Jacketed projectile having a variable density core

Abstract

A jacketed powder core projectile has a variable density core, which includes a high density zone, a mixed density zone, and a low density zone. The low density zone is formed forward of the distal end of the jacket to define a hollow point nose of the projectile. The high density zone is formed about the inner surface of the jacket and extends radially inward to the mixed density zone, which is formed concentrically about the longitudinal axis of the projectile. The high density zone may taper from an internal base of the jacket to the distal end thereof.

Description

BACKGROUND OF THE INVENTIONField of the Invention

[0001] The present invention relates generally to ammunition projectiles, and more particularly to jacketed projectiles having a variable density powdered core and methods for making the same.Description of Related Art

[0002] Ammunition cartridges of the type commonly used in modern firearms are generally well known in the art. These cartridges include a cylindrical case that carries an internal payload, e.g., propellant powder, and has an open forward end for removably engaging a projectile. The specific size and shape of the cartridge and projectile is dependent on the firearm used. The rearward end is typically closed around a means for igniting the internal payload, typically in the form of a primer that is disposed in the center of the base of the cartridge. The projectile is discharged from the cartridge by igniting the internal payload. When chambered in a firearm, a firing pin or other type of firing mechanism strikes the primer producing a flash that ignites the propellant powder within the cartridge causing the projectile to be propelled forward out of the firearm.

[0003] Conventional firearm projectiles or bullets have been made from malleable metallic materials such as lead and various lead alloys. The lead bullets may be enclosed in a jacket made of separate metallic material that is harder than lead, typically copper but other metals may also be used. These are known as jacketed bullets and can be fully jacketed, e.g., the jacket entirely covers the lead core, or partially jacketed, e.g., the base or nose may be partially exposed. In some types of bullets, the nose end may be formed as a hollow point, which is a known bullet design having a small indentation or cavity formed in the distal end of the bullet. Hollow point bullets are known to mushroom or deform upon impact with a soft target, such as organic tissue. The deformation of the hollow point bullet in the target, however, limits its penetration through the target. While the mushroom effect of the hollow point increases the diameter of the internal wound cavity beyond the initial diameter of the bullet, it might not be sufficient to incapacitate the target, especially when the bullet hits nonvital regions of the target.

[0004] Other types of known projectiles include disintegrating bullets, which typically include a jacket enclosing a frangible core made of low density materials, e.g., lower density than lead. These bullets can be formed with a hollow point, rounded or pointed tip nose, as is known in the art. Disintegrating bullets deform or fracture into small pieces upon hitting a target. A drawback for this type of bullet is that the use of low density materials for the core causes a decrease in sectional density which decreases the ballistic coefficient, ultimately causing degradation in terminal ballistics performance.

[0005] Thus, what is needed are bullets that maintain the advantages of a high sectional density and are capable of disintegrating in a target to increase damage caused by the bullet.SUMMARY OF THE INVENTION

[0006] The above problems are overcome by the variable density core projectiles according to the present invention. The inventive projectile and methods for manufacturing the same improve the terminal ballistic performance of the projectile in an organic target, such as large game animals. The projectiles according to the present invention have a variable density core that increases stability during flight and can therefore increase accuracy of the projectile and precision among a group of similarly fired projectiles.

[0007] In one embodiment, the invention relates to a projectile having a variable density core. The variable density core has a high density zone, a mixed density zone, and a low density zone. A jacket at least partially encloses the core. The low density zone may form a nose of the projectile, which may, optionally, include a hollow cavity defined therein to form a hollow point nose. Preferably, the low density zone extends beyond the distal end of the jacket to form the projectile nose.

[0008] In preferred embodiments, the high density zone extends from an inner surface of the jacket to the mixed density zone. The mixed density zone is preferably concentrically aligned with a longitudinal axis of the projectile. The high density zone may have a radially symmetrical thickness. Similarly, the mixed density zone is preferably radially symmetrical about the longitudinal axis. In some alternative embodiments, the high density zone tapers from a base end toward the forward end of the jacket.

[0009] Preferably, the mixed density zone comprises a homogeneous mixture of a high density material and a low density material. In some embodiments, the high density material is a tungsten powder and the low density material is a tin powder. The high density zone is primarily composed of the high density material and the low density zone is primarily composed of the low density material.

[0010] In further embodiments, the invention relates to a method for manufacturing the projectile. Preferably, the inventive method involves compressing two or more metal powders within a jacket to form a jacketed powder core that has a hollow point nose. The two or more metal powders include a high density material and a low density material. The jacketed powder core is thereafter heated to the melting point of the low density material. The heated jacketed powder core is spun about its longitudinal axis, which causes extrusion of the low density material through the hollow point nose. The jacketed powder core is tipped to reform the hollow point nose in the extruded low density material. The spinning step causes a redistribution of the powder materials within the jacket. Preferably, the high density material forms a uniform high density zone on the inner surface of the jacket. In some more elaborate embodiments, the spinning step forms a longitudinal cavity within the projectile.

[0011] In preferred embodiments, the high density material is a tungsten metal powder and the low density material is a tin metal powder. Preferably, the low density material has a melting point that is lower than the melting point of the jacket.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the invention. Dimensions shown are exemplary only. In the drawings, like reference numerals may designate like parts throughout the different views, wherein:

[0013] FIG. 1 is a side view of a first embodiment of a projectile according to the present invention.

[0014] FIG. 2 is a cross-sectional side view, taken along lines A-A in FIG. 1, of an embodiment of a projectile according to the present invention.

[0015] FIG. 3 is a cross-sectional side view, similarly taken along line A-A in FIG. 1, of a second embodiment of a projectile according to the present invention.

[0016] FIG. 4 is a cross-sectional side view, similarly taken along line A-A in FIG. 1, of a third alternative embodiment of a projectile according to the present invention.

[0017] FIG. 5 is a flow chart diagramming the salient steps for a method for manufacturing projectiles according to the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0018] The following disclosure presents exemplary embodiments of an improved jacketed projectile having a variable density core. The variable density core according to the present invention improves flight stability of the projectile upon being discharged from a firearm. The variable density core also significantly increases the terminal ballistics of the jacketed projectile, providing devastating damage in organic tissue and other soft target material. Terminal ballistics as used herein is understood to mean the effects and behavior of the projectile upon hitting and entering target media.

[0019] Projectiles according to the present invention can be manufactured to conform to any conventional or unconventional caliber size for ammunition projectiles, including calibers for pistol, rifle, and shotgun ammunition of civilian or military grade. Further, certain types of artillery projectiles may be manufactured in accordance with the present invention. Thus, the present inventive projectiles are designed to engage a conventional ammunition cartridge of any desired caliber and be discharged from any conventional firearm of the same caliber.

[0020] FIG. 1 is a side view of a first embodiment of a jacketed projectile according to the present invention. The projectile 10 includes a jacket 12 enclosing a variable density core 14. The projectile 10 has a hollow point 16 formed at a forward end 18. In preferred embodiments, the forward end 18 has an ogive tapering into the hollow point 16, as is known in the art. As will be detailed further below, the variable density core 14 includes a high density zone 20, a mixed density zone 22, and a low density zone 24. The low density zone 24 extends beyond the distal end 26 of the jacket 12 to form the nose 28. The hollow point 16 is defined in the nose 28 formed by the low density zone 24. In preferred embodiments, the nose 28 is formed with an ogive taper from the distal end 26 of the jacket 12 into the hollow point 16.

[0021] FIG. 1 shows section lines A-A which mark a common cross-sectional line utilized for FIGS. 2 through 4. FIG. 2 is a cross-sectional view of a first embodiment of a jacketed projectile according to the present invention. As stated above, the variable density core 14 includes a high density zone 20, a mixed density zone 22 and a low density zone 24.

[0022] As used herein, high density should be understood to mean having a density greater than lead and low density is understood to mean having a density less than lead. Lead has a known density substantially equal to 11.34 grams per cubic centimeter. In a preferred embodiment, the high density zone 20 is made primarily of tungsten, which has a density of 19.3 g / cm3. In alternative embodiments, the high density zone 20 may comprise a substantially depleted uranium, which has a density of 19.1 g / cm3 The low density zone 24 is preferably made primarily of tin, which has a density of 7.31 g / cm3, although nickel with a density of 8.90 g / cm3 and aluminum with a density of 2.7 g / cm3 may also be used within the scope of the present invention. The mixed density zone 22 is a homogeneous mixture of the high density and low density materials selected, as will be explained further below. Other physical characteristics of the materials selected to make the projectile 10 according to the present invention will be highlighted and discussed below. In particular, the melting point for each material selected for the projectile 10 becomes an important factor to consider in accordance with the manufacturing method 100 disclosed herein.

[0023] The high density zone 20 is formed around the inner surface 13 of the jacket 12 and extends radially inward. In preferred embodiments, the high density zone 20 extends from the inner surface 13 of the jacket to the mixed density zone 22, which is concentrically formed around the longitudinal or spin axis of the projectile 10. The high density zone 20 may taper from an internal base 30 of the jacket 12 toward the distal end 26 thereof. When the high density zone 20 is formed with a taper, the mixed density zone 22 has a reverse taper from the distal end 26 of the jacket toward the internal base 30 thereof. The mixed density zone 22 fills up the remaining internal volume of the jacket 12 not occupied by the high density zone 20. The low density zone 24 is forward of the distal end 26 of the jacket 12 and forms the nose 28 of the projectile. The high density zone 20 preferably has a radially symmetric thickness regardless of whether zone 20 tapers.

[0024] FIG. 3 is a cross-sectional view of an alternative embodiment of the projectile according to the present invention. Again, the cross section is taken along lines A-A in FIG. 1. In alternative embodiments of the projectile 10 such as that illustrated by FIG. 3, the mixed density zone 22 may have a uniform thickness about the longitudinal axis. The high density zone 20 extends radially inward from the inner surface 13 of the jacket 12 to the mixed density zone 22 and has a relatively uniform thickness, i.e., it does not taper. The high density zone 20 follows the curvature of the inner surface 13 of the jacket 12, which provides a variable thickness of the high density zone 20 as shown in FIG. 3. The low density zone 24 is formed forward of the distal end 26 of the jacket 12 to form the projectile nose 28.

[0025] FIG. 4 is a cross-sectional view of another embodiment of a projectile according to the present invention. FIG. 4 is taken along the common section line A-A marked in FIG. 1. In some more elaborate embodiments, a cavity 32 may be formed in the low density zone 24 and the mixed density zone 22. Preferably, the cavity 32 is concentrically aligned with the longitudinal axis of the projectile 10. The cavity 32 may extend from a nose opening 34 to the internal base 30 of the jacket 12. The nose opening 34 is defined through a center point of the hollow point 16 of the nose 28 formed by the low density zone 24. The cavity 34 is free from all materials, i.e., there are no high nor low density materials present in the cavity. The presence of the cavity 34 may further increase the terminal ballistics of the projectile 10. The cavity 34 may be formed in embodiments having a tapered high density zone 20 (e.g., FIG. 2) and a relatively uniformly thick high density zone 20 (e.g., FIG. 3). In alternative embodiments, the cavity 32 may extend through the internal base 30 of the jacket 12 to define an open-ended channel extending fully through the length of the projectile 10.

[0026] In preferred embodiments, the variable density core 14 is a powdered core made from two or more metal powders, preferably a high density metal powder and a low density metal powder. The high density metal powder is preferably a tungsten powder and the low density metal powder is preferably a tin powder, although nickel or aluminum powders may also be used for the low density material.

[0027] FIG. 5 is a process flow chart illustrating salient steps of a method for manufacturing projectiles according to the present invention. The method 100 begins with forming 102 a jacketed powder core according to conventional bullet forming techniques known in the art for powdered core bullets. The formation step 102 thus may involve homogeneously combining two or more metal powders, e.g., a high density metal powder and a low density metal powder, and cold-compressing the powders into a self-supporting cylindrical shape. The specific concentration of each respective metal powder may be varied depending on the requirements of the projectile and desired terminal ballistics. In preferred embodiments, there is about 90% by weight of high density metal powder (e.g., a tungsten powder) and about 10% by weight of low density metal powder (e.g., a tin powder). In other embodiments, the concentration of metal powders may be 70% high density metal powder and 30% low density metal powder. Further alternative concentrations of the high density material and the low density material may be used in accordance with the disclosed invention, although it is preferred that the concentration of the high density material be at least equal to about 50% by weight. The specific concentrations of powdered metal materials used for a given core informs the amount of pressure required to cold-compress the powders into the self-supporting shape. High concentrations of the high density material require higher compression pressures to form the self-supporting cylindrical shape.

[0028] The powdered core is seated in a jacket, which at this point in method 100 is an elongated cup having an open forward end. In preferred embodiments, the jacket is a conventional copper jacket, although brass and other metal jackets may also be used. In all embodiments, the material selected for the jacket must have a melting point that is higher than at least the low density material of the core. Thus, in some embodiments, a polytetrafluoroethylene, commonly known as Teflon, jacket may be used when the low density material is tin, i.e., melting point of Teflon is 6200 Fahrenheit while the melting point of tin is 449.50 Fahrenheit. When a boattail is required, the powdered core and jacket combination is die pressed in a boattail forming die according to conventional bullet forming techniques. Once the base end has been formed, either with or without a boattail, the powdered core and jacket combination is die pressed in an ogive forming die. The jacketed powder core is formed with a hollow point nose at the forward end and is balanced about its longitudinal or spin axis, e.g., axis of rotation during normal flight.

[0029] The next several steps may be accomplished using a rotary motor and a collar heater. The rotary motor defines an axis of rotation that is normal to the longitudinal axis of the projectile to impart a centrifugal force on the projectile. It is preferred to orient the rotary motor so that the projectile is concentrically aligned at the center of the rotational axis, with the forward end 18 pointing upwards. The vertical orientation of the projectile on the motor allows the method 100 to utilize gravitational forces to aid the redistribution of the core materials, as discussed below. Depending on the type of rotary motor used, a collet may be necessary to hold the projectile in the proper position and orientation. The collar heater is preferably a programmable doughnut shaped heater that can be concentrically arranged around the projectile positioned on the rotary motor. The heater is programmed to a temperature equal to the melting point of the low density material. Thus, various types of known equipment can be utilized to accomplish the following steps.

[0030] After the jacketed powder core is formed in step 102, the projectile is heated at step 104, using the collar heater described above, to the melting point of the low density material. In the preferred embodiments described herein, the low density material is tin and the projectile is heated to the melting point of tin, which is known to be about 449.50 Fahrenheit. Upon reaching the melting point of the low density material, the projectile is spun at step 106, using the rotary motor described above while the collar heater continues to heat the projectile. Alternatively, the heating 104 and spinning 106 steps may be accomplished simultaneously, e.g., the projectile is spun while being heated to the melting point of the low density material. In such embodiments, the heating step 104 continues throughout the duration of the spinning step 106.

[0031] The heating 104 and spinning 106 steps cause a redistribution of the powder materials within the jacket to form the high density zone 20, the mixed density zone 22 and the low density zone 24. The projectile is preferably spun at a rate of about 8,000 rotations per minute (“RPM”). As the projectile is spun during step 106, the pressure within the jacket is increased, which, in combination with the centrifugal forces generated by spinning 106, causes molten low density material to extrude through the hollow point nose of the projectile. The extruded low density material is concentrated forward of the distal end 26 of the jacket 12. The molten low density material immediately quenches upon being exposed to the ambient atmosphere after extrusion through the hollow point. The low density zone 24 is formed by the extruded low density material, as will be detailed further below. Excess low density material may be wiped away or otherwise removed prior to reshaping the low density zone into the nose, as detailed further below. Simultaneously with the extrusion of low density material, the high density material, still in a solid state, is redistributed within the jacket. The high density material is forced through the molten low density material to the inner surface of the jacket forming the high density zone 20. Normal gravitational forces acting on the material may give the high density zone 20 the tapered configuration, such as that shown among the embodiment illustrated by FIG. 2, as gravity forces more high density material to settle around the internal base 30 of the jacket 12. The mixed density zone 22 results as a byproduct of the redistribution of the powders during the heating 104 and spinning 106 steps.

[0032] The projectile is typically spun at step 106 for about one minute after reaching the melting point of the low density material in step 104. The time of the spinning step 106 can be used to control the redistribution of the powdered metals forming the core and thus control the size of each respective zone formed thereby. Spinning for less than one minute can result in smaller high density zone 20 being formed around the inner surface 13 of the jacket 12. Spinning the projectile beyond one minute can increase the high density zone 20 and eventually causes the formation of the cavity 32 in the core 14. Further, the rotational speed utilized during the spinning step 106 may also be a means to control the redistribution of the powdered metals within the jacket. Spinning the projectile at higher RPMs will cause more of the high density powder materials to redistribute toward the inner surface of the jacket.

[0033] After the heating 104 and spinning 106 steps are complete, the projectile is tipped 108 to form the nose 28 in the low density zone 24 with a hollow point 16. Tipping 108 can be accomplished according to conventional tipping methods, e.g., by mechanically pressing the projectile upwards into a tipping die having the desired nose profile. The extruded low density material is formed into the nose 28, which is now primarily made up of the low density materials.

[0034] The projectiles 10 manufactured according to the present inventive method 100 exhibit increased flight stability. The concentration of high density materials in the high density zone 20 around the inner surface 13 of the jacket 12 produces a stabilizing effect during flight, reducing the occurrence of yaw or the rotation of the forward end of the bullet off the flight axis.

[0035] Further, the terminal ballistics for projectiles 10 manufactured according to the present inventive method 100 are significantly increased. The lower density metal forming the low density zone 24 in the projectile nose 28 readily deforms upon impact with an organic target while the copper jacket 12 enclosing the high density materials continues to penetrate. The momentum behind the projectile 10 causes the projectile to penetrate the target after the initial contact and deformation of the nose. As the projectile penetrates, the organic fluid, e.g., blood, bodily fluids, and other soft tissue, fills vacated areas within the core causing the projectile to disintegrate radially outwards in the organic target. This causes a devastating wound in the target. The individual particles of the high density material and low density material are dispersed radially outwards in the target, each serving as a micro-fragment imparting damage to the surrounding tissue. The tissue damage caused by these micro-fragments spreads well beyond the diameter of the projectile, causing an almost immediately incapacitating wound in the target.

[0036] The vacated areas within the core 14 are created by the redistribution of the core materials during steps 104 and 106 of the method 100. Due to the upward extrusion of the low density material to form the low density zone 24 at the nose 28, cavities are formed in the mixed density zone 22 and the high density zone 20 where the low density material has been extruded, e.g., microscopic cavities are formed in place of each individual low density powder particle that is melted and extruded forward. Upon impacting an organic target, these microscopic cavities are filled with the organic matter as the projectile continues through the target, eventually causing the projectile to disintegrate radially outward in the target.

[0037] Exemplary embodiments of the invention have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.

Examples

Embodiment Construction

[0018]The following disclosure presents exemplary embodiments of an improved jacketed projectile having a variable density core. The variable density core according to the present invention improves flight stability of the projectile upon being discharged from a firearm. The variable density core also significantly increases the terminal ballistics of the jacketed projectile, providing devastating damage in organic tissue and other soft target material. Terminal ballistics as used herein is understood to mean the effects and behavior of the projectile upon hitting and entering target media.

[0019]Projectiles according to the present invention can be manufactured to conform to any conventional or unconventional caliber size for ammunition projectiles, including calibers for pistol, rifle, and shotgun ammunition of civilian or military grade. Further, certain types of artillery projectiles may be manufactured in accordance with the present invention. Thus, the present inventive project...

BACKGROUND OF THE INVENTIONField of the Invention

[0001] The present invention relates generally to ammunition projectiles, and more particularly to jacketed projectiles having a variable density powdered core and methods for making the same.Description of Related Art

[0002] Ammunition cartridges of the type commonly used in modern firearms are generally well known in the art. These cartridges include a cylindrical case that carries an internal payload, e.g., propellant powder, and has an open forward end for removably engaging a projectile. The specific size and shape of the cartridge and projectile is dependent on the firearm used. The rearward end is typically closed around a means for igniting the internal payload, typically in the form of a primer that is disposed in the center of the base of the cartridge. The projectile is discharged from the cartridge by igniting the internal payload. When chambered in a firearm, a firing pin or other type of firing mechanism strikes the primer producing a flash that ignites the propellant powder within the cartridge causing the projectile to be propelled forward out of the firearm.

[0003] Conventional firearm projectiles or bullets have been made from malleable metallic materials such as lead and various lead alloys. The lead bullets may be enclosed in a jacket made of separate metallic material that is harder than lead, typically copper but other metals may also be used. These are known as jacketed bullets and can be fully jacketed, e.g., the jacket entirely covers the lead core, or partially jacketed, e.g., the base or nose may be partially exposed. In some types of bullets, the nose end may be formed as a hollow point, which is a known bullet design having a small indentation or cavity formed in the distal end of the bullet. Hollow point bullets are known to mushroom or deform upon impact with a soft target, such as organic tissue. The deformation of the hollow point bullet in the target, however, limits its penetration through the target. While the mushroom effect of the hollow point increases the diameter of the internal wound cavity beyond the initial diameter of the bullet, it might not be sufficient to incapacitate the target, especially when the bullet hits nonvital regions of the target.

[0004] Other types of known projectiles include disintegrating bullets, which typically include a jacket enclosing a frangible core made of low density materials, e.g., lower density than lead. These bullets can be formed with a hollow point, rounded or pointed tip nose, as is known in the art. Disintegrating bullets deform or fracture into small pieces upon hitting a target. A drawback for this type of bullet is that the use of low density materials for the core causes a decrease in sectional density which decreases the ballistic coefficient, ultimately causing degradation in terminal ballistics performance.

[0005] Thus, what is needed are bullets that maintain the advantages of a high sectional density and are capable of disintegrating in a target to increase damage caused by the bullet.SUMMARY OF THE INVENTION

[0006] The above problems are overcome by the variable density core projectiles according to the present invention. The inventive projectile and methods for manufacturing the same improve the terminal ballistic performance of the projectile in an organic target, such as large game animals. The projectiles according to the present invention have a variable density core that increases stability during flight and can therefore increase accuracy of the projectile and precision among a group of similarly fired projectiles.

[0007] In one embodiment, the invention relates to a projectile having a variable density core. The variable density core has a high density zone, a mixed density zone, and a low density zone. A jacket at least partially encloses the core. The low density zone may form a nose of the projectile, which may, optionally, include a hollow cavity defined therein to form a hollow point nose. Preferably, the low density zone extends beyond the distal end of the jacket to form the projectile nose.

[0008] In preferred embodiments, the high density zone extends from an inner surface of the jacket to the mixed density zone. The mixed density zone is preferably concentrically aligned with a longitudinal axis of the projectile. The high density zone may have a radially symmetrical thickness. Similarly, the mixed density zone is preferably radially symmetrical about the longitudinal axis. In some alternative embodiments, the high density zone tapers from a base end toward the forward end of the jacket.

[0009] Preferably, the mixed density zone comprises a homogeneous mixture of a high density material and a low density material. In some embodiments, the high density material is a tungsten powder and the low density material is a tin powder. The high density zone is primarily composed of the high density material and the low density zone is primarily composed of the low density material.

[0010] In further embodiments, the invention relates to a method for manufacturing the projectile. Preferably, the inventive method involves compressing two or more metal powders within a jacket to form a jacketed powder core that has a hollow point nose. The two or more metal powders include a high density material and a low density material. The jacketed powder core is thereafter heated to the melting point of the low density material. The heated jacketed powder core is spun about its longitudinal axis, which causes extrusion of the low density material through the hollow point nose. The jacketed powder core is tipped to reform the hollow point nose in the extruded low density material. The spinning step causes a redistribution of the powder materials within the jacket. Preferably, the high density material forms a uniform high density zone on the inner surface of the jacket. In some more elaborate embodiments, the spinning step forms a longitudinal cavity within the projectile.

[0011] In preferred embodiments, the high density material is a tungsten metal powder and the low density material is a tin metal powder. Preferably, the low density material has a melting point that is lower than the melting point of the jacket.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the invention. Dimensions shown are exemplary only. In the drawings, like reference numerals may designate like parts throughout the different views, wherein:

[0013] FIG. 1 is a side view of a first embodiment of a projectile according to the present invention.

[0014] FIG. 2 is a cross-sectional side view, taken along lines A-A in FIG. 1, of an embodiment of a projectile according to the present invention.

[0015] FIG. 3 is a cross-sectional side view, similarly taken along line A-A in FIG. 1, of a second embodiment of a projectile according to the present invention.

[0016] FIG. 4 is a cross-sectional side view, similarly taken along line A-A in FIG. 1, of a third alternative embodiment of a projectile according to the present invention.

[0017] FIG. 5 is a flow chart diagramming the salient steps for a method for manufacturing projectiles according to the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0018] The following disclosure presents exemplary embodiments of an improved jacketed projectile having a variable density core. The variable density core according to the present invention improves flight stability of the projectile upon being discharged from a firearm. The variable density core also significantly increases the terminal ballistics of the jacketed projectile, providing devastating damage in organic tissue and other soft target material. Terminal ballistics as used herein is understood to mean the effects and behavior of the projectile upon hitting and entering target media.

[0019] Projectiles according to the present invention can be manufactured to conform to any conventional or unconventional caliber size for ammunition projectiles, including calibers for pistol, rifle, and shotgun ammunition of civilian or military grade. Further, certain types of artillery projectiles may be manufactured in accordance with the present invention. Thus, the present inventive projectiles are designed to engage a conventional ammunition cartridge of any desired caliber and be discharged from any conventional firearm of the same caliber.

[0020] FIG. 1 is a side view of a first embodiment of a jacketed projectile according to the present invention. The projectile 10 includes a jacket 12 enclosing a variable density core 14. The projectile 10 has a hollow point 16 formed at a forward end 18. In preferred embodiments, the forward end 18 has an ogive tapering into the hollow point 16, as is known in the art. As will be detailed further below, the variable density core 14 includes a high density zone 20, a mixed density zone 22, and a low density zone 24. The low density zone 24 extends beyond the distal end 26 of the jacket 12 to form the nose 28. The hollow point 16 is defined in the nose 28 formed by the low density zone 24. In preferred embodiments, the nose 28 is formed with an ogive taper from the distal end 26 of the jacket 12 into the hollow point 16.

[0021] FIG. 1 shows section lines A-A which mark a common cross-sectional line utilized for FIGS. 2 through 4. FIG. 2 is a cross-sectional view of a first embodiment of a jacketed projectile according to the present invention. As stated above, the variable density core 14 includes a high density zone 20, a mixed density zone 22 and a low density zone 24.

[0022] As used herein, high density should be understood to mean having a density greater than lead and low density is understood to mean having a density less than lead. Lead has a known density substantially equal to 11.34 grams per cubic centimeter. In a preferred embodiment, the high density zone 20 is made primarily of tungsten, which has a density of 19.3 g / cm3. In alternative embodiments, the high density zone 20 may comprise a substantially depleted uranium, which has a density of 19.1 g / cm3 The low density zone 24 is preferably made primarily of tin, which has a density of 7.31 g / cm3, although nickel with a density of 8.90 g / cm3 and aluminum with a density of 2.7 g / cm3 may also be used within the scope of the present invention. The mixed density zone 22 is a homogeneous mixture of the high density and low density materials selected, as will be explained further below. Other physical characteristics of the materials selected to make the projectile 10 according to the present invention will be highlighted and discussed below. In particular, the melting point for each material selected for the projectile 10 becomes an important factor to consider in accordance with the manufacturing method 100 disclosed herein.

[0023] The high density zone 20 is formed around the inner surface 13 of the jacket 12 and extends radially inward. In preferred embodiments, the high density zone 20 extends from the inner surface 13 of the jacket to the mixed density zone 22, which is concentrically formed around the longitudinal or spin axis of the projectile 10. The high density zone 20 may taper from an internal base 30 of the jacket 12 toward the distal end 26 thereof. When the high density zone 20 is formed with a taper, the mixed density zone 22 has a reverse taper from the distal end 26 of the jacket toward the internal base 30 thereof. The mixed density zone 22 fills up the remaining internal volume of the jacket 12 not occupied by the high density zone 20. The low density zone 24 is forward of the distal end 26 of the jacket 12 and forms the nose 28 of the projectile. The high density zone 20 preferably has a radially symmetric thickness regardless of whether zone 20 tapers.

[0024] FIG. 3 is a cross-sectional view of an alternative embodiment of the projectile according to the present invention. Again, the cross section is taken along lines A-A in FIG. 1. In alternative embodiments of the projectile 10 such as that illustrated by FIG. 3, the mixed density zone 22 may have a uniform thickness about the longitudinal axis. The high density zone 20 extends radially inward from the inner surface 13 of the jacket 12 to the mixed density zone 22 and has a relatively uniform thickness, i.e., it does not taper. The high density zone 20 follows the curvature of the inner surface 13 of the jacket 12, which provides a variable thickness of the high density zone 20 as shown in FIG. 3. The low density zone 24 is formed forward of the distal end 26 of the jacket 12 to form the projectile nose 28.

[0025] FIG. 4 is a cross-sectional view of another embodiment of a projectile according to the present invention. FIG. 4 is taken along the common section line A-A marked in FIG. 1. In some more elaborate embodiments, a cavity 32 may be formed in the low density zone 24 and the mixed density zone 22. Preferably, the cavity 32 is concentrically aligned with the longitudinal axis of the projectile 10. The cavity 32 may extend from a nose opening 34 to the internal base 30 of the jacket 12. The nose opening 34 is defined through a center point of the hollow point 16 of the nose 28 formed by the low density zone 24. The cavity 34 is free from all materials, i.e., there are no high nor low density materials present in the cavity. The presence of the cavity 34 may further increase the terminal ballistics of the projectile 10. The cavity 34 may be formed in embodiments having a tapered high density zone 20 (e.g., FIG. 2) and a relatively uniformly thick high density zone 20 (e.g., FIG. 3). In alternative embodiments, the cavity 32 may extend through the internal base 30 of the jacket 12 to define an open-ended channel extending fully through the length of the projectile 10.

[0026] In preferred embodiments, the variable density core 14 is a powdered core made from two or more metal powders, preferably a high density metal powder and a low density metal powder. The high density metal powder is preferably a tungsten powder and the low density metal powder is preferably a tin powder, although nickel or aluminum powders may also be used for the low density material.

[0027] FIG. 5 is a process flow chart illustrating salient steps of a method for manufacturing projectiles according to the present invention. The method 100 begins with forming 102 a jacketed powder core according to conventional bullet forming techniques known in the art for powdered core bullets. The formation step 102 thus may involve homogeneously combining two or more metal powders, e.g., a high density metal powder and a low density metal powder, and cold-compressing the powders into a self-supporting cylindrical shape. The specific concentration of each respective metal powder may be varied depending on the requirements of the projectile and desired terminal ballistics. In preferred embodiments, there is about 90% by weight of high density metal powder (e.g., a tungsten powder) and about 10% by weight of low density metal powder (e.g., a tin powder). In other embodiments, the concentration of metal powders may be 70% high density metal powder and 30% low density metal powder. Further alternative concentrations of the high density material and the low density material may be used in accordance with the disclosed invention, although it is preferred that the concentration of the high density material be at least equal to about 50% by weight. The specific concentrations of powdered metal materials used for a given core informs the amount of pressure required to cold-compress the powders into the self-supporting shape. High concentrations of the high density material require higher compression pressures to form the self-supporting cylindrical shape.

[0028] The powdered core is seated in a jacket, which at this point in method 100 is an elongated cup having an open forward end. In preferred embodiments, the jacket is a conventional copper jacket, although brass and other metal jackets may also be used. In all embodiments, the material selected for the jacket must have a melting point that is higher than at least the low density material of the core. Thus, in some embodiments, a polytetrafluoroethylene, commonly known as Teflon, jacket may be used when the low density material is tin, i.e., melting point of Teflon is 6200 Fahrenheit while the melting point of tin is 449.50 Fahrenheit. When a boattail is required, the powdered core and jacket combination is die pressed in a boattail forming die according to conventional bullet forming techniques. Once the base end has been formed, either with or without a boattail, the powdered core and jacket combination is die pressed in an ogive forming die. The jacketed powder core is formed with a hollow point nose at the forward end and is balanced about its longitudinal or spin axis, e.g., axis of rotation during normal flight.

[0029] The next several steps may be accomplished using a rotary motor and a collar heater. The rotary motor defines an axis of rotation that is normal to the longitudinal axis of the projectile to impart a centrifugal force on the projectile. It is preferred to orient the rotary motor so that the projectile is concentrically aligned at the center of the rotational axis, with the forward end 18 pointing upwards. The vertical orientation of the projectile on the motor allows the method 100 to utilize gravitational forces to aid the redistribution of the core materials, as discussed below. Depending on the type of rotary motor used, a collet may be necessary to hold the projectile in the proper position and orientation. The collar heater is preferably a programmable doughnut shaped heater that can be concentrically arranged around the projectile positioned on the rotary motor. The heater is programmed to a temperature equal to the melting point of the low density material. Thus, various types of known equipment can be utilized to accomplish the following steps.

[0030] After the jacketed powder core is formed in step 102, the projectile is heated at step 104, using the collar heater described above, to the melting point of the low density material. In the preferred embodiments described herein, the low density material is tin and the projectile is heated to the melting point of tin, which is known to be about 449.50 Fahrenheit. Upon reaching the melting point of the low density material, the projectile is spun at step 106, using the rotary motor described above while the collar heater continues to heat the projectile. Alternatively, the heating 104 and spinning 106 steps may be accomplished simultaneously, e.g., the projectile is spun while being heated to the melting point of the low density material. In such embodiments, the heating step 104 continues throughout the duration of the spinning step 106.

[0031] The heating 104 and spinning 106 steps cause a redistribution of the powder materials within the jacket to form the high density zone 20, the mixed density zone 22 and the low density zone 24. The projectile is preferably spun at a rate of about 8,000 rotations per minute (“RPM”). As the projectile is spun during step 106, the pressure within the jacket is increased, which, in combination with the centrifugal forces generated by spinning 106, causes molten low density material to extrude through the hollow point nose of the projectile. The extruded low density material is concentrated forward of the distal end 26 of the jacket 12. The molten low density material immediately quenches upon being exposed to the ambient atmosphere after extrusion through the hollow point. The low density zone 24 is formed by the extruded low density material, as will be detailed further below. Excess low density material may be wiped away or otherwise removed prior to reshaping the low density zone into the nose, as detailed further below. Simultaneously with the extrusion of low density material, the high density material, still in a solid state, is redistributed within the jacket. The high density material is forced through the molten low density material to the inner surface of the jacket forming the high density zone 20. Normal gravitational forces acting on the material may give the high density zone 20 the tapered configuration, such as that shown among the embodiment illustrated by FIG. 2, as gravity forces more high density material to settle around the internal base 30 of the jacket 12. The mixed density zone 22 results as a byproduct of the redistribution of the powders during the heating 104 and spinning 106 steps.

[0032] The projectile is typically spun at step 106 for about one minute after reaching the melting point of the low density material in step 104. The time of the spinning step 106 can be used to control the redistribution of the powdered metals forming the core and thus control the size of each respective zone formed thereby. Spinning for less than one minute can result in smaller high density zone 20 being formed around the inner surface 13 of the jacket 12. Spinning the projectile beyond one minute can increase the high density zone 20 and eventually causes the formation of the cavity 32 in the core 14. Further, the rotational speed utilized during the spinning step 106 may also be a means to control the redistribution of the powdered metals within the jacket. Spinning the projectile at higher RPMs will cause more of the high density powder materials to redistribute toward the inner surface of the jacket.

[0033] After the heating 104 and spinning 106 steps are complete, the projectile is tipped 108 to form the nose 28 in the low density zone 24 with a hollow point 16. Tipping 108 can be accomplished according to conventional tipping methods, e.g., by mechanically pressing the projectile upwards into a tipping die having the desired nose profile. The extruded low density material is formed into the nose 28, which is now primarily made up of the low density materials.

[0034] The projectiles 10 manufactured according to the present inventive method 100 exhibit increased flight stability. The concentration of high density materials in the high density zone 20 around the inner surface 13 of the jacket 12 produces a stabilizing effect during flight, reducing the occurrence of yaw or the rotation of the forward end of the bullet off the flight axis.

[0035] Further, the terminal ballistics for projectiles 10 manufactured according to the present inventive method 100 are significantly increased. The lower density metal forming the low density zone 24 in the projectile nose 28 readily deforms upon impact with an organic target while the copper jacket 12 enclosing the high density materials continues to penetrate. The momentum behind the projectile 10 causes the projectile to penetrate the target after the initial contact and deformation of the nose. As the projectile penetrates, the organic fluid, e.g., blood, bodily fluids, and other soft tissue, fills vacated areas within the core causing the projectile to disintegrate radially outwards in the organic target. This causes a devastating wound in the target. The individual particles of the high density material and low density material are dispersed radially outwards in the target, each serving as a micro-fragment imparting damage to the surrounding tissue. The tissue damage caused by these micro-fragments spreads well beyond the diameter of the projectile, causing an almost immediately incapacitating wound in the target.

[0036] The vacated areas within the core 14 are created by the redistribution of the core materials during steps 104 and 106 of the method 100. Due to the upward extrusion of the low density material to form the low density zone 24 at the nose 28, cavities are formed in the mixed density zone 22 and the high density zone 20 where the low density material has been extruded, e.g., microscopic cavities are formed in place of each individual low density powder particle that is melted and extruded forward. Upon impacting an organic target, these microscopic cavities are filled with the organic matter as the projectile continues through the target, eventually causing the projectile to disintegrate radially outward in the target.

[0037] Exemplary embodiments of the invention have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.

Examples

Embodiment Construction

[0018]The following disclosure presents exemplary embodiments of an improved jacketed projectile having a variable density core. The variable density core according to the present invention improves flight stability of the projectile upon being discharged from a firearm. The variable density core also significantly increases the terminal ballistics of the jacketed projectile, providing devastating damage in organic tissue and other soft target material. Terminal ballistics as used herein is understood to mean the effects and behavior of the projectile upon hitting and entering target media.

[0019]Projectiles according to the present invention can be manufactured to conform to any conventional or unconventional caliber size for ammunition projectiles, including calibers for pistol, rifle, and shotgun ammunition of civilian or military grade. Further, certain types of artillery projectiles may be manufactured in accordance with the present invention. Thus, the present inventive project...

Claims

1. A projectile, comprising:a variable density core having a high density zone, a mixed density zone, and a low density zone; anda jacket at least partially enclosing the core.

2. The projectile of claim 1, wherein the low density zone forms a nose of the projectile.

3. The projectile of claim 2, further comprising a hollow cavity defined in the low density zone to form a hollow-point nose.

4. The projectile of claim 1, wherein the high density zone extends from an inner surface of the jacket to the mixed density zone.

5. The projectile of claim 4, wherein the high density zone comprises a radially symmetrical thickness.

6. The projectile of claim 1, wherein the mixed density zone is concentrically formed around a longitudinal axis of the projectile.

7. The projectile of claim 6, wherein the mixed density zone is radially symmetrical about the longitudinal axis.

8. The projectile of claim 1, wherein the mixed density zone comprises a homogeneous mixture of a high density metal and a low density metal.

9. The projectile of claim 8, wherein the high density zone primarily comprises the high density metal.

10. The projectile of claim 8, wherein the low density zone primarily comprises the low density metal.

11. The projectile of claim 8, wherein the high density metal comprises a tungsten powder.

12. The projectile of claim 8, wherein the low density metal comprises a tin powder.

13. The projectile of claim 1, wherein the low density zone extends beyond a forward end of the jacket.

14. The projectile of claim 1, wherein the high density zone tapers from a base end toward a forward end of the jacket.

15. A method for manufacturing an improved jacketed projectile, comprising:compressing two or more metal powders within a jacket to form a jacketed powder core having a hollow point nose and a longitudinal axis, wherein the two or more metal powders comprise a high density material and a low high density material;heating the jacketed powder core to a melting point of the low density material;spinning the jacketed powder core about the longitudinal axis to extrude the low density material through the hollow point nose; andtipping the jacketed powder core to reform the hollow point nose in the extruded low density material.

16. The method of claim 15, wherein the high density material comprises a tungsten metal powder.

17. The method of claim 15, wherein the low density material comprises a tin metal powder.

18. The method of claim 15, wherein the low density material has a melting point lower than a melting point of the jacket.

19. The method of claim 15, wherein the spinning step further causes the high density material to form a uniform high density zone on an inner surface of the jacket.

20. The method of claim 15, wherein the spinning step further causes formation of a central longitudinal cavity extending from a base end through the hollow point nose.

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