GB2437077A

GB2437077A - Primer cup and composition

Info

Publication number: GB2437077A
Application number: GB0607499A
Authority: GB
Inventors: Michael Ernest Saxby
Original assignee: UTM IP Ltd
Current assignee: UTM IP Ltd
Priority date: 2006-04-13
Filing date: 2006-04-13
Publication date: 2007-10-17
Also published as: GB0607499D0; WO2007119038A1

Abstract

A primer composition, possibly associated with a percussion cap or gun ammunition cartridge 4, comprises phosphorous, an oxidising agent such as one or more of potassium, ammonium or calcium chlorates or perchlorates, and one or more components of a latex binding agent, gritty filler and/or starch. The phosphorous component may be red phosphorous. The inert gritty filler may be in the form of ground stone, ground glass, feldspar, talc or silicate minerals with particle sizes of 5-150žm. The dry composition of the primer consists of 10-50% filler, 20-99% oxidising agent, 0.025-10% starch and approximately 6% red phosphorous. A method of preparing such a primer is also disclosed and includes adding 36% water to a dry composition of phosphorous, filler and starch, adding the oxidising agent before adding a suitable binding agent.

Description

Reduced Toxicity Primer and Non-lethal Ammunition Employing Novel

Primer

FIELD OF THE INVENTION

The present invention relates to ammunition, particularly non-lethal ammunition intended for use in training and war games. En particular the invention is directed to an improved design of primer cup, more particularly a cup with a rimfire primer, and the use of the improved cups in non-lethal ammunition. The Applicant is the proprietor of a number of patents directed to non-lethal ammunition. In contrast to the centre fire primer used in live ammunition of equivalent calibre, many of the Applicant's products utilise a rim fire primer which, in conjunction with a conversion kit for the firing weapon provides a reliably safe system for training in ::. the proper use of the weapon. The invention is directed to an improved design of rim fire primer cup, the use of the improved cups in the Applicant's products and * other manufacturer's similar products and a method for manufacture of the novel cups. **.

S

BACKGROUND ART * V * * S S...

The Applicant is the proprietor of a number of patents directed to non-lethal ammunition. In contrast to the centre fire primer used in live ammunition of equivalent calibre, many of the Applicant's products utilise a rim fire primer which, in conjunction with a conversion kit for the firing weapon provides a reliably safe system for training in the proper use of the weapon. The invention is directed to an improved design of rim fire primer cup, the use of the improved cups in the Applicant's products and other manufacturer's similar products and a method for manufacture of the novel cups.

Low powered training cartridges are known, and examples of such cartridges are disclosed in PCT98/00620, PCT/GB99/02859, PCT/6B99/02556, US 6427600, US6095051, US 6422149, US 6415718 and US 5492063. As explained in the Applicant's international patent application PCT/GBO1/00515, training cartridges are characterised in that they impart much less energy to a projectile than a live ("killing") round. Thus, whereas a live round may impart 800 ft/lbs of energy to a bullet and a shotgun may impart as much as 1000 ft/lbs of energy to the shot, training cartridges are much less energetic. For example, the energy imparted to a projectile by a training cartridge is typically less than 5 ft/lbs and more usually less than 4 ft/lbs. The term "training cartridges" as used herein therefore refers to such low energy cartridges, unless the context indicates otherwise.

The aforementioned training cartridges typically contain only a primer and do not contain a conventional amount of propellant. Consequently, they must be carefully designed to ensure that there is sufficient energy both to recycle a weapon and eject a projectile such as a bullet. Many training cartridges, see for example the cartridges disclosed in the patent documents supra, are of the *.. expanding type in which the body of the cartridge comprises a "piston and s.., cylinder" arrangement. With such cartridges, part of the energy of the primer is I...

used to force the piston and cylinder apart (i.e. expand the cartridge) and drive :.:::. the rear end of the cartridge back to recycle the weapon, and part of the energy is used to discharge the projectile from the front end of the cartridge. Careful * control of gas flow within the cartridge is required in order to make sure that the .:.. projectile is discharged at a consistent and appropriate velocity and that the I...

s.-" weapon is recycled at every firing.

Prior to the filing of PCT/GBO1/00515 (so far as the Applicant is aware) training ammunition, and most live military ammunition, was of the centre fire variety.

Exceptions are certain 0.22" (5.56mm) rounds generally used in target shooting (and occasionally in military training) which are of the rimfire type. The difference between rimfire and centre fire primer cartridges is illustrated by Figures 1 and 2.

Figure 1 shows a sectional elevation through the primer for a centre fire primer cartridge. The primer comprises a cup or can 2 formed from, for example, nickel plated brass, and containing a suitable pyrotechnic primer material 4. An anvil 6 is set into the front of the can 2 to close the can and retain the primer in place.

As the anvil is inserted into the can, the protruding central part 6a of the anvil greatly compresses the primer to create a compressed region 4a which is highly sensitive to shock. The region 4a which is sensitive to shock has an approximate width I, and this represents the impact area for the firing pin of a centre fire weapon. Thus, a centre fire firing pin will impact against the impact area and further compress the primer between the wall of the can and the anvil thereby detonating the primer. However, the firing pin of a rimfire primer weapon would impact against the can outside the impact area I and hence would not detonate the primer.

A primer for a rimfire primer cartridge is shown in Figure 2 and comprises a cup or can 102, the closed end of which is formed to provide a hollow rim area 103.

A pyrotechnic primer composition 104 is placed in the can and the can is spun thereby forcing the pyrotechnic material into the hollow rim area 103. With the a...

rimfire primer of Figure 2, the impact area I' is annular in shape and extends around the rim of the primer. As can be seen from Figures 1 and 2 together, for :.:::. cartridges of the same calibre, there will be a dead zone S between the impact region I of a centre fire primer, and the impact region I' of a rimfire region in * which any impact will not detonate the primer. When a cartridge containing the primer of Figure 2 is placed in a rimfire primer weapon and the weapon is fired, ** the firing pin strikes impact area I' and compresses the pyrotechnic composition between the two walls 103a and 103b of the hollow rim region 103, the shock imparted to the pyrotechnic composition causing it to detonate.

Although training cartridges that are constructed to provide consistent low energy discharge of bullets are generally safe per Se, safety problems can arise when live killing cartridges are inadvertently mixed with or substituted for low powered training cartridges. As stated above, all of the known existing training cartridges use centre fire type of primers which are very similar and often identical to the types of primers used in the equivalent live killing cartridge for a particular gun type. Attempts have been made to prevent confusion between the two types of cartridge by modifying the gun so that it will not fire the cartridge type usually fired from the gun, but will only fire a training cartridge.

Unfortunately, this safety feature can sometimes be bypassed by using a different live cartridge type which, when chambered, fits the gun, or by using damaged live cartridges. In such circumstances, firing live cartridges rather than training cartridges can result in serious injury or death.

At present, non-lethal, rimfire ammunition such as that described in the aforementioned publications of the Applicant use conventional primer compositions. Such primer compositions often contain heavy metal elements as their principle components. For example heavy metal elements as their principle components. For example, lead styphnate is typically used as a main energetic component; barium nitrate is a common oxidant and antimony suiphide is a common fuel. The presence of heavy metal elements in priming compositions is undesirable due to environmental concerns and priming mixtures containing *.* strontium nitrate as an oxidant have been proposed (US 4 693 2010) in order to s.

*.... avoid the use of heavy metals. S...

: * Although the use of both potassium dinitrobenzofuroxan (KDNBF) and S...

diazodinitrophenol (DDNP) as energetic ingredients (US 4 693 201), is known, *55 the use of KDNBF as the sole energetic ingredient results in primers that are :.. inconsistent or insensitive in their performance. Although this problem can be *:::: partially overcome through the addition of tetrazene as a sensitiser to the KDNBF or DDNP mixture, the long term stability of the resulting mixtures is poor, leading to an explosives hazard.

Primer mixtures containing KDNBF, tetrazene and strontium nitrate are known.

Such mixtures can be formed through either a wet or a dry mixing process.

However, a disadvantage with this type of primer is that, in general they are frequently too energetic and cartridges containing these primer compositions often burn too rapidly upon ignition, which is undesirable.

Cartridges used for training munitions are preferably designed to mimic real-life situations as much as possible without the need for extensive safety measures.

Such cartridges differ from those used in live ammunition principally in the energy at which the bullets are expelled from the muzzle of the gun. Live ammunition is typically expelled from the barrel of a gun at energies of over 60 ft lbs (81.35 joules) whereas the cartridges of training munitions are typically expelled at 4 ft lbs (5.43 joules). Thus, although it is known to use training cartridges containing both a primer and a propellant, the use of such cartridges is associated with relatively high energy and necessitates the use of bulky and expensive protective clothing, which means that training does not take place under realistic circumstances.

There are several types of training ammunition available. These include live training ammunition, live low energy training ammunition and low energy man on man training ammunition.

Live training ammunition is designed to allow shooting in areas and ranges in * which the danger zone is below that of live combat ammunition. These products can still kill but their range is reduced. S.. * . S...

: *.. Live low energy training ammunition is designed to further reduce the danger S.., zone and risk of fatal injury. It also reduces the damage caused to training areas. These products are still dangerous and cannot be used man on man. * . C...

Low energy man on man training ammunition is designed to eliminate the risk of fatal and minor injury during firearms training. The training of man on man is the nearest and most realistic training for real life combat situations. The guns muzzle energy must be kept below 3 ft/lbs and the projectile velocity kept below 400 ft/sec if even minor injury [broken skin] is to be eliminated. Protective clothing is still worn to cover eyes, ears, face, throat and bare skin to further reduce the risk of minor injury such as bruising.

In order to obviate the need for extensive protective clothing in training exercises and to enhance the realism thereof, double primer propellant free cartridge has been proposed. Such cartridges can be used in live ammunition but find particular application with training ammunition. Cartridges of this type are described in US patent number US 6 422 149 and have already been discussed above. Such cartridges typically comprise a front primer positioned adjacent the bullet to be expelled from the cartridge and a rear primer positioned adjacent the rear end of the cartridge against which the firing pin impacts when the gun is fired. Impact of the firing pin on the rear primer results in ignition of the primer composition present therein and causes a projectile (typically plastic or steel ball) to be driven at high energy against the front primer. Upon impact of the rear primer driven projectile against the front primer, ignition of the front primer composition occurs and causes a bullet to be expelled from the barrel of the gun.

Figure 4 illustrates an embodiment of a double primer cartridge.

The choice of primer compositions used in both the front and rear primers will depend upon the application in which the cartridge is to be used. The primer compositions of the rear primers tend to be relatively energetic to ensure that * despite the relatively low energy at which the firing pin impacts the rear primer, :.. efficient ignition of the primer composition occurs and results in the ball being a...

driven at relatively high energy against the front primer. Typically the rear : ** primer provides energies of 10 to 30 ft lbs (13. 56 to 40.67 Joules) upon ignition.

If the cartridge is to be used for live low energy training ammunition, the priming composition of the front primer is also itself relatively energetic to ensure that the energy at which the bullet is expelled from the barrel of the gun ". is relatively high. Typically if a double primer propellant free cartridge is to be S...

use for live low energy training ammunition, the front primer suitably provides energies of 5 to 10 ft lbs (6.8 to 13.6 Joules) upon ignition. If the cartridge is to be used for low energy man on man training ammunition, the priming composition of the front primer is less energetic to ensure that the muzzle energy of the bullet expelled does not exceed 3 ft lbs (4.08 Joules).

The use of the double primer propellant free cartridges described above has made it possible to better control muzzle velocities. Using known primer compositions (such as lead styphnate) muzzle velocities not exceeding 2ft/lbs (2.72 Joules) have been observed for the Applicant's Man Marker Rounds (MMR) and for Live Low Energy Reduced Range (LERR) ammunition the muzzle velocities not exceeding 8ft/lbs (10.87 Joules) have been achieved.

However, the use of primer mixtures containing lead styphnate as an energetic component, for example, in double primer propellant free cartridges frequently results in inconsistent and unpredictable results. It is not unusual for a double primer propellant free cartridge either to fail to fire the bullet out of the muzzle or to be expelled at a rate which greatly exceeds the desired muzzle velocities for training munitions due to the rapid and unpredictable burning of the lead styphnate.

There is, therefore, a need for a priming composition that is free of toxic heavy metals, provides consistent and controlled burning on ignition and is suitable for use in both live and training munitions, particularly in double primer propellant free cartridges.

SUMMARY OF THE INVENTION

SI

In accordance with a first aspect of the present invention, there is provided a primer cup for a training cartridge characterised in that the primer composition : .. comprises phosphorus and an oxidising agent. Depending upon the required I...

energenicity of the primer further optional components may also be present.

These additional components include one or more of a gritty filler, a starch and a :.::.. binding agent. * S S..

The phosphorus is preferably red phosphorus rather than white or black phosphorus due to its greater stability and reduced toxicity compared to white phosphorus, for example. The phosphorus acts as an energetic agent and the amount of phosphorus present will depend upon a number of factors, which include the particle size of the phosphorus, the method used to initiate ignition of the primer compositions, including the force of impact, whether the primer composition is to be used in live or training ammunition and if it is to be used in a double primer propellant free cartridge, whether it is to be placed in the front or rear primer. The presence or absence of one or more additional components such as a gritty filler, a starch and a binding agent will also influence the amount of phosphorus present.

If the composition is to be used in live ammunition or in the rear primer of a double primer propellant free cartridge, for a maximum particle size of 50 pm, the amount of phosphorus suitably comprises 1.1 to 10.0 % of the dry weight of the primer composition. Preferably the phosphorus comprises 4 to 8% of the dry weight of the composition, especially 6% of the dry weight of the composition. Under these conditions energies in the range 10 to 30 ft lbs (13.56 to 40.67 Joules) can be achieved upon ignition. If the particle size of the phosphorus is larger, a smaller amount of phosphorus may be required, depending upon the energies required from the primer and the method of impact. Given these requirements, it will be within the skill of a skilled person to determine the optimum amount of phosphorus required for any particular application. However, for a phosphorus particle size of 75 to 500pm, the amount of phosphorus suitably comprises 0.5 to 7.0 % of the dry weight of the **** composition, preferably 1.0 to 6.O% by weight of the composition and especially 2.5% by weight of the composition.

: * If the composition is to be used in low energy man on man training ammunition, * for example in the front primer of a double primer propellant free cartridge, the amount of phosphorus suitably comprises 0.25 to 5 % of the dry weight of the :::. composition. Preferably the phosphorus comprises 0.5 to 3% of the dry weight *. of the composition, especially 0.5 to 1.0 % of the dry weight of the composition. * ***

Under these conditions energies in the range 1.5 to 3.5 ft lbs (2.03 to 4.74 Joules) can be achieved. Energy levels of 1.5 ft lbs (2.03 Joules) have been obtained with double primer propellant free cartridges using either 1.5% by weight of phosphorus having a particle size of 5Opm and a steel ball or 2.0% by weight of phosphorus having a particle size of 5Opm and a plastic ball. If the particle size of the phosphorus is larger, a smaller amount of phosphorus may be required, depending upon the energies required from the primer and the method of impact. Given these requirements, it will be within the skill of a skilled person to determine the optimum amount of phosphorus required for any particular application.

The amount of phosphorus used in the primer compositions will also depend, in part, on the type and presence of any additional components. If a gritty filler is present, the amount of phosphorus required will be less. The amount of phosphorus will also depend upon the particle size of the gritty filler; as the particle size of the gritty filler increases less phosphorus, in general, is needed.

Since some of the further components such as starch or binding agent do in themselves increase the rate of burn and or the amount of gas provided by the primer composition, the amount of phosphorus used will also depend upon the presence and nature of these additional components. If a binding agent or a starch is present, less phosphorus will be required if these components do in themselves increase the rate of burn and or the amount of gas provided by the primer composition. The effect of the additional ingredients on the rate of burn of the primer compositions can be readily determined by comparing the burning properties of the compositions with and without the presence of the additional : components and changing the amount of phosphorus present if necessary.

. In general phosphorus having a particle size in the range 10 to 500 pm can be S...

used in the preparation of the primer compositions of the present invention. It s.: will be appreciated from the foregoing discussion that if the primer composition is to be used in training ammunition or in the front primer of a double primer * . propellant free cartridge (for use in live or training ammunition), particle sizes in the range 10 to 200 pm can be used, with particle sizes in the range 10 to 50 pm being preferred. If the primer composition is to be use in live ammunition or in the rear primer of a double primer propellant free cartridge (for use in live or training ammunition), particle sizes in the range 40 to 500 pm can be used, with particle sizes in the range 100 to 500 pm being preferred.

A stabiliser may also be present in the event that the components of the primer composition are found to degrade over a period of time. Potassium carbonate may suitably be used as a stabilising agent. A skilled person will be aware of other stabilising agents that may also be used.

The oxidising agent may be any oxidant that reacts with the other components of the primer composition upon ignition only. The oxidant must be sufficiently stable so that spontaneous ignition of percussion caps containing the primer mixture does not occur in storage. Suitable oxidants include nitrates, bromates, lodates, chiorates, perchiorates, peroxides and oxides. Typical oxidants include potassium chlorate, potassium perchlorate, ammonium chlorate, ammonium perchiorate, calcium chlorate and calcium perchiorate. The use of potassium chlorate is particularly preferred, since it has been found that its presence means that the activation energy required for ignition of a primer composition containing this oxidant is negligible.

The amount of oxidant present will depend upon whether the composition is to be used in live or training ammunition or in a front or a rear primer of a double primer propellant free cartridge. In addition, the amount of oxidant present will depend upon whether any additional components such as a gritty filler, a starch component or a binding agent are present. The oxidant suitably comprises 20.0 to 99.0% by weight of the primer composition if no gritty filler is present, :: preferably 40.0% to 99.0% of the dry weight of the composition and especially * S II .. 97. 00% by dry weight of the composition. In a particularly preferred : ** embodiment of the first aspect of the invention, the composition comprises * 97.OO% of potassium chlorate of the dry weight of the composition and no gritty S..

filler. Such compositions find particular application when used in a front primer for a double primer propellant free cartridge.

* * ..

If the composition includes a gritty filler, the oxidant suitably comprises 20.0 to 60.0% by dry weight of the composition, preferably 40.0 to 60.0% by dry weight of the composition and especially 60.O% by weight of the dry weight of the composition. In a particularly preferred embodiment of the first aspect of the invention, the primer composition comprises 60.0% by weight of potassium chlorate and 29.5 to 33.O% by weight of a gritty filler. Such compositions find particular application for use as a rear primer in a double primer propellant free cartridge.

The presence of a gritty filler prevents spontaneous explosion of the active ingredients of the primer and provides sufficient friction on ignition of the primer to ensure that controlled and efficient burning occurs. Examples of suitable fillers for use in the primers of the first aspect of the invention include ground stone, glass, talc, feldspar and silicates of diatomaceous earth minerals. Preferably the inert filler is ground stone. Preferably the ground stone has particles in the range to 150pm.

The presence or otherwise of a gritty filler depends upon the desired muzzle velocities required and whether the compositions are to be used in live or training ammunition or in the front or rear primer of a double primer propellant free cartridge (for use in either live or training ammunition). If a composition is to be used in the manufacture of a primer for training purposes such as in the front primer of a double primer propellant free cartridge the composition will suitably either contain no filler at all or will typically contain a filler such that its amount and particle size result in a primer having an energy of 1.5 to 3. 5 ft lbs (2.03 to 4.75 Joules) upon ignition.

". If the composition is to be used in the manufacture of a primer for live * .. I *". ammunition or in the rear primer of a double primer propellant free cartridge * as S (either for training purposes or otherwise) the composition will suitably contain .:.. inert fillers having larger particle sizes. Typically the inert fillers for use in such applications have particle sizes in the range 60 to 120pm. Where an inert filler is * * present, it suitably comprises 10.00 to 50.00% of the dry weight of the composition, preferably 25.00 to 35.00% of the dry weight of the composition, especially 29.50 to 33.00% of the dry weight of the composition. In a particularly preferred embodiment of the first aspect of the invention, the inert filler comprises 29.5 to 33.00% of the dry weight of the composition of the primer composition.

A starch component may be included in the primer mixture to facilitate the controlled burning of the primer mixture on ignition and thus the controlled generation of gases associated with combustion. It will be appreciated that the rate of combustion of the primer mixture of the present invention depends to a large extent on the amount and the type of the starch component present. The starch component typically comprises between 0.025 and 10.00% by weight of the dry weight of the primer composition. Preferably the starch component comprises 0.75 to 5% by weight of the dry composition, especially 1.00 to 3.00% by weight of the dry composition. It will therefore be appreciated that the presence of a starch component is associated with a higher gas production compared to compositions in which none is present and that primer compositions containing starch will most suitably be used in either in live ammunition or in the rear primer of a double primer propellant free cartridge (either for training purposes or otherwise) where higher energies are required. Although compositions for use in training ammunition (including those used in the front primer of a double primer propellant free cartridge) may contain starch, the amount and type of starch present will depend upon the other components present and desired energenicity.

Suitable starch components include powders derived from sources such as paper, cellulose, corn, rice, wheat, potato, maize and barley. In general it is preferred that when a starch component is present in a composition, the ratio of starch to oxidant is of the order of 1:6. Particularly good results have been *..

achieved through the use of cornflour. In a particularly preferred embodiment of the first aspect of the invention, the primer composition contains 0.025 to 10.00% of cornflour by dry weight of the composition, particularly 0.75 to 5% by S..

dry weight of the composition and especially 0.50 to 4.00% by weight of the dry composition. For preferred compositions including cornflour the ratio of cornflour * ,..

, to potassium chlorate is 1:6. Such compositions find particular application as the rear primer of a double primer propellant free cartridge (either for training purposes or otherwise).

The primer composition of the invention preferably contains one or more binding agents, the presence of which facilitates the formation of the primer composition into a paste and its loading into percussion caps for subsequent insertion into a cartridge. Preferably the binder doesn't burn or requires a very high activation energy in order for burning to occur. Any suitable binding composition that facilitates the formation of a paste can be used, providing the storage stability of the composition is not compromised. Examples of suitable binding compositions include latex emulsions such as BAL, shellac, resins, glues, lacquers or any of the polysaccharides (such as gels or gums) used for setting or thickening purposes within the food industry or used as adhesives. Synthetic vinyl based polymers can also be used as can wall paper paste. Gelatines, alginates, celluloses, amyloses and other polysaccharides having the desired properties to facilitate the formation of a paste are known to a person skilled in the art.

However, preferably the binding agent is a wall paper paste comprising carboxymethylcellulose and sodium hydroxymethylcellulose that has optionally been formaldehyde treated. Preferably the wall paper pastecomprises 0.25 to 0.90% of the dry weight of the composition, especially 0.50% of the dry weight of the composition.

In a most preferred embodiment of the first aspect of the invention, the primer composition comprises 6.00% red phosphorus, 6O.OO% potassium chlorate; 29.5 to 33% inert filler, 0.50 to 4.00% cornflour and 0.5% of wallpaper paste by dry weight of the composition. This composition is suitably used in live ammunition or in the rear primer of a double primer propellant free cartridge (for either live or training purposes). I...

I

In a further preferred embodiment of the first aspect of the invention, the primer 1:: composition comprises 2.00% by weight red phosphorus, 97.00% by weight potassium chlorate, 0.50% by weight of a wallpaper paste and 0.50% by weight * * of BAL latex binder. All weights are quoted with reference to the dry weight of the composition. This composition is suitably used in training ammunition, particularly in the front primer of a double primer propellant free cartridge.

It is known that primer compositions can be prepared through the use of either wet mixing or dry mixing techniques. Wet mixing techniques have been found to produce the most homogeneous products but require the use of a drying step. It will be appreciated, however, that the drying of a bulk volume of a primer composition is inherently associated with the risk of explosion. Although dry mixing techniques can be used in the production of primer compositions, the technique is less suited for the production of bulk quantities of the primer composition and the homogeneity of the resulting compositions, generally, is not as good as that achieved through the use of wet mixing techniques.

The compositions of the present invention are, therefore, preferably prepared through the use of a wet mixing technique and a second aspect of the invention provides a method for the preparation of the primer compositions according to the first aspect of the invention. Typically the wet mix comprises 25g of water per bOg of dry ingredients. To prevent the risk of explosion, the red phosphorus and oxidant are only mixed together in the presence of water.

For the preparation of a composition suitable for use in a front primer of a double primer propellant free cartridge, phosphorus is firstly added to water and thoroughly mixed. Potassium chlorate is then thoroughly incorporated into the mixture and finally the binder (BAL and/or wallpaper paste) is added. The resulting paste is then loaded into primer caps and dried in a drying oven.

Potassium carbonate may be added to the mixture to improve its long term stability in the event that the stability of the dry composition is less than *. optimal. I...

** For the preparation of a composition suitable for use in live ammunition or in a : *s'* rear primer of a double primer propellant free cartridge water is added to a dry * mixture of red phosphorus, inert filler and the starch component. The oxidising S. agent is then added to the wet mixture and thoroughly combined therewith.

::. Finally the binding agent is added to the mixture which results in the formation of a workable paste. The resultant paste is then metered into suitable containers for each application and then dried.

In a preferred embodiment of the second aspect of the invention, water is added to a dry mixture of red phosphorus, inert filler and cornfiour to give a liquid slurry. Potassium chlorate is then added to the liquid slurry and mixed thoroughly. Wall paper paste is then added to the resulting mixture to give a paste, which can be readily loaded into the percussion caps used in cartridges.

The compositions are preferably dried at a temperature of between 60 C and 100 C. If it is desired to dry at 100 C, it is preferably to include a BAL latex binder in the composition to prevent shrinkage of the dry composition away from the wall of the cup. Drying at 60 C results in less shrinkage.

Desirably, the primer is further characterised in that the primer composition is embodied in a stainless steel cup. This is in preference to the conventionally used brass cup which, the inventors have found, is prone to corrode in the presence of red phosphorous.

Desirably, the primer composition is embodied in a rim of the primer cup.

In another aspect, the invention comprises a training cartridge which includes the primer composition and primer cups of the invention.

Desirably, the cartridge is a double primer cartridge comprising a posterior (rear) portion and an anterior (front) portion, the posterior portion comprising a recycling mechanism, the recycling mechanism being initiated on activation of a primer to cause the weapon to be recycled. Activation of the rear primer may also cause the activation of a second primer in the anterior portion which second ::::. primer optionally propels a projectile from the cartridge. In other embodiments a pressure or shock wave resulting from activation of the rear primer activates the * second (front) primer. In other embodiments the front primer creates a noise or :. flash without propulsion of a projectile. S..

S

* In a preferred embodiment, the recycling mechanism comprises a moveable :.. member which is slideable rearwardly towards a breech block, sliding being S...

...* responsive to a reaction caused on initiation of the primer composition on firing of the firearm to propel the moveable member in a rearward direction against the breech block of the firearm so as to recycle the firearm.

Optionally, the anterior portion is provided with a nose portion which is suitable for receiving a projectile, and further includes a source of energetic material located in the anterior portion, the energetic material being initiatable by a reaction produced on activation of the primer composition to cause propulsion of the projectile from the cartridge.

Optionally, the anterior portion includes a gas generating means for providing gas within the cartridge, which gas generating means causes both propulsion of the moveable member and the projectile.

Optionally, the moveable member is in the form of a piston or cylinder slideably engaged respectively with a cylinder or a piston.

In another option, the energetic material is initiated by the shock or pressure wave produced on initiation of the gas generating means.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention will now be described with reference to the following non-limiting examples. Variations on these examples falling within the scope of the present invention will be apparent to a person skilled in the art.

Examole 1 A primer composition was prepared by adding 36 g of water to a dry mixture containing 6g of red phosphorus, 33g of inert filler and 0.5g of cornflour. 60g of potassium chlorate was added to the wet mixture and thoroughly combined.

0.5g of wallpaper paste was added to the resulting mixture and stirred until a " paste-like consistency was achieved (15 -30 seconds). The resultant paste-like mixture was metered into a stainless steel cups and placed in a drying oven.

:,::,. The use of the percussion caps of example 1 in training ammunition resulted in S...

..... an impact energy of the cartridge projectile of 3 ft/lbs or less.

Example 2

A primer composition was prepared by adding 36g of water to a dry mixture containing 6g of red phosphorus, 32.5g of inert filler and 1.Og of cornflour. 60g of potassium chlorate was added to the wet mixture and thoroughly combined.

0.5g of wallpaper paste was added to the resulting mixture and stirred until a paste-like consistency was achieved (15 -30 seconds). The resultant paste-like mixture was metered into a stainless steel cup and placed in a drying oven.

Examole 3 A primer composition was prepared by adding 36g of water to a dry mixture containing 6g of red phosphorus, 32.75g of inert filler and 0.75g of cornflour.

60g of potassium chlorate was added to the wet mixture and thoroughly combined. 0.5g of wallpaper paste was added to the resulting mixture and stirred until a paste-like consistency was achieved (15 -30 seconds). The resultant paste-like mixture was metered into a stainless steel cup and placed in a drying oven.

ExamDle 4 A primer composition was prepared by adding 36g of water to a dry mixture containing 6g of red phosphorus, 30.5g of inert filler and 3.Og of cornflour. 60g of potassium chlorate was added to the wet mixture and thoroughly combined.

0.5g of wallpaper paste was added to the resulting mixture and stirred until a * ** paste-like consistency was achieved (how long does this take -approximately?).

The resultant paste-like mixture was pressed into rimfire primer cases using a S...

small press at 30 psi with an angled punch and placed in a drying oven.

*.:.. This product was able to cycle the M16 and the G36 OK over repeated rounds of *.5 ammunition.

:.. ExamDIe5 S... * .

A primer composition was prepared by adding 36g of water to a dry mixture containing 6g of red phosphorus, 29.5g of inert filler and 4.Og of cornflour. 60g of potassium chlorate was added to the wet mixture and thoroughly combined.

0.5g of wallpaper paste was added to the resulting mixture and stirred until a paste-like consistency was achieved (15 -30 seconds}. The resultant paste-like mixture was pressed into a stainless steel cup and the cup and primer dried.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example, with reference to the accompanying figures in which; Figure 1 shows a sectional elevation through the primer for a centre fire primer cartridge.

Figure 2 shows a primer for a rimfire primer cartridge.

Figure 3 shows one example of a training cartridge embodying a piston and cylinder type recycling mechanism.

Figure 4 shows another example of a training cartridge embodying a piston and cylinder type recycling mechanism. In this embodiment, the cartridge includes primers in each of an anterior and a posterior portion, the anterior primer being operative to propel a projectile from the cartridge and assist in the recycling of the weapon.

In Figure 3, the cartridge 2 comprises a cylindrical cartridge case 4 with an in- : ** turned flange 6 at the rearward end. The forward end of the casing comprises a nose portion 8, which in this embodiment is in the form of a plug, from which sleeve 4 extends in a rearwards direction. The plug 8 has an axial bore 10. * ** * . S *e..

*. The inner surface of the sleeve and the rearward surface 12 of the plug define a piston chamber 14. A piston 16 is slidably contained within the piston chamber :.::, 14 and has a pair of outwardly extending flanges 18 at its forward end. Nested I...

.... between the flanges 18 and surrounding the piston is an O'-ring 20 to provide a seal between the forward end of the piston and the inner surface of the casing.

A pyrotechnic composition 22 is housed at the rearward end of the piston 16.

Extending from the pyrotechnic composition to the forward end of the piston is a first gas expansion chamber 24. At the head of the gas expansion chamber 24, gas channels 26 allow the flow of propellant gas from the first expansion chamber 24 into a second expansion chamber 14a (which corresponds to the expansion chamber defined in the claims appended hereto), which is defined by the space between the piston head and the rearward surface 12 of the plug.

A spigot 28 extends from the forward end of the piston and is slidably contained within the axial bore 10 of the plug. Spigot 28 is surrounded by 0-ring 30 which provides a seal with the inner surface of the axial bore 10.

In operation, the pyrotechnic composition 22 is activated by the impact of the firing pin P and the propellant gas formed by ignition of the composition expands into the first gas expansion chamber 14 and then through the gas channels 26 between the first gas expansion chamber 14 and the second expansion chamber 14a at the front of the piston. The pressure of expanding gas in the second expansion chamber forces the piston (and with it the spigot) to move rearwardly relative to the outer casing 4. Thus the piston is propelled rearwardly against the breech block B to recycle the firearm.

The extent of rearwards movement of the piston, and hence the degree of :: expansion of the cartridge casing is limited by the flanges 18 on the forward end of the piston which engages with the flange 6 on the rearward end of the casing *, 4.

As the cartridge casing expands and the piston 16 is propelled rearwardly, the :.. bullet shape presented by the spigot is withdrawn into the cartridge keeping the *", overall length of the cartridge substantially the same as a normal spent cartridge S., and thereby allowing the cartridge to be ejected in the normal way.

At least a portion of the spigot 28 remains in the bore 10 after firing. An advantage of this is that it prevents relative pivoting movement taking place between the piston and the casing as the piston moves rearwardly out of the casing, eliminating the risk of the base section of the piston from bending relative to the axis of the assembly and missing the cartridge eject mechanism of the gun.

In Figure 4 a cartridge comprises an anterior portion 1 and a posterior portion 2 the posterior portion comprising a piston 3 slideable in a cylinder 4 extending rearwardly from the anterior portion 1. The anterior portion 1 is provided with a gas passage 5 which communicates with an expansion chamber 7. The piston 3 is provided with a hollow interior 8 which connects with expansion chamber 7.

Disposed toward the posterior end of the piston 3 is a first primer 10 and in the anterior portion there is a second primer 11.

A rubber sealing ring 14 is provided between the piston 3 and cylinder 4 to prevent passage of gas to the posterior portion 2. Adjacent the rubber sealing ring 14, the piston is provided with a rim of extended circumference 15, which, when the piston is allowed to extend from the cylinder, encounters a flange 16 provided on the inner circumference of the cylinder 4 to the posterior end of the cylinder 4.

In the embodiment of Figure 4 the first primer 10 is initiated by, for example, a :.:::* firing pin to produce a volume of gas. The gas travels along the hollow interior 8 S..

.... and into expansion chamber 7. Expansion of the gas causes the piston 3 to slide * *, rearwardly within cylinder 4 towards a breech block (not shown). The piston 3 is prevented from exiting cylinder 4 by the flange and rim (16, 15) provided respectively on the inner circumference of the cylinder 4 and piston 3. The : * * shock/pressure wave created on ignition of first primer 10 initiates a second ***.

energetic response on second primer 11 located in the anterior portion 1 of the *..

cartridge. The anterior portion 1 is provided with an internal profile suitable for receiving a projectile 17. The energetic reaction produced in primer 11 propels the projectile 17 from the cartridge at high speed to create the impression of a live bullet being fired. Thus it can be seen that recycling and firing of the projectile are controlled independently by two separate energetic reactions.

It will be understood that the novel aspects of the claimed invention are in the materials used to prepare the primer cups of the invention and so are difficult to illustrate. It is to be appreciated that the invention may be incorporated in any of the illustrated embodiments of Figures 1 to 4 without departing significantly from the mechanical design thereof.

Claims

CLAIMS

1. A primer cup for a gun cartridge characterised in that the primer composition comprises phosphorus and an oxidising agent.
2. A primer cup as claimed in claim 1 wherein the primer composition also comprises one or more components selected from a gritty filler, a starch and a binding agent.
3. A primer cup as claimed in claim 1 or claim 2 wherein the primer composition according to claim 1 or claim 2, wherein the phosphorus comprises 0.25 to 10.00%, particularly 0.50 to 8.00% and especially 1.50 to 6.00% of the dry weight of the composition.
4. A primer cup as claimed in any preceding claim wherein the * ** oxidising agent of the primer composition is selected from one or more of potassium chlorate, potassium perchiorate, ammonium chlorate, ammonium perchlorate, calcium chlorate and calcium perchlorate. * S.
5. A primer cup as claimed in claim 4 wherein the oxidising agent *..

* comprises 20.00 to 99.00%, especially 60.00 to 97.00% of the dry weight :.. of the composition.
6. A primer cup according to claim 4 or claim 5, wherein the oxidising agent is potassium chlorate.
7. A primer cup according to any one of the preceding claims wherein the inert filler of the primer composition is selected from ground stone, ground glass, talc, feldspar, and silicate minerals of diatomaceous earth elements having a particle size in the range 5 to 150pm.
8. A primer cup according to claim 7, wherein the inert filler comprises 10.00 to 50.00%, preferably 25.00 to 35.00% and especially 29.5 to 33.OO% of the dry weight of the composition.
9. A primer cup according to claim 8, wherein the inert filler is ground stone.
10. A primer cup according to any one of the preceding claims, wherein the starch component of the primer composition is selected from one or more of powders derived from paper, cellulose, corn, wheat, potato, rice, maize and barley.
11. A primer cup according to claim 10, wherein the starch component is cornflour.
12. A primer cup according to claim 10 or claim 11, wherein the starch component comprises 0.025 to 10.O0%, preferably 0.75 to 5% and especially 1.00 to 4.00% by weight of the dry weight of the composition.
13. A primer cup according to any one of claims 10 to 12, wherein the ratio of the starch component to the oxidant is 1:6. I.S * S S...

*
14. A primer cup according to any one of the preceding claims, the primer composition including a binding agent selected from BAL latex binder or a wallpaper paste comprising carboxymethylcellulose and :.. sodium hydroxyethylcellulose. *..
15. A primer cup according to any one of the preceding claims, the primer composition comprising 6.00% of red phosphorus, 60.00% of potassium chlorate, 29.50 to 33.00 h of an inert filler, 0.50 to 4.0O% of cornflour and 0.5O% of wallpaper paste by dry weight of the composition.
16. A primer cup according to any one of claims 1 to 14, the primer composition comprising 2.00% of red phosphorus, 97.OO% of potassium chlorate, 0.50% of wallpaper paste and 0.50% of a BAL latex binder by dry weight of the composition.
17. A primer cup according to any preceding claim further comprising an anvil.
18. A primer cup according to any of claims 1 to 16 wherein the cup is deformed about its upper rim and is configured to be fired by impacting on the rim.
19. A method of preparing a primer cup according to any one of the preceding claims comprising the steps of a. combining water in an amount of 36% of the final weight of the dry primer composition to a mixture of phosphorus, inert filler and starch component; b. adding the oxidising agent to the wet mixture and thoroughly combining the resulting mixture of components; c. adding the binding agent to the mixture obtained from (b) : ** thereby to form a paste; and * *.* d. pressing the paste into a plurality of cups.
20. A method as claimed in claim 19 further comprising deforming the open end of the cups thereby to retain the paste in the cup.

:.:..
21. A method as claimed in claim 19 or 20 further comprising oven drying the filled cups.
22. A method as claimed in any of claims 19 to 21 wherein the cups comprise steel.
23. A gun cartridge comprising a primer cup according to any of claims 1 to 18.
24. A gun cartridge as claimed in claim 23 wherein the cartridge is of a double primer configuration and at least one of the primers comprises the said primer cup.
25. A gun cartridge as claimed in claim 24 wherein the front and rear primers have different compositions.
26. A gun cartridge as claimed in claim 24 or 25 wherein the front primer comprises 97.00% of potassium chlorate of the dry weight of the composition and no gritty filler.
27. A gun cartridge as claimed in claim 24 or 25 wherein the rear primer composition includes a gritty filler and 20.0 to 60.0% oxidant by dry weight of the composition.
28. A gun cartridge according to claim 27 wherein the oxidant is present as 40.0 to 60.0% by dry weight of the composition.
29. A gun cartridge according to claim 27 wherein the oxidant is present as 60.0% by dry weight of the composition.
30. A gun cartridge as claimed in claim 24 or 25 wherein the front primer contains a filler such that its amount and particle size result in the primer having an energy of 1.5 to 3.5 ft lbs (2.03 to 4.75 Joules) upon I...

ignition. * .. * * S

*5.* . -.
31. A gun cartridge as claimed in claim 24 wherein the rear primer S..

comprises 60.0% by weight of potassium chlorate and 29.5 to 33.0% by weight of a gritty filler. S....

"5
32. A gun cartridge as claimed in claim 24 wherein the rear primer comprises an inert filler having particle sizes in the range 60 to 120pm.

33. A gun cartridge as claimed in claim 32 wherein the inert filler comprises 10.00 to 50.00% of the dry weight of the composition, preferably 25.00 to 35.00% of the dry weight of the composition and more preferably 29.5 to
33.00% of the dry weight of the composition.

34. A gun cartridge as claimed in claim 24 or 25 wherein the rear primer composition comprises 6.00% red phosphorus, 60.00% potassium chlorate; 29.5 to 33% inert filler, 0.50 to 4.00% cornflour and 0.5% of wallpaper paste by dry weight of the composition.

35. A gun cartridge as claimed in claim 24 or 25 wherein the front the primer composition comprises 2.0O% by weight red phosphorus, 97.00% by weight potassium chlorate, O.5O% by weight of a wallpaper paste and 0.50% by weight of BAL latex binder.

36. A gun cartridge as claimed in any of claims 23 to 25 wherein the cartridge is configured for use in non-lethal applications. a * a * a... * a a... * 1 * . * a'.. a.. * . * * a.-. * . a..