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Danko Priimak
United States Patent Application

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Patent Application of Danko Priimak for

Title: Reverse Ignition Cartridge


     Not applicable.


Field of the invention
     The present invention relates to fire ammunition, more particularly to the design of cartridges for fire-arms weapon. It might be used for increasing range and accuracy of aimed fire and destructive power of existing and newly developed small arms as well.

Description of Prior Art
     Conventional cartridges for small arms, used everywhere, contain powder charge, confined in case volume, bearing an igniter primer on one side and a bullet on the other side. Such cartridges produce random spread of results in aimed fire shooting, despite the stable composition, powder uniformity, accuracy and consistency of powder weight in powder loads, identity of case volumes, reproducibility of bullet’s mass and shape.

     In such cartridges as described in U.S. Patents 5,151,555 to Vastvog (1992) and 5,708,231 to Koon (1998), powder is ignited from the primer side, developing pressure of powder gases in the cartridge. Portion of powder, which is in close proximity to the bullet, is carried away under the pressure of powder gases, following the bullet, which cause incomplete combustion of powder charge and clogging of the barrel bore.

     The above mentioned shortcoming is partially overcome in the cartridge disclosed in U.S. Patent 4,149,465 to Verkozen (1979), where a primer ignites a combustible or an explosive hollow tubular element, extending axially of the cartridge from the primer through the powder charge in the cartridge to the other side of the cartridge. But the analysis of the process of igniting powder charge in time shows that powder combustion is developing in asymmetric random way, starting predominantly in the places of bursts or burn-through spots, which excludes consistency of dynamics of development of powder gas pressure from shot to shot. The portions of the main powder charge, being ignited along the longitudinal axis of cartridge, get pressed to the cartridge case walls. But combustion of the main powder starts predominantly from the primer side, therefore 
portion of the powder charge, located between combustion zone and bullet, is being swept away towards the bullet by the pressure of powder gases and follows the bullet on firing to the barrel bore. Thus, the extent of powder combustion is still not high enough. The next shortcoming of this type of cartridge: powder, filling in the cartridge case, being loose, is freely migrating inside the cartridge under gravitation forces, when changing the space orientation of cartridge. Therefore, powder charge at the firing moment has undefined space configuration, which enhances combustion asymmetry. From above mentioned follows, that dynamics of pressure development in the cartridge is unique for every shot, which turns out to be one of the main reasons for spread of the results in a particular series of shots.

     U.S. Patent 2,759,419 to Hitchens (1956) discloses an igniter cartridge, designed to ignite a fuel-air mixture in the combustion chamber of a jet engine. This cartridge comprises a hollow flash tube, passing through the cartridge coaxially to the longitudinal axis of the cartridge and extending from the primer to the opposite end of 
the cartridge. It is made of combustible metal and closed at the end, nearest to the ignition charge by crimping and sealing the end. This flash tube facilitates ignition by directing the flash from the primer to a readily ignitable charge in the front end of the cartridge. In firing this cartridge, the flash from the primer passes through the 
hollow flash tube and burst open the closed end to set off the surrounding ignition charge which in its turn ignites the main charge inside the cartridge. The dynamics in development of powder gas pressure directly 
depend on the shape and location of the initial combustion front of the burning powder charge. But the shape and direction of the breakage of the closure in flash tube are unpredictable and random. Therefore, the parameters of the initial combustion front and dynamics in pressure development produced by powder gases are not reproducible from shot to shot. This shortcoming is not taken into consideration in the described U.S. 
Patent 2,759,419, because the authors of this invention use powder charge not for powder development of powder gas pressure, which is necessary for propelling the bullet, but for igniting the main, slowly burning, metal-containing charge, which, in its turn, ignites fuel-air mixture in jet engines.


     In accordance with this invention a reverse ignition cartridge comprises a primer, a cartridge case, a flash tube, extending from the primer through a powder charge and made of non-ignitable by primer material, a fast burning diaphragm, securing a shape of a powder charge and reverse igniting on firing the charge from the second end of the flash tube, facing a bullet.

Objects and advantages
     Accordingly, several objects and advantages of the present invention are:
- to provide a complete combustion of a powder charge, which is achieved by ignition of the end surface of the powder charge, facing the bullet.
- to exclude clogging of the barrel bore by powder particles due to complete burning of powder charge. - to reduce a spread of shooting results owing to uniform and complete burning of powder charge in a series of shots.
- to enhance accuracy of shooting due to similar development of powder combustion processes, defined by alike powder shape and uniform initial combustion front, which is achieved by igniting a diaphragm.
- to increase range of fire by directing o a jet of gases developed in the powder burning process, by choosing a proper shape of ignition diaphragm.
- to provide reproducible initial speed of the bullet, not depending on space orientation of a cartridge in gravitation field of the Earth at the firing moment.
- to enable a more accurate prediction of a speed of powder combustion, and as a result, of shooting characteristics either, by choosing a proper powder type with demanded combustion speed.

     Still further objects and advantages will become apparent from a consideration of the ensuing description, 
taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts 


     FIG.1 is a side elevation partly in section showing a completed cartridge embodying this invention (the first embodiment). 
     FIG.2 is a fragmentary sectional view of the upper portion of a cartridge, showing the relation between a flash tube and a funnel-shaped ignition diaphragm (the second embodiment).
     FIG.3 is a fragmentary sectional view of the upper portion of a cartridge, comprising in addition to the one, shown in FIG.1, a combustible porous element (the third embodiment).
     FIG.4 is a fragmentary sectional view of the upper portion of a cartridge, having a funnel-shaped diaphragm and a combustible porous element (the fourth embodiment).

Reference Numerals in Drawings
     1 cartridge case
     2 primer
     3 powder charge
     4 flash tube
     5 bullet
     6 igniting diaphragm
     7 glue
     8 combustible element


     The first embodiment of the present invention is illustrated in FIG.1. The reverse ignition cartridge comprises a cartridge case 1 carrying a primer 2 and a powder charge 3. The cartridge further comprises a flash tube 4, which is press-fitted or otherwise secured from the first open end in the usual primer cavity of the cartridge case 1. The flash tube 4 extends from contact with primer 2, coaxially with the cartridge case 1, so that the second end of the cartridge is facing a bullet 5. The flash tube 4, open at the second, upper end, is passing through the powder charge 3, protruding beyond the powder charge 3. The flash tube 4 is made of plastic, paper or other material, which is either incombustible or combustible in the burning powder charge 3, which surrounds the flash tube 4. According to the present invention, the material of the flash tube 4 and its thickness should prevent the fragmentation of the flash tube 4 under the pressure of powder gases. Powder charge 3 is filling in the cartridge case 1 up to the level, defined by the length of the flash tube 4. The shape of a surface of the powder charge 3 is secured by an ignition diaphragm 6, which represents a round washer, made from fast-burning material, for instance, pressed out from plasticized trinitrate cellulose. The ignition diaphragm 6 after filling the cartridge case 1 by powder charge 3, get pressed to the latter and sealed along the perimeter to the cartridge case 1 by a liquid glue 7, for instance, a solution of trinitrate cellulose in organic solvents. The external diameter of the ignition diaphragm is equal to the internal diameter of the cartridge case 1, and the diameter of an aperture in the center of the ignition diaphragm 6 corresponds to the external diameter of the flash tube 4, so as to enable the flash tube 4 to pass through and be disposed in this aperture. The ignition diaphragm 6, thus, before shooting performs a function of a wad and secures the shape of the powder charge 3 unchanged, isolating thereby the powder charge 3 from direct reach by primer flash, outcoming from the second open end of the flash tube 4.

     On firing, a flame of very hot gases is directed from primer 2 through the flash tube 4 into the cavity between the bullet 5 and the ignition diaphragm 6 and sets the latter off. Fast burning ignition diaphragm 6 in its turn ignites the end surface of the powder charge 3, facing the bullet 5. The high burning speed of ignition diaphragm 6, being higher than the speed of powder combustion, assures a reliable, symmetrical ignition of the end of the powder charge 3. The nascent smooth combustion front is moving towards the cartridge base 2, while the powder charge 3 is burning, the combustion front retaining throughout the burning cycle the initial shape, defined by the shape of ignition diaphragm 6. Because the powder charge 3 throughout the burning process is retained pressed down towards the primer 2 by the pressure of powder gases, it burns completely, with no residue left and no clogging of the barrel. Such uniformity of the shape of the powder charges in different cartridges and similarity of ignition process of the powder charges define the identity of the burning processes in time and throughout the powder charge 3 inside the cartridge case 1 in repeated shots. Therefore, dynamics of gas pressure development in time is reproducible from shot to shot, resulting in the same bullet speed at the outcome from the barrel. This provides gain in accuracy of fire-arms.

     Because combustion dynamics of powder charge is to the significant extent determined by the location and the shape of the initial combustion zone, varying the shape of the ignition diaphragm 6 allows to control the combustion dynamics of the powder charge 3. FIG.2 shows a fragment of the cartridge, where the powder charge 3 is forming a cone-shaped recess by using ignition diaphragm 6, made in the form of a tapered funnel. The nascent combustion zone of the powder charge 3, moving towards the bottom of the cartridge case 1 as powder charge 3 is burning, retains its tapered form up to completion of charge burning. The gases evolving on powder charge burning are directed so that their displacement vector, outgoing from the combustion surface is perpendicular to this surface. Therefore, the gases when meet on the axis of the cone, create thin dense ‘cord’, in which practically all the kinetic energy of the combustion products is concentrated. Jet of powder gases in such ‘cord’ and their pressure are directed along the longitudinal axis of the cartridge 1, predominantly towards the bullet 5. Thus, on firing using the cartridge according to the present invention in comparison with the known cartridges, provided the charge mass is the same, bullet 5 receives considerably higher power impulse and has higher speed at the moment of escape out of the barrel. Further advantages of this cartridge are: lesser gas pressure onto the shell walls, which allows to make cartridge case 1 with thinner walls and lesser energy of exhaust gases from the barrel after escape of the bullet 5. It is explained by anisotropy of gas pressure, the latter being much higher in direction towards the bullet 5, and also, by small residual energy of exhaust gases, since the larger portion of gas energy is transformed into kinetic energy of the bullet 5, rising the bullet speed.

     FIG.3 and FIG.4 represent the other embodiments of the present invention, where the cartridge 1 comprises in addition a combustible element 8, which increases the reliability of ignition of diaphragm 6. Combustible element 8 represents a porous wad of fibres, made of easy ignitable and fast burning material, for instance, trinitrate cellulose. After installation of the ignition diaphragm 6, combustible element 8 is placed in the center of the ignition diaphragm 6 and pressed down to the powder charge 3 and is sealed to external surface of the protruding end of the flash tube 4, closing thereby the outlet aperture of the latter. The external surface of the second end of the flash tube 4 is covered by the liquid glue 7.

     On firing, primer flash is passing through the porous texture of the combustible element 8, igniting the latter. The combustible element 8 in its turn ignites the diaphragm 6, facilitating and assuring a reliable flash transfer from primer 2 to the ignition diaphragm 6. Thereafter the combustion process will proceed the same way as it is described above.


     1. In a reverse ignition cartridge having a base at one end with a central aperture therethrough, a primer disposed in said aperture, a propellant powder charge disposed in said cartridge and a flash tube having the first end open and extending from said primer through said powder charge coaxially in said cartridge, the improvement comprising an ignition diaphragm with a central aperture, said ignition diaphragm being pressed down onto said powder charge so as to secure a shape of said powder charge, the second end of said flash tube being disposed in the said aperture of said ignition diaphragm.
     2. The reverse ignition cartridge of claim 1, wherein said ignition diaphragm has a tapered funnel form so as to provide a directed jet of powder gases predominantly in a direction of longitudinal axis of said cartridge whereby a range of fire is increased. 
     3. The reverse ignition cartridge of claims 1 or 2, wherein the second end of said flash tube is supplied by a combustible element, so as to assure a reliable flash transfer from said primer to said ignition diaphragm.


     Abstract: A reverse ignition cartridge for firearms is provided, in which the shape of a powder charge is secured by a diaphragm, made of fast burning material. Shot initiation is produced by igniting the diaphragm by a primer flash through a flash tube disposed in an aperture of said diaphragm. The flash tube extends coaxially through the powder charge from primer to the diaphragm.

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