage of the bullet machinery to the filling equipment 51 now is to be seated with the narrow inflow opening 33 pointing upwards, into a particular tray 61 with a vibration facility 62 connected to make - 15 -

the bullet be subject of vibration during the filling operation, said tray now being placed in a submerged or flooded position H into a basin 71 containing a loose aggregate 41 " consisting of small solid balls or pellets. The aggregate, due to the ball shape characterised by flowing very easily, now by free falling through the narrow inflow opening, due to gravitational forces, will fill the cavity 34 , - properly stimulated by vibration of the bullet and the compressive force downwards from the column of aggregate characterised by the weight of the volume H x A_D , where A_D is the area of the inflow opening 33 which - due to the ball shape - provides the bullet a unique well-consolidated and predictable dense filling highly uniform for all manufactured bullets. After having completed the filling by at least one or, if so wanted, a repeated filling operation or a second filling with a much finer aggregate in order to optimize the filling by a filling of some of the free space between the balls from the first filling operation, the tray with full bullets should be lifted out of the basin for being transferred to the next operation.

Fig. 8 illustrates the bullet 32 , just having been transferred from Operation No. 2 full to the brim of consolidated aggregate 41", not yet a true core, now ready for going through Operation No. 3 which consists in removing excess aggregate from the inflow opening 33 in order to provide a small hollow space suitable for sealing and locking the core. It is convenient to use a crashing equipment, adjusted to a proper height, sweeping off the aggregate by a number of movements in a horizontal plane.

Fig. 9 illustrates the bullet 32 , just having been provided the small hollow space 35 in Operation No. 3 now ready for going through Operation No. 4 , which is the finishing operation consisting in sealing and locking of the consolidated aggregate 41", by injection or applying a prober sealing agent into the small hollow space 35. A preferred and cost effective method is a sealing by means of an array of injector nozzles for the desired number of bullets to be sealed simultaneously per operation. It is of great importance that the injector system has a feature making it possible to adjust the amount of sealing agent injected in order to ensure the stiffened sealing being level at least some tenth of a millimeter belov the brim of the bullet jacket in order not to affect the exterior ballistics of the bullet.

RECTIFIED SHEET (RULE 91) ISA/EP - 16 -

Fig. 10 illustrates as a first embodiment the finished bullet 31 consisting of the empty bullet 32 - from now on a true bullet jacket - and the now sealed and thus extremely stable core 41 of a loose aggregate consisting of small solid balls, in principle self-locking due to the structure of a ball-cluster, and ϊ-urthermore now being locked to the bullet jacket by the outer sealing 36 making the core and the bullet jacket a connected whole.

Fig. 11 illustrates a second embodiment, which is, except for the aggre- gate used for the core, in all aspects similar to the lead free bullet illustrated by Fig. 10. The bullet 31 ' consists of an empty bullet 32 and a core 44 - consisting of a metalpowder with a particle shape as included in the definitions on powder metallurgy stated by DIN 30 900 seite 4 Nr 2.3 and the corresponding ISO Standards or a composition hereof - said core being sealed by a sealing 36 .

Fig. 12 a,b,c informs of some of the unique properties of the sphere both geometrically and mathematically seen, properties actually being of the greatest importance for the development of the present invented lead free bullet and the invented method of manufacturing said bullet. From 12 b it is noticable, that two plane layers of spheres are absolutely uniform and have unique fit when joined together, which is one of the geometrical facts providing a very high density of the core. In Fig. 12 c it can be clearly seen how a heap or a pile of spheres can form a stack of a high densi- ty when stimulated by a compressive force and vibration - as long as the spheres are being prevented from escaping by being surrounded - in this present specific case - by a bullet jacket.

Fig. 13 illustrates how a repeated filling by use of an aggregate consisting of much smaller spheres can improve the density of the core by filling the free space between the larger balls from the first filling. Certainly a remarkable improvement not possible with any other shape of the small solids.

RECTIFIED SHEET (RULE 91) ISA/EP

Claims

- 17 -Claims

1. A lead free bullet for small arms ammunition up to calibre 12.7 mm comprising a conventional bullet jacket, finished like a conventional bullet with a narrow opening in the jacket, and a non-conventional core in the jacket, said core being a loose aggregate consisting of a number of small solid balls or pellets approximately of same size and spherical or near spherical in shape, made of an inert material non-hazardous to the environment and with no toxic effects to personnel neither in its sohd state nor as vapour, said aggregate being without any binder added filling the cavity of the bullet jacket, replacing the conventional solid core or slug, being thoroughly consolidated in the cavity thus constituting a characteristic tight and dense block-like cluster of balls, said cluster, due to the unique geometry of the sphere, characterised by being exstremely stable and of a self-locking nature, furthermore said cluster being effectively sealed and locked to the bullet jacket by a sealing agent applied to fill up said narrow opening in the bullet jacket, said loose core and the jacket thus being a connected whole in perfect balance along its spin axis when fired and with a drag coeffecient identical to that of the corresponding bullet with a conventional solid core, the loose core material being effectively and durable secured against any segregation or rearranging of material when subjected to different types of inevitable mechanical stress during the life cycle of the bullet including the eventual firing of the round.

2. A lead free bullet as claimed in Claim 1, but the loose aggregate being characterised by comprising two or more fractions, of which fraction number two is characterised by consisting of solid balls or pellets of a size approximately 2.5 per cent or less of that for fraction number one, and fraction number three has the same proportions related to fraction number two et cetera.

3. A lead free bullet as claimed in Claim 1 , but the loose aggregate being characterised by consisting of a metal powder without any preferred size of the particles and with a particle shape as included in the definitions on powder metallurgy stated by DIN 30 900 seite 4 Nr 2.3 of Juli 1982 and the corresponding ISO Standards or a composition of said metal powder. - 18 -

4. A method of manufacturing a bullet for small arms ammunition up to calibre 12.7 mm comprising a conventional bullet jacket with a narrow opening in one end, finished identically with a conventional lead-cored bullet by means of a conventional bullet machinery, just having omitted the insertion of a sohd slug of lead by blocking of the core feeding system of the bullet machinery, said blocking resulting in a delivery from the output stage of empty finished bullets, which is entitled Operation No. 1, said empty bullet now by means of Operation No. 2 , characterised as Submerged Vibratory Filling being provided with a core of a loose aggregate consisting of a number of small solid balls or pellets, spherical or near spherical in shape, according to which said empty bullet, or any number hereof, is to be properly seated and fixed in vertical position with the opening pointing upwards, into a particular tray with a vibration facility connected for making the bullet vibrate during the filling operation, said tray with bullets being placed in a submerged or flooded position into a basin full of aggregate, resulting in - due the easy flow of ball-shaped solids, especially when exited by vibration, and gravitational forces - said aggregate being free-falling through the narrow opening will fill the cavity of the empty bullet in which the aggregate will consolidate into a very dense characteristic ball cluster, properly stimulated by the vibration of the bullet and the compressive forces caused by the weight of the column of aggregate above the opening of the bullet, said bullets after the completed filling, still being seated in the tray, are lifted out of the basin now being transferred to Operation No. 3., which consists in removing aggregate from the narrow opening of the bullet by use of of a proper brasliing device wiping in horizontal movements leaving a small hollow space in the opening of the bullet jacket suitable for being filled with a proper sealing agent, which filling is the finishing operation entitled Operation No. 4. consisting in applying or injecting from the outside a small amount of a proper sealing agent into the hollow space just provided for, said agent thus sealing the open surface of the loose core aggregate, joining the core to the jacket as well, thus, when stiffened, making the core and the jacket a connected whole, - a lead free bullet. If so wanted to improve the filling the Submerged Vibratory Filling can be repeated one or more times. - 19 -

5. A method of manufacturing a lead free bullet as claimed in Claim 4 but the loose aggregate being characterised by consisting of a metal powder - without any preferred size of the particles and with a particle shape as included in the definitions on powder metallurgy stated by DIN 30 900 seite 4 Nr 2.3 of Juli 1982 and the corresponding ISO Standards - or a composition of said metal powder.