WO2018083680A1

WO2018083680A1 - Cartridge case assembly and chamber

Info

Publication number: WO2018083680A1
Application number: PCT/IB2017/056942
Authority: WO
Inventors: Pieter Willem Van Niekerk
Original assignee: Pieter Willem Van Niekerk
Priority date: 2016-11-07
Filing date: 2017-11-07
Publication date: 2018-05-11

Abstract

The invention relates to a reusable cartridge case assembly [10] for a firearm cartridge, particularly for rifle cartridges that are used in long-range shooting. The cartridge case assembly [10] comprises a cylindrical shell case body [12] terminating at one end thereof in a shell case opening [18], which is characterised therein that the shell case opening [18] has an external diameter [X] which is equal to the external diameter [X] of the shell case body [12]; and a removable seal [20], which is snug-fitted into the shell case opening [18] for sealing the cylindrical shell case body [12], and including a projectile receiving aperture [22] extending through the seal [20] for receiving various calibre projectiles [24] in coaxial alignment with the shell case body [12]. The invention also extends to a firearm chamber [38] which is complimentarily configured to cooperate with the cartridge case assembly [10].

Description

CARTRIDGE CASE ASSEMBLY AND CHAMBER

INTRODUCTION

This invention relates to a novel case assembly for an ammunition cartridge. Particularly, although not exclusively, the cartridge case assembly is adapted for rifle cartridges that are used in long-range shooting. The invention also extends to a chamber which is complimentarily configured to cooperate with the cartridge case assembly. BACKGROUND TO THE INVENTION

The growing popularity of long-range shooting has prompted firearm and optics companies to develop new products that make it easier to hit a target from extreme ranges. Long-range shooting may involve target distances of as much as 1 000m or even 2000m. Long-range shooting is a sport of technical details, and if any detail is overlooked, it can - and often does - mean a miss.

Cartridge specifications are determined by several standards organizations, including SAAMI in the United States and C. I. P. in many European states. Critical cartridge specifications include neck size, bullet weight and calibre, maximum pressure, headspace, overall length, case body diameter and taper, shoulder design, rim type, etc. Generally, every characteristic of a specific cartridge type is tightly controlled and few types are interchangeable in any way. A modern cartridge (also called a round or a shell) typically comprises the following elements, namely a projectile (also called bullet or shot); a propellant (usually either smokeless powder or black powder); a case for housing the propellant and for assembling the cartridge parts; a rim, which provides an extractor on a firearm a place to grip the case to remove it from a chamber once fired; and a primer, which is a small charge of an impact-sensitive or electric-sensitive chemical mixture which ignites the propellant. The case is typically a cylinder which defines a firing chamber and which terminates at one end thereof in a conically shaped shoulder-and-neck formation which is adapted tightly to engage a projectile. In use, a firing pin strikes the primer and ignites it so that the primer compound deflagrates. A jet of burning gas from the primer ignites the propellant, creating pressure, in response to which the bullet is projected down the bore of a barrel.

Cartridge designs have to solve two primary problems. In a firearm barrel they must first form a seal with the firearm's bore. If a strong seal is not achieved, gas from the propellant charge leaks past the projectile, thus reducing efficiency and possibly accuracy. The cartridge must also engage the firearm without damaging or excessively fouling the firearm's bore, and without distorting the projectile, which will also reduce accuracy. Cartridges must be produced to a high standard, as surface imperfections can affect firing accuracy. In order to achieve concentric launching of a projectile, it is very important that a cartridge precisely fits within a firing chamber of a firearm. However, as a result of variable tolerances between manufacturing equipment of different producers a cartridge often does not precisely fit within a firing chamber, but rather rests, under the influence of gravity, at the bottom of a firing chamber, leaving a small radial aperture between the case and the firing chamber. This is referred to as a "rattle fit" and results in non-concentric launching of the projectile, the negative effect of which increases with target distance. During firing, gases from the burning powder pressurize and expand the case to seal it against the chamber wall, slightly deforming the case in the process. This is called "fire forming". After the bullet leaves the barrel, the chamber pressure drops to atmospheric pressure. The case, which had been elastically expanded by chamber pressure, contracts slightly, which eases removal of the case from the chamber.

Brass is a commonly used case material because it is resistant to corrosion. A brass case head can be work-hardened to withstand the high pressures of cartridges, and allow for manipulation via extraction and ejection without tearing the metal. A brass case typically has a hardness of 10 Rockwell. The neck and body portion of a brass case is easily annealed to make the case ductile enough to allow reforming so that it can be reloaded several times. However, through multiple usage and fire-forming, a brass case undergoes such work-hardening that it becomes very difficult, if not impossible, to anneal for re-use. In such an event, the case requires special treatment to increase ductility to allow further re-forming and re-use. A cartridge case is typically either extruded or drawn from a copper or brass alloy sheet which uses tensile strength of the alloy material to either push or pull it through a die. This limits the amount of change which can be performed in one step, so multiple stages are usually needed to form the case. As a result of the manufacturing process employed, it remains a technical challenge to produce high quality cartridge cases by overcoming defects that are commonly encountered in extrusion processes. Surface lines may occur on the surface of the extruded case. This depends heavily on the quality of the die production and how well the die is maintained, as some residues of the material extruded can stick to the die surface and produce the embossed lines. In worse circumstances, surface cracking may occur when the surface of an extruded case splits. This is typically caused when the extrusion temperature, friction, or speed is too high. It can also happen at lower temperatures if the extruded product temporarily sticks to the die. A rifle chamber and barrel are typically manufactured as a single unit. Through use, the barrel is subjected to wear, predominantly occurring in the so-called barrel throat, which is the end of a barrel bore closest to the chamber. Once the barrel is worn out, the barrel and chamber need to be replaced in order to maintain accurate firing. A barrel bore includes rifling, which consists of helical grooves and lands in the barrel that imparts a spin to a projectile around its longitudinal axis. This spin serves gyroscopically to stabilize the projectile, improving its aerodynamic stability and accuracy. Rifling is often described by its twist rate, which indicates the distance the rifling takes to complete one full revolution. A shorter distance indicates a "faster" twist, meaning that for a given velocity the projectile will be rotating at a higher spin rate. It will be appreciated that producing a barrel and accurate bore rifling for each calibre is a time-consuming and highly technical process, requiring skilled artisans and resulting in significant costs, particularly in high end guns and rifles, such as those used in long range shooting. However, it often happens that a barrel requires replacement, but the chamber is still functional. Replacement of both the barrel and chamber not only wastes costs, but may also increase replacement times as a result of the technical input required to produce high end barrels.

It is accordingly an object of the present invention to produce a novel cartridge case that will overcome, or at least minimize, some of the disadvantages associated with prior art cases.

It is a further object of the present invention to provide a chamber which is adapted to cooperate with the cartridge case.

SUMMARY OF THE INVENTION

According to the invention there is provided a reusable cartridge case assembly for a firearm cartridge, the cartridge case assembly comprising - a cylindrical shell case body terminating at one end thereof in a rim, which is dimensioned to accommodate a percussion cap; and terminating at the opposite open end thereof in a shell case opening which is characterised therein that the shell case opening has an external dimeter which is equal to the external diameter of the shell case body; and a removable seal which is snug-fitted into the shell case opening for sealing the cylindrical shell case, the removable seal including a projectile receiving aperture extending through the seal coaxially with the shell case body and dimensioned for receiving various calibre projectiles in coaxial alignment with the shell case body.

The shell case body may be a high tensile steel case having a hardness of approximately 50 Rockwell.

The shell case body may include an internal wall surface and an external wall surface, with the internal wall surface including a step formation approximate the shell case opening which increases the internal diameter of the shell case body approximate the shall case opening for receiving the removable seal. In this embodiment of the invention the seal may be seated and pressed tightly against the step formation of the shell case upon loading of the cartridge. In an alternative embodiment of the invention and depending on seal diameter, the shell case body may include a step formation within the internal wall surface approximate the shell case opening which decreases the internal diameter of the shell case body approximate the shell case opening.

The removable seal may be a cylindrical metal seal which is configured to slide through the shell case opening and partially extend into the shell case body such that the seal radially presses tightly against the internal wall surface of the shall case body for preventing gas from a propellant charge from leaking past a projectile during firing. In one embodiment of the invention, the removable seal may be a labyrinth seal including at least one external groove and a complimentarily configured O-ring locatable in the groove for pressing against the internal wall surface of the shell case body. It will be appreciated that the labyrinth seal may include any number of external grooves and complimentarily configured O-rings. Once in position, the seal may be arranged flush with the shell case opening. In one embodiment of the invention the projectile receiving aperture extending through the cylindrical seal may terminate at one end thereof in an outwardly flaring forging cone. In particular, the forging cone is configured at an end of the seal which extends into the shell case body. The forging cone may have an angle in the order of 40° relative to the longitudinal axis of the seal, although this angle is variable depending on projectile calibre.

The seal may be manufactured from a number of alloys, including brass, aluminium, steel or beryllium containing alloys. Both the cylindrical shell case body and the removable seal are characterised therein that they are manufactured through computer pneumatic control turning. Through this process, the applicant is able more accurately to control and accurately repeat production parameters of the shell case body, whilst simultaneously overcoming the technical challenges associated with extrusion techniques.

The cartridge case assembly is characterised therein that it is not materially deformable during firing, is reusable and is not dependant on fire forming or work hardening for increasing performance or projectile alignment. The cartridge case assembly is also characterised therein that it can easily accommodate a wide range of projectile calibres and may easily be modified from one calibre to the next by replacing a removable seal having a projectile receiving aperture of one diameter, with a seal having a projectile receiving aperture of a larger or smaller diameter.

The shell case body typically has a length in the order of 51 mm and a diameter in the order of 18mm, while the seal has a length in the order of 13mm, although it will be appreciated that these dimensions will vary for larger or smaller calibres.

According to a second aspect of the invention there is provided a firearm cartridge including the cartridge case assembly as hereinbefore defined.

According to a third aspect of the invention there is provided a firearm chamber suitable for receiving the cartridge case assembly of the invention, the firearm chamber being characterised therein that it is disconnectably connected to a barrel of a firearm, the chamber having two opposite ends and comprising a cartridge receiving chamber approximate one end of the chamber; and barrel engaging means approximate an opposite end of the chamber.

The chamber may include a chamber body and an internal bore extending through the chamber body, wherein the internal bore is divided into the cartridge receiving chamber approximate the one end of the firearm chamber; and a barrel receiving chamber approximate an opposite end of the firearm chamber, the barrel receiving chamber being dimensioned for receiving at least a throat end of a barrel therein. The barrel receiving chamber may include circumferentially positioned engaging means which are adapted tightly to engage complimentarily configured engaging means on the barrel. In one embodiment of the invention, the barrel receiving chamber may include a circumferential screw thread adapted tightly to engage a complimentarily configured screw thread on an external surface of the barrel. The barrel receiving chamber may have an increased internal diameter compared to the internal diameter of the cartridge receiving chamber. The cartridge receiving chamber may terminate in a shoulder formation where it borders the barrel receiving chamber for positioning a cartridge during loading of the firearm. In particular, the arrangement may be such that when a cartridge, comprising the cartridge case assembly of the invention, is loaded in the cartridge receiving chamber, the shell case body and seal are pressed tightly against the shoulder formation, while a projectile extending through the seal is positioned in a bore of the barrel.

SPECIFIC EMBODIMENT OF THE INVENTION Without limiting the scope thereof, the invention will now further be described by way of examples only and with reference to the accompanying drawings in which -

FIGURE 1 is a perspective view of a cartridge case assembly according to a first embodiment of the invention in an assembled configuration and sectioned along the longitudinal axis [Q] of the cartridge case assembly, illustrating positioning of a projectile in the cartridge case assembly;

FIGURE 2 is an exploded, longitudinally sectioned view of the cartridge case assembly of Figure 1 ;

FIGURE 3 is an exploded, longitudinally sectioned view of a cartridge case assembly according to the first embodiment invention and a typical prior art chamber and barrel, illustrating positioning of the cartridge case assembly within the chamber;

FIGURE 4 is an assembled view of Figure 3;

FIGURE 5 is an exploded, longitudinally sectioned view of a cartridge case assembly according to the first embodiment of the invention and a firearm chamber according to the invention, illustrating positioning of the cartridge case assembly in the new firearm chamber and connection of the new firearm chamber with a prior art barrel;

FIGURE 6 is an assembled, longitudinally sectioned view of Figure 5;

FIGURE 7 is an exploded, longitudinally sectioned view of the cartridge case assembly according to a second embodiment of the invention;

FIGURE 8 is an exploded, longitudinally sectioned view of the cartridge case assembly according to the second embodiment invention and a prior art chamber and barrel, illustrating positioning of the cartridge case assembly within the chamber;

FIGURE 9 is an assembled, longitudinally sectioned view of a cartridge case assembly according to the second embodiment of the invention and a firearm chamber according to a second embodiment of the invention, illustrating positioning of the cartridge case assembly in the new firearm chamber and connection of the new firearm chamber with a prior art barrel;

FIGURE 10 is an enlarged view [A] of the cartridge case assembly and firearm chamber of Figure 9; and

FIGURE 11 is an assembled, longitudinally sectioned view of a rifle, illustrating straight feeding of a round.

A reusable cartridge case assembly for a firearm cartridge according to the invention is designated by reference numeral [10]. The cartridge case assembly [10] comprises a cylindrical shell case body [1 2] terminating at one end thereof in a rim [14], which is dimensioned to accommodate a percussion cap [16]; and terminating at the opposite open end thereof in a shell case opening [1 8]. The shell case opening [1 8] is characterised therein that it has an external dimeter [X] which is equal to the external diameter [X] of the shell case body [12].

The cartridge case assembly [10] also comprises a removable seal [20] which is snug- fitted into the shell case opening [18] for sealing the cylindrical shell case body [12]. The removable seal [20] includes a projectile receiving aperture [22] extending through the seal [20] coaxially with the shell case body [12] and dimensioned for receiving various calibre projectiles [24] in coaxial alignment with the shell case body [1 2].

The shell case body [1 2] includes an internal wall surface [26] and an external wall surface [28], with the internal wall surface [26] including a step formation [30] approximate the shell case opening [18] which increases the internal diameter [Y] of the shell case body [12] approximate the shell case opening [18] compared to the internal diameter [Z] of the remaining shell case body [1 2], for receiving the removable seal [20]. In this embodiment of the invention the seal [20] is seated and pressed tightly against the step formation [30] of the shell case body [12] upon loading of a cartridge.

The removable seal [20] is a cylindrical metal seal [20] which is configured to slide through the shell case opening [18] and at least partially extend into the shell case body [12] such that the seal [20] radially presses tightly against the internal wall surface [26] of the shall case body [1 2]. In the Figure 2 embodiment of the invention, the removable seal [20] is a labyrinth seal [20] including two peripheral grooves [32] and complimentarily configured O-rings [34] locatable in the grooves [32] for pressing against the internal wall surface [26] of the shell case body [12]. Once the seal [20] is in position in the shell case body [12], the seal [20] is arranged flush with the shell case opening [1 8].

In this embodiment of the invention the projectile receiving aperture [22] extending through the cylindrical seal [20] terminates at one end thereof in an outwardly flaring forging cone [36]. In particular, the forging cone [36] is configured at an end of the seal [20] which extends into the shell case body [12]. The forging cone [36] has an angle in the order of 40° relative to the longitudinal axis [Q] of the seal [20] and the shell case body [12].

The cartridge case assembly [10] is characterised therein that it can easily accommodate a wide range of projectile [24] calibres and can easily be modified from one calibre to the next by replacing a removable seal [20] having a projectile receiving aperture [22] of one diameter, with a seal [20] having a projectile receiving aperture [22] of a larger or smaller diameter.

The invention also includes a firearm chamber [38] suitable for receiving the cartridge case assembly [10] of the invention, the firearm chamber [38] being characterised therein that it is disconnectably connected to a barrel [40] of a firearm, the chamber [38] having two opposite ends and comprising a cartridge receiving chamber [42] approximate one end of the chamber [38]; and barrel engaging means [44] approximate an opposite end of the chamber [38].

The chamber [38] includes a chamber body [46] and an internal bore [48] extending through the chamber body [46], wherein the internal bore [48] is divided into the cartridge receiving chamber [42] approximate the one end of the firearm chamber [38]; and a barrel receiving chamber [44] approximate an opposite end of the firearm chamber [38]. The barrel receiving chamber [44] is dimensioned for receiving at least a throat end [50] of a barrel [40] therein.

The barrel receiving chamber [44] includes circumferentially positioned engaging means [52] which are adapted tightly to engage complimentarily configured engaging means [54] on the barrel [40]. In the illustrated embodiment of the invention, the barrel receiving chamber [44] includes a circumferential screw thread [52] adapted tightly to engage a complimentarily configured screw thread [54] on an external surface of the barrel [40]. The barrel receiving chamber [44] has an increased internal diameter compared to the internal diameter of the cartridge receiving chamber [42]. The cartridge receiving chamber [42] terminates in a shoulder formation [56] where it borders the barrel receiving chamber [44] for positioning a cartridge during loading of the firearm. In particular, the arrangement is such that when a cartridge, comprising the cartridge case assembly [1 0] of the invention, is loaded into the cartridge receiving chamber [42], the shell case body [12] and seal [20] are tightly pressed against the shoulder formation [56], while a projectile [24] extending through the seal [20] is positioned in a bore [58] of the barrel [40]. The shoulder formation [56] may include a removable hardened steel plate. In the cartridge case assembly [10] of Figure 7, the removable seal [20], which is snug- fitted into the shell case opening [18] for sealing the cylindrical shell case body [1 2], is also a labyrinth seal [20] including two peripheral grooves [32] and two complimentarily configured O-rings [34] locatable in the grooves [32] for pressing against the internal wall surface [26] of the shell case body [12]. However, in this embodiment of the invention, the seal [20] includes a radially outwardly extending wing [60]. The wing [60] includes a third groove [32] and complimentarily configured third O-ring [34] locatable in the groove [32] of the wing [60]. In this embodiment, the seal [20] extends only partially into the shell case body [12], while the wing [60] rests atop the shell case opening [1 8]. Once the seal [20] is in position in the shell case body [12], seated and pressed tightly against the step formation [30] of the shell case body [12], the seal [20] partially protrudes out of the shell case opening [18].

In this embodiment, and as illustrated in Figures 9 and 10, the cartridge receiving chamber [42] terminates in a tapered shoulder formation [56] which is complimentarily configured to engage and seal against the radially outwardly extending wing [60] of the removable seal [20] of Figure 7. In particular, the arrangement is such that when a cartridge, comprising the cartridge case assembly [10] of Figure 7, is loaded into the cartridge receiving chamber [42], the shell case body [12] and wing [60] of the seal [20] are tightly pressed against the tapered shoulder formation [56], while a projectile [24] extending through the seal [20] is positioned in a bore [58] of the barrel [40].

The cartridge case assembly of the invention was designed with the objective in mind to have a stronger case with better concentricity of a loaded round. The outside diameter was initially designed to be the same as the diameter of a normal Remington 700 action bolt. This can be done for almost any bolt as required.

Figure 1 1 illustrates straight feeding of a loaded round [64], which is ready to be fed into a chamber [42]. With conventional ammunition, the case diameter is smaller than the bolt [62] by up to 6mm. This is done because the brass from which a cartridge case is manufactured must withstand high pressures and a so-called rebated rim may cause the case to fail. With the rebated rim design of the cartridge case assembly [10] of the invention, it is possible to have the bolt [62] at the same size than the case diameter without any risk of failure. With normal ammunition the round [64] must be fed from the top of a magazine onto a feed ramp and then up into the chamber [42] at an angle. This may cause damage to the front (Meplat) of the projectile [24]. The case may also bend when it is fed into the chamber. However, with a special design of the magazine [68], it is possible to feed the round [64] straight into the chamber [42]. The bolt [62], which has locking lugs at the rear and is cylindrical in front, can be used to feed the round [64] straight without any feed ramp or loading at any angle. This results in no damage to the loaded round [64]. This method of feeding can be used for bolt action, semi auto and full auto weapons. The straight feeding will also be more reliable than conventional feeding, as most stoppages occur when the round [64] is fed at an angle into the chamber [42].

It will be appreciated that other embodiments of the invention are possible without departing from the spirit or scope of the invention as defined in the claims.

Claims

1 . A reusable cartridge case assembly [10] for a firearm cartridge, the cartridge case assembly [10] comprising - a cylindrical shell case body [1 2] terminating at one end thereof in a rim [14], which is dimensioned to accommodate a percussion cap [1 6]; and terminating at the opposite open end thereof in a shell case opening [18], which is characterised therein that the shell case opening [18] has an external diameter [X] which is equal to the external diameter [X] of the shell case body [12]; and

a removable seal [20], which is snug-fitted into the shell case opening [18] for sealing the cylindrical shell case body [1 2], the removable seal [20] including a projectile receiving aperture [22] extending through the seal [20] coaxially with the shell case body [1 2] and dimensioned for receiving various calibre projectiles [24] in coaxial alignment with the shell case body [12].

2. The cartridge case assembly [10] according to claim 1 wherein the shell case body [12] is a high tensile steel case having a hardness of approximately 50 Rockwell.

3. The cartridge case assembly [10] according to claim 1 wherein the shell case body [12] includes an internal wall surface [26] and an external wall surface [28], with the internal wall surface [26] including a step formation [30] approximate the shell case opening [18] which increases the internal diameter [Y] of the shell case body [1 2] approximate the shall case opening for receiving the removable seal [20].

The cartridge case assembly [10] according to claim 3 wherein the seal [20] is seated and pressed tightly against the step formation [30] of the shell case body [12] upon loading of the cartridge.

The cartridge case assembly [10] according to claim 1 wherein the shell case body [12] includes an internal wall surface [26] and an external wall surface [28], with the internal wall surface [26] including a step formation [30] approximate the shell case opening [1 8] which decreases the internal diameter [Y] of the shell case body [12] approximate the shell case opening [18].

The cartridge case assembly [10] according to claim 1 wherein the removable seal [20] is a cylindrical metal seal [20] which is configured to slide through the shell case opening [1 8] and at least partially extend into the shell case body [12] such that the seal [20] radially presses tightly against an internal wall surface [26] of the shall case body [12] for preventing gas from a propellant charge from leaking past a projectile [24] during firing.

The cartridge case assembly [10] according to claim 6 wherein the removable seal [20] is a labyrinth seal, including at least one external groove [32] and a complimentarily configured O-ring [34] locatable in the groove [32] for pressing against the internal wall surface [26] of the shell case body [12].

8. The cartridge case assembly [10] according to claim 7 wherein the labyrinth seal [20] includes a number of external grooves [32] and complimentarily configured O-rings [34].

9. The cartridge case assembly [10] according to any one of claims 7 or 8, wherein, once in position, the seal [20] is arranged flush with the shell case opening [18].

10. The cartridge case assembly [10] according to any one of claims 7 or 8, wherein the seal [20] includes a radially outwardly extending wing [60], the arrangement being such that the seal [20] extends only partially into the shell case body [1 2], while the wing [60] rests atop the shell case opening [18], such that once the seal [20] is in position within the shell case body [12], seated and pressed tightly against the step formation [30] of the shell case body [12], the seal [20] partially protrudes out of the shell case opening [18].

1 1 . The cartridge case assembly [10] according to claim 1 wherein the projectile receiving aperture [22] extending through the cylindrical seal [20] terminates at one end thereof in an outwardly flaring forging cone [36].

12. The cartridge case assembly [10] according to claim 1 1 wherein the forging cone [36] is configured at an end of the seal [20] which extends into the shell case body [12] and has an angle in the order of 40° relative to the longitudinal axis [Q] of the seal [20].

13. The cartridge case assembly [10] according to claim 1 wherein the seal [20] is manufactured from a number of alloys, including brass, aluminium or beryllium containing alloys.

14. The cartridge case assembly [1 0] according to claim 1 wherein the cylindrical shell case body [12] and the removable seal [20] are characterised therein that they are manufactured through computer pneumatic control turning.

15. The cartridge case assembly [10] according to claim 1 wherein the cartridge case assembly [10] is characterised therein that it is not materially deformable during firing, is reusable and is not dependent on fire forming or work hardening for increasing performance or projectile alignment.

16. The cartridge case assembly [10] according to claim 1 wherein the cartridge case assembly [10] is also characterised therein that it can easily accommodate a wide range of projectile [24] calibres and is easily modified from one calibre to the next by replacing a removable seal [20] having a projectile receiving aperture [22] of one diameter, with a seal [20] having a projectile receiving aperture [22] of a larger or smaller diameter.

17. A firearm cartridge including the cartridge case assembly [10] according to any one of Claims 1 to 1 6.

18. A firearm chamber [38] suitable for receiving the cartridge case assembly [10] according to any one of Claims 1 to 16, the firearm chamber [38] being characterised therein that it is disconnectably connected to a barrel [40] of a firearm, the chamber [38] having two opposite ends and comprising a cartridge receiving chamber [42] approximate one end of the chamber [38]; and barrel engaging means [44] approximate an opposite end of the chamber [38].

The firearm chamber [38] according to claim 18 wherein the chamber [38] includes a chamber body [46] and an internal bore [48] extending through the chamber body [46], wherein the internal bore [48] is divided into the cartridge receiving chamber [42] approximate the one end of the firearm chamber [38]; and a barrel receiving chamber [44] approximate an opposite end of the firearm chamber [38], the barrel receiving chamber [44] being dimensioned for receiving at least a throat end [50] of a barrel [40] therein.

The firearm chamber [38] according to claim 1 9 wherein the barrel receiving chamber [44] includes circumferentially positioned engaging means [52], which are adapted tightly to engage complimentarily configured engaging means [54] on the barrel [40].

The firearm chamber [38] according to claim 20 wherein the barrel receiving chamber [44] includes a circumferential screw thread [52] adapted tightly to engage a complimentarily configured screw thread [54] on an external surface of the barrel [40].

22. The firearm chamber [38] according to claim 1 9 wherein the barrel receiving chamber [44] has an increased internal diameter compared to the internal diameter of the cartridge receiving chamber [42].

23. The firearm chamber [38] according to claim 19 wherein the cartridge receiving chamber [42] terminates in a shoulder formation [56] where it borders the barrel receiving chamber [44] for positioning a cartridge during loading of the firearm, the arrangement being such that when a cartridge, comprising the cartridge case assembly [10] of any one of Claims 1 to 16, is loaded into the cartridge receiving chamber [42], the shell case body [12] and seal [20] are pressed tightly against the shoulder formation [56], while a projectile [24] extending through the seal [20] is positioned in a bore [58] of the barrel [40].

24. The firearm chamber [38] according to claim 23 wherein the cartridge receiving chamber [42] terminates in a tapered shoulder formation [56], which is complimentarily configured to engage and seal against the radially outwardly extending wing [60] of the removable seal [20] of Claim 10.