WO2004070308A2

WO2004070308A2 - Firearm with supplementary firing chamber

Info

Publication number: WO2004070308A2
Application number: PCT/IB2004/000540
Authority: WO
Inventors: Salvatore Tedde
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-02-10
Filing date: 2004-02-10
Publication date: 2004-08-19
Anticipated expiration: 2005-08-10
Also published as: ITRM20030054A1; WO2004070308A3; ITRM20030054A0

Abstract

Firearm for shooting projectiles by means of the synergic effect of a propulsive explosion produced by a principal cartridge (7) and of a second explosion, which takes place in a time immediately subsequent to the previous one, and which is produced by a supplementary blank cartridge (4) provided in a supplementary firing chamber (2) communicating with the barrel (1) of the firearm by means of connection holes (3). The second explosion is primed automatically by the action of combustion gases produced by the principal cartridge (7).

Description

FIREARM WITH SUPPLEMENTARY FIRING CHAMBER Field of the invention

The present invention relates to the firearms field and more specifically to an improvement relative to firearms of any type, such as heavy artillery, rifles and carabines, in order to increase the values of gaseous pressure produced due to combustion of the propelling charge. In this way, a drastic increase is obtained in the velocity at which the projectile leaves the barrel of the weapon, as this speed is proportional to the magnitude and duration of the pressure producing the propulsive thrust on the projectile. STATE OF THE ART.

Known firearms are commonly characterized by the use of ammunition composed of cartridges comprising a casing containing gunpowder and closed at the front by the projectile. To date, the development of ammunition and firearms has reached such levels that, although desirable, any further increase in their ballistic performance is progressively more arduous and difficult to achieve.

As is known, striking of the primer of a cartridge initiates combustion of the propelling charge contained in it, thus producing combustion gases. As these gases cannot expand freely outside, they produce an increase in the pressure around the charge that is still to be burned, thus causing the fundamental and well- known phenomenon that transforms the combustion reaction of the powder into an actual explosion.

It must be noted that this increase in pressure drastically accelerates combustion, resulting in the production of more gas that concurs in further increasing the pressure with a chain reaction. The pressure values that are reached are in the order of a few thousand atmospheres until consumption of the gunpowder.

The highly compressed gases exert their propulsive action by releasing the projectile from the neck of the casing and accelerating it along the barrel of the firearm.

It must be noted that much of the pressure is used to overcome the initial inertia of the mass of the projectile and to overcome the frictions resulting from its travel through the riflings of the barrel. Following this, the projectile reaches maximum velocity with helical motion and the pressure imposed by thrust to the projectile, after reaching its maximum peak value, starts to drop mainly due to the decrease in the production of gas. All this takes place in the first centimeters of travel of the bullet.

Although the phenomenon described above is almost instantaneous, it requires a certain amount of time (albeit small), and can therefore be efficaciously optimized. To do this it is necessary to increase the rate at which combustion gases are formed as a function of the linear increase of the volume available for them (determined by the space between the bottom of the casing and the base of the bullet) due to movement of the projectile along the barrel. Summary of the invention Therefore, the main object of the present invention is to extend the duration of the action of the pressure that thrusts the projectile traveling along the barrel of the firearm, in order to obtain increased muzzle velocity, increased range, a considerable increase in precision on the target, and a tremendous increase in kinetic energy (proportional to the squared velocity) and in the resulting impact power.

Therefore, the invention is particularly suitable for cannons of any size and for rifles which, however, as shall become more apparent below, is preferably of the manually loaded type, that is neither automatic nor semi-automatic. These objects have been reached, according to the invention, by a firearm with the features of claim 1.

The firearm is provided with a supplementary device, the auxiliary chamber, the use of which allows a synergic effect to be obtained between the customary first propulsive explosion and at least a second propulsive explosion that takes place subsequently, although very close in time, to the first one. In particular, according to the invention, the first explosion is produced as usual by the principal cartridge carrying the projectile, while the subsequent explosion is produced by a supplementary cartridge without a projectile, that is a "blank" cartridge, which is located in the supplementary or auxiliary firing chamber communicating with the barrel of the firearm, and which is primed automatically through the action of combustion gases produced by the principal cartridge.

According to another aspect of the invention, the objects were obtained by means of a process to shoot a projectile implemented by means of a firearm as described previously, having the features of claim 12. According to a further aspect of the invention the objects were obtained by means of a firing cartridge utilizable by the firearm as described above and having the features of claim 14.

Brief description of the figures The invention shall be better understood with the help of the following detailed description and with reference to the attached figures showing preferred embodiments, by way of non-limiting examples.

Figure 1 shows a sectional view of a portion of firearm barrel and of the relative supplementary firing chamber in a first embodiment of the invention; Figure 2A is a cross section of the barrel along the plane A-A in Figure 1 ;

Figure 2B is a side view of the blanking screw of the supplementary -firing chamber;

Figure 3 schematically shows the projectile, in the phase immediately after the explosion of its cartridge, while it is traveling the initial stretch of the barrel under the thrust of the combustion gases;

Figure 4 schematically shows the phase in which the combustion gases enter the supplementary firing chamber and abruptly push the blank cartridge backwards;

Figure 5 is a diagram showing the trend of the propulsion pressures of the projectile while it is traveling along the barrel of the firearm; Figure 6 shows a second embodiment of the invention, provided with two supplementary firing chambers;

Figure 7 represents a section in an axial plane of a cartridge conforming to the invention before use;

Figure 7a represents a side view of a detail of the cartridge of Figure 7; Figure 8 represents a section in an axial plane of the cartridge of Figure 7 after use;

Figure 9 represents a section in an axial plane of the cartridge of Figure 7 in a phase of pre-assembly;

Figure 9a represents a front view of the cartridge of Figure 9. Detailed description of preferred embodiments

With reference to the figures described above, the firearm of the invention comprises at least one supplementary firing chamber 2, which communicates with the bore of the barrel 1 of the firearm by means of at least a few communication holes.

In a first embodiment of the firearm, shown in Figures 1 to 4, it comprises a single supplementary firing chamber and the barrel 1 of the firearm is positioned side by side with a supplementary firing chamber 2, which is preferably disposed with its axis parallel, or slightly inclined, in relation to the longitudinal axis of the barrel and communicates with said barrel by means of one or more holes 3 provided at its front end. The rifling of the bore of the barrel 1 is indicated with the reference 1b. According to the invention, the holes 3 are facing the inside of the barrel of the firearm, in an area located below the principal firing chamber, so that the bullet transits in the point in which the holes 3 are located after having traveled along a short stretch of the barrel 1, so that a small part of the gases produced by combustion of a principal cartridge 7, provided with projectile, enters the second firing chamber 2 with pressure values that are still extremely high. In the example shown, the supplementary firing chamber 2 is fixed integrally with the barrel 1 by means of a strong weld 1a, or with other appropriate fixing means. As shown by the aforesaid figures, the supplementary or auxiliary firing chamber 2 is preferably disposed in the area in front of the principal firing chamber, that is towards the muzzle of the barrel 1. The distal area of the supplementary firing chamber 2, that is the area opposite the end communicating with the barrel 1 through the holes 3, is provided with a thread 2a screwed into which is a blanking screw 5, which is provided in the part inside the chamber 2 with a specific fixed firing pin 5a, integral with the screw. The supplementary cartridge 4, without projectile, is inserted before the shot in this secondary firing chamber 2 and is closed by means of said blanking screw 5, which for this purpose is provided with a knurled rear area or drum to allow the user to tighten or loosen it manually from the distal thread 2a of the secondary firing chamber 2, without any tools being required. Alternatively, if necessary the screw may be tightened or loosened with suitable means provided for the purpose. Other closing means that can be operated more quickly may opportunely be provided to close the supplementary chamber 2, i.e. bayonet or other types of closing systems. For the reasons stated above, when the first cartridge 7 is shot, the first propulsion sequence starts, during which the pressurized gases produced by this explosion, indicated with the reference 8 in Figure 3, accelerate the relative projectile in the usual way. At this point, according to the invention, as soon as the bullet moves beyond the communication holes 3 between the barrel 1 and the supplementary firing chamber 2, a quota (indicated with the reference 10 in Figure 4) of the propulsion gases at extremely high pressure produced by the primary cartridge 7 enters said supplementary firing chamber 2 determining an abrupt increase of the pressure inside it. This causes the secondary blank cartridge 4 to undergo a sudden backward movement towards the firing pin 5a integral with the blanking screw 5, which causes ignition of the explosive charge inside it. According to the invention, explosion of the second cartridge 4 causes a further and extremely strong increase in pressure which is sent back, by means of the communication holes 3, into the area of the barrel 1 behind the projectile, which is hence thrust by the pressure of the gases produced by two distinct sequential propulsive explosions.

It must be pointed out that, according to a peculiar characteristic of the invention, the velocity with which combustion of the second charge takes place is twice the speed of the charge in the primary cartridge 7, the propellant contained in the supplementary cartridge 4, in fact, is ignited starting from the two ends of the cartridge: the first ignition is caused, as is known, by the blanking screw 5 striking the primer positioned at the base of the charge, while the second ignition is produced, essentially simultaneously to the first, by the incandescent gases 10 present in the area in front of the cartridge 4, coming into contact with the charge of said cartridge.

Therefore, the rate of pressure that takes place behind the projectile, shown in the graph in Figure 5, determines a tremendous increase in the muzzle velocity and in the corresponding impact energy on the target. The graph mentioned above shows that, advantageously, the supercharge energy does not cause any increase in pressure structurally damaging for the firearm, as said energy acts on the projectile already moving at high speed, that is to say when it has already moved beyond the most critical phases of propulsion, which are initial acceleration of the frictions resulting from its travel through the helical riflings 1b of the barrel 1. Considering the graph of the pressures along the barrel 1, the curve 13 of the supercharge pressure does not overlap the curve 12 of the primary pressure, but extends consecutively to it. In other words, the propulsive energy produced by explosion of the supplementary cartridge 4 maintains the pressure of. the gases that thrust the projectile close to its maximum value essentially constantly for almost the entire travel of the bullet along the barrel 1 of the firearm. With a view to this, it is useful to observe that the supplementary cartridge 4, containing a large quantity and high quality of gunpowder, is capable of producing large increases in pressure energy. In the light of the above, according to the invention it is advantageously possible to combine the effect of gunpowders having different characteristics to optimize the efficacy of the weapon using them, for example by combining the use of slow burning propellants for the primary cartridge 7 with other fast burning propellants for the supplementary cartridge 4, or vice versa, etc.. A second embodiment of the invention, shown in Figure 6, shows the barrel 1 of a firearm provided with two supplementary firing chambers 2 positioned side by side and converging on the single barrel 1, which act simultaneously with their supplementary propulsive action. Finally, it is also possible to provide, in particular cases, two supplementary firing chambers 2 in tandem or on either side of the barrel, both communicating with a single barrel 1 at different distances from the primary cartridge 7, which act sequentially (not shown in the figures). In order to increase the efficacy of the effect caused by the auxiliary or supplementary cartridge, a cartridge is produced with the characteristics described below and shown in Figures 7 to 9a. The auxiliary blank cartridge 4a has optimal performance with respect to known blank cartridges. It has a cylindrically shaped body or casing closed at a first end, which forms the bottom, and a capsule 9 which forms the apex at the second end. The capsule has a closure 9a in the shape of a star, viewed from the front. This closure 9a is preferably made of plastic or metal material. The embodiment with folds and stress raisers facilitates its tearing or opening at the moment in which the propellant 15 explodes. The capsule 9 is fitted during assembly to the mouth of the casing 4, i.e. by clamping, or with any appropriate fixing means which in any case allows limited sliding through the action of strong pressure exerted on it. Advantageously, a raised rim 4c is produced inside the casing at a specific distance from the second end; this may be a step or abutment, which acts as a stop for the capsule 9. Along the circumference of the step 4c, between the step 4c and the base of the capsule 9, a priming explosive mixture is disposed, preferably in the shape of a ring . Moreover, disposed in a known way in the bottom of the casing is a priming capsule 14.

The blank cartridge 4a encases a specific quantity of propellant 5, gunpowder of a known type. The operating mode of the cartridge 4a is now described. The cartridge 4a, is inserted during the loading procedure of the firearm into the auxiliary firing chamber 2 previously blanked by the screw 5 or by another appropriate mechanism. When the primary cartridge 7 is shot by activating a firing pin or another device pre-established for this purpose, pressurized gases are produced by the gunpowder contained in the primary cartridge 7. These gases, at high pressure, accelerate the projectile in the usual way inside the firing chamber of the barrel 1 and it moves at high speed along the barrel towards the muzzle. When the projectile passes beyond the communication holes 3 between the barrel 1 and the auxiliary firing chamber 2, a quota of the propulsion gases at extremely high pressure enters the firing chamber 2 determining a sudden increase in the pressure inside it.

The action of this pressure causes the cartridge 4a to undergo violent backward movement towards the firing pin 5a, which is integral with the blanking screw. T ie impact of the firing pin 5a against the primer capsule 14, automatically causes ignition of the explosive charge 15 inside the cartridge 4a. Simultaneously, the same pressure also provides a violent thrust to the capsule 9 that changes into a relative translatory movement between the body of the casing and the capsule. This second movement causes the priming explosive mixture disposed in the shape of a ring to be pressed against the stepped edge 4c. Priming of this ring causes ignition of the propellant in the surrounding area, which catches fire. In this way the propellant 15 is ignited starting from the two ends of the cartridge 4a. As a result of this, the velocity at which the combustion process takes place increases with respect to the velocity of the primary charge 7. As is known, according to the principles governing internal ballistics in firearms, the shorter the combustion time of the propellant is, the greater the velocity of the gaseous output acting on the projectile will be. According to the principal characteristic of the invention, explosion of the auxiliary cartridge therefore produces a further and extremely strong increase in pressure, corresponding to a supercharge, which after having violently opened the capsule 9b, bursts through the communication holes 3, into the area of the barrel 1 behind the projectile, which is thus further accelerated by the pressure of the gases produced by the two distinct sequential propulsive explosions. The cartridge 4a, as it appears after the shot, is represented in Figure 8. Here it can be seen that the capsule 9b is open, the ring 11 of priming explosive has disappeared and the propellant 15 has completely disappeared from the inside of the cartridge 4a. In this way the projectile receives an impulse that is extremely strong, resulting from the sum of several impulses, with a corresponding increase in kinetic energy with a greater impact to that of known firearms.

It is still possible to use the firearm according to the invention employing only the primary cartridges 7, ensuring that the supplementary firing chamber(s) 2 are closed by the relative blanking screws 5. This makes the use of these firearms extremely versatile.

Claims

1. Firearm comprising a shooting barrel (1), defining an internal firing chamber, a first end suitable to house a first explosive cartridge (7) and a second end open to allow exit of a projectile shot from the explosive cartridge (7), characterized in that there is provided at least one auxiliary firing chamber (2) communicating with the internal firing chamber of the shooting barrel (1) i an intermediate area between the first and the second end of the shooting barrel (1).

2. Firearm as claimed in claim 1 , wherein the at least one auxiliary firing chamber (2) is suitable to house a respective second explosive cartridge (4, 4a).

3. Firearm as claimed in claim 2, wherein means (5a) are provided suitable to make said second cartridge (4, 4a) explode through the action of expansion of the gases produced by a shot of the first cartridge (7).

4. Firearm as claimed in claim 3, wherein said means suitable to make the second cartridge (4, 4a) explode include means suitable to make the second cartridge (4, 4a) translate to move against a firing pin (5a) integral with said at least one auxiliary firing chamber (2).

5. Firearm as claimed in claim 4, wherein the shooting barrel (1) and the at least one auxiliary firing chamber (2) communicate through one or more holes (3) provided on the barrel (1).

6. Firearm as claimed in claim 5, wherein said one or more holes (3) are placed at a distance from the first end of the shooting barrel (1) greater than the length of the first cartridge (7).

7. Firearm as claimed in claim 6, wherein the at least one auxiliary firing chamber (2), is paced with its axis essentially parallel to the longitudinal axis of the barrel (1) and the one or more holes (3) are at an end of it distal from the second explosive cartridge (4, 4a).

8. Firearm as claimed in one of the previous claims, wherein a second auxiliary firing chamber (2a) is provided communicating with the shooting barrel (1) and suitable to contain a respective second cartridge (4, 4a).

9. Firearm as claimed in claim 8, wherein said first and second auxiliary firing chambers (2, 2a) communicate with the shooting barrel (1) at the same distance from one end of the shooting barrel (1).

10: Firearm as claimed in claim 8, wherein said first and second auxiliary firing chambers (2, 2a) communicate with the shooting barrel (1) at different distances from one end of the shooting barrel (1).

11. Firearm as claimed in claim 4, wherein the firing pin (5a) is positioned in a distal area of the auxiliary firing chamber (2) with respect to the shooting barrel (1).

12. Process to shoot a projectile implemented by means of a firearm as claimed in claim 1 , comprising the following stages: a) explosion of the first cartridge (7) provided with projectile in the shooting barrel, so as to produce first pressurized explosion gases suitable to impart a first acceleration on the projectile, b) input of at least part of the first explosion gases into the auxiliary firing chamber (2) through communication holes (3) between the barrel (1) and the auxiliary firing chamber (2), c) ignition of an explosive charge of the second blank cartridge (4, 4a) disposed in the auxiliary firing chamber (2), by means of ignition activated through the action of said at least part of the first explosion gases, so as to produce second pressurized explosion gases, suitable to impart a second acceleration on the projectile, by expanding in the shooting barrel.

13. Shooting process as claimed in the previous claim, wherein ignition of the secondary cartridge takes place simultaneously at two of its ends.

14. Shooting cartridge suitable to be utilized with a firearm as claimed in claim 1 , comprising a cylindrical body closed at a first end, a priming capsule (14) disposed at the first end, a capsule (9) that closes a second end opposite the first, characterized in that it comprises inside the cylindrical body a raised annular edge (4c) forming a stop for the capsule (9) and priming explosive means disposed between said capsule (9) and said annular edge (4c) and in that the capsule is suitable to slide for a limited amplitude through the action to expand explosive gases so as to press said priming explosive means (11) against said annular edge (4c).

15. Shooting cartridge as claimed in the previous claim wherein said priming explosive means form a ring.

16. Shooting cartridge as claimed in the previous claim wherein the capsule (9) has a closure (9a), the plane of which is star shaped with stress raisers.