Abstract:
A projectile  10  for gun ammunition of a size not greater than 50 caliber comprising a solid metal jacket  82  of generally cup-shaped geometry and having a closed end  102  and an open end  88,  a core  84  formed from a mixture of metal powders, not including lead, which mixture is cold-pressed into a self-supporting compact and disposed within said jacket, the core incompletely filling the jacket, an ogive  14  having an outer surface and defined on the initially open end of said jacket, and a conical tip  122  defined on the distal end  118  of said ogive, the tip having an outer surface  22  which defines an angle with respect to the longitudinal centerline  24  of the projectile that is greater than the angle defined by the ogive with respect to the longitudinal centerline of the projectile. A method is disclosed.

Description:
RELATED APPLICATIONS 
   This application is a non-provisional application and claims priority based on Provisional Application Ser. No. 60/366,132 filed Mar. 20, 2002 entitled AMMUNITION PROJECTILE HAVING ENHANCED AERODYNAMIC PROFILE. 

   FIELD OF INVENTION 
   The present invention relates to gun ammunition and particularly to projectiles for gun ammunition. 
   BACKGROUND OF INVENTION 
   For many years, lead has been the standard metal for use in the manufacture of projectiles for gun ammunition. Lead, however, has been found to be toxic and its elimination from gun ammunition projectiles is currently in progress. Because of this long-standing reliance upon lead as the basic metal for the manufacture of gun ammunition projectiles, the art/science of manufacture of gun ammunition projectiles has languished in mediocrity. 
   Of recent vintage are gun ammunition projectiles formed from metal powders which are compacted into shaped projectiles or which are compacted and thereafter formed into shaped projectiles. There are myriad problems associated with the manufacture of projectiles employing metal powder(s) as the basic material of the projectile. One of these problems relates to the ultimate formation of a pressed powder compact into an aerodynamically acceptable projectile. 
   Commonly, in the current state of the art, pressed powder compacts, referred to often as “cores”, are loaded into a jacket, such as a cup-shaped copper metal jacket. The core in the jacket is seated against the closed end of the jacket (“core seating”), and the open end of the jacket is formed about the core and shaped to define an aerodynamically desirable leading end of the projectile. For purposes of at least partially closing the open end of the jacket while defining the desired aerodynamic shape on that end of the core/jacket combination which will become the leading end of the projectile when it is fired from a gun, the core is chosen to be shorter in length than the depth of the jacket so that there is a portion of the jacket wall adjacent the open end of the jacket which is void of core material when the seating operation has been completed. 
   Core seating takes places with the core/jacket combination being held in a die while pressure is applied axially of the core to seat the core within the closed end of the jacket, and in part, to the side wall of the jacket. Thereafter, and usually in a different die, the open end of the jacket is formed inwardly toward the longitudinal centerline of the jacket. This operation may take place in steps, and may involve more than one die, but in the end, the initially open end of the jacket is closed to the extent desired. The initially open end of the jacket may be fully closed or partially closed, in part depending upon the desired terminal ballistics of the projectile. 
   In certain projectiles, it is desired that the projectile substantially disintegrate upon striking a target, often disintegrating only after limited penetration into a target. Maximum disintegration in these projectiles is desired, including maximum disintegration of the jacket into very small fragments, and disintegration of the powder-based core into particulates which are on the order of the individual particle size of the powder employed in forming the core. 
   Disintegration of a jacketed projectile, even projectiles formed from lead cores, is known to be enhanced through the use of a “hollow point” at the leading end of the jacketed projectile. However, hollow pointed projectiles suffer from several shortcomings, such as their tendency to misfeed from magazines into the breech of a semi-automatic or automatic weapon; their relatively inefficient aerodynamic effect upon the flight of the projectile to a target; and other ill effects, all of which must be balanced against the requirement that the projectile disintegrate to the fullest extent upon striking a target. 
   SUMMARY OF INVENTION 
   In accordance with the present invention, there is provided a projectile for gun ammunition wherein the leading end of the projectile comprises an ogive geometry, and a relatively short length of the extreme distal tip of the ogive portion of the projectile is further infolded toward the centerline of the jacket by a relatively few degrees, thereby defining a tapered tip on the extreme distal end of the ogive portion of the projectile. The ogive end of the jacket, after the tipping operation, may by partially filled with core material leaving a void volume in the most distal portion of the open end of the jacket, so that there may be defined a meplat cavity proximate the partially closed end of the jacket, the cavity opening outwardly of the jacket. Optionally, the ogive end of the jacket may be essentially fully closed. 
   This “double-infolding” of the initially open end of the jacket (herein referred to as “tipping” of the ogive portion of the projectile) has been found to provide enhanced aerodynamic properties of the projectile, such as reduced resistance to movement through air, enhanced accuracy of delivery to a target, even under adverse wind conditions, and particularly enhanced disintegration of the projectile upon striking a target. The latter feature appear to take the form of an implosion of the tapered tip of the jacket in a direction inwardly and generally along the longitudinal centerline of the jacket. This implosion, as opposed to a explosive action in which the jacket disintegrates into fragments which are propelled generally radially away from the projectile, comprises movement of at least the tipped portion of the jacket inwardly of the jacket and along the longitudinal centerline of the jacket, thence into the core itself, thereby contributing to the disintegration of the core along with the remainder of the jacket. 
   Moreover, the present invention has been found to materially, 50% or greater, reduce the aerodynamic drag on the projectile over the course of its trajectory to a target. As a result, the present projectile travels from the gun to the target faster than occurs in the absence of the present invention thereby permitting the same quantity of gun powder to produce a much higher velocity, at the target because of reduced drag, hence less loss of velocity during flight of the present projectile to a target. This feature has been found to provide enhanced accuracy of delivery of the projectile at extended target distances, such as 1 minute of angle accuracy at 1000 yards, even under adverse wind conditions. No known projectile exhibits this degree of velocity retention and delivery accuracy to a target 1000 yards distance from the gun from which the projectile is fired. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is a representation of a projectile embodying various of the features of the present invention and in which the profile of the projectile has been exaggerated to better portray the features of the present invention; 
       FIG. 2  is a representation of a projectile as depicted in FIG.  1  and depicting an exaggerated enlarged different angle of deformation of the extreme distal tip of the jacket; 
       FIG. 3  depicts one embodiment of a reamer useful in one step in the method of manufacture of a die punch useful in the manufacture of the projectile of the present invention; 
       FIG. 4  depicts one embodiment of a hob useful in one step in the method of manufacture of the die punch useful in the manufacture of the projectile of the present invention; 
       FIG. 5  depicts the setup step for reaming a die punch useful in the method of manufacture of the projectile of the present invention; 
       FIG. 6  depicts the step of reaming a die punch pursuant to the setup depicted in  FIG. 4 ; 
       FIG. 7  depicts the setup step for hobbing the die punch reamed as depicted in  FIG. 5 ; 
       FIG. 8  depicts the step of hobbing a die punch pursuant to the setup depicted in  FIG. 6 ; 
       FIG. 9  depicts the formation of an ogive geometry on the leading end of a projectile in accordance with the present invention; 
       FIG. 10  depicts the formation of a tipped geometry on the ogive produced in the step depicted in  FIG. 9 ; 
       FIGS. 11-16  depict the leading end of each of a plurality of projectiles embodying various of the features of the present invention and produced pursuant to the method disclosed; 
       FIG. 17  depicts a projectile of the present invention immediately in time prior to the projectile striking a steel plate target from a direction perpendicular to the flat face of the target, 
       FIG. 18  depicts commencement of deformation of the leading end of and the commencement of the implosion reaction of the projectile of  FIG. 17  briefly following contact of the leading end of the projectile with the target of  FIG. 17 ; 
       FIG. 19  depicts the implosion of the projectile of  FIG. 17  as the projectile further deforms after striking the target; 
       FIG. 20  depicts a projectile of the present invention immediately prior to the projectile striking a glass target at an angle of about 40 degrees between the trajectory of the projectile and the planar face of the glass target; and 
       FIG. 21  depicts deformation of the projectile of  FIG. 20  as the leading end of the projectile penetrates the thickness of the glass target. 
   

   DETAILED DESCRIPTION OF INVENTION 
   Referring to  FIG. 1 , there is depicted, somewhat exaggerated for purposes of illustration, a projectile  10  including a body portion  12  of generally straight cylindrical geometry, an ogive portion  14 , and a tipped portion  16  at the extreme distal end  16  of the ogive. The tipped ogive portion of the projectile defines the leading end of the projectile when it is fired from a weapon. As noted the angularity of the tipped portion  16  is somewhat exaggerated for illustration purposes. 
     FIG. 2  depicts an enlarged and even more exaggerated embodiment of the leading end of the projectile depicted in FIG.  1 . In  FIG. 2 , it may be seen that the extended side surface line  20  of the side  22  of the tip defines an angle “X 31   relative to the longitudinal centerline  24  of the projectile. The depth “d” of the tip is measured from distal end  26  of the jacket  28  of the projectile inwardly along the longitudinal centerline of the projectile. 
   The projectile of  FIG. 2  comprises a metal, preferably copper, jacket  28  which houses a quantity of a mixture of two or more metal powders  30  and a plug  32 , commonly of a hollow hemispherical geometry formed from a disc, preferably of a metal such as tin, as described in U.S. Pat. Nos. 5,789,698 and 6,371,029, the entirely of both of which are incorporated herein by reference. 
   In accordance with one method for the production of a tipped ogive of a projectile of the present invention, there is employed a reamer  40  such as depicted in  FIG. 3  having a conical cutting end  42  for the milling of a conical depression  44  in the end of a die punch  46  (see FIG.  7 ). The extension of the outer wall  43  of the depicted conical cutting end  42  of the reamer defines a 45 degree angle “A” with respect to the longitudinal centerline  47  of the mounting shank  48  of the reamer. Preferably a two-fluted  50  reamer is employed. 
   Referring to  FIGS. 4-8 , Further, in the production process the conical depression  44  in the die punch  46 , following the reaming of the depression  44 , the depression is “hobbed” with a hob  52  such as depicted in  FIGS. 4 ,  7  and  8 . The depicted hob comprises a mounting shank  54  and a conical head  56  which, after its initial formation is heat treated and polished to provide maximum hardness and smoothness of the conical head. The extension of the outer wall  58  of the hob defines an angle “B” of 45 degrees with respect to the longitudinal centerline  68  of the hob. The reaming operation is very precise and produces a very smooth finish on the inside wall  62  of the conical depression  44 . However, the present inventors have found that a “mirror” finish is preferred on the inner wall of the depression, hence as seen in  FIGS. 7 and 8 , following reaming of the depression, the reamed die punch is placed in the cylindrical cavity  63  of a die  64  with the outer wall  66  of the die punch in intimate engagement with the inner wall of the die cavity such that the die punch can not expand radially to any material extent. Thereupon the hob is positioned within the conical depression and axial pressure is applied along the longitudinal centerline of the hob to force the hob into the conical depression and thereby smooth out any cut marks or the like which the reamer may have developed on the inner wall of the conical depression. 
   The die punch  46 , having its hobbed conical depression  44  in one end  70  thereof, is employed in the formation of a tipped ogive of the present invention as depicted in  FIGS. 9 and 10 . In  FIG. 9 , there is depicted the operation of forming an ogive on a powder-based jacketed projectile  80 . The depicted projectile comprises an outer metal jacket  82  which houses a core  84  formed from a quantity of cold compressed mixture of metal powders and a plug  86  disposed between the powder based core and the open end  88  of the jacket. To form the completed non-tipped ogive depicted in  FIG. 9 , the open end of the jacket is inserted into the cavity  90  of a die  92  having the desired ogive contour defined in a closed end  94  of the cavity. An extraction punch  96  is employed to close the ogive end of the die cavity and to extract the projectile from the die after the ogive is formed. A punch  98  inserted into that end  100  of the die cavity opposite the ogive end is employed to apply axial pressure against the closed end  102  of the jacketed projectile to urge the projectile into the ogive defining end of the die cavity to the extent desired for forming the ogive portion of the projectile. The projectile is thereafter ejected from the die. 
   Tipping of the ogive portion of the projectile of  FIG. 9  is depicted in FIG.  10 . As shown, in one embodiment of this procedure, the die punch  46  formed as depicted in  FIGS. 5-8  is inserted into the cavity  104  of a die  106 . Thereupon, the ogive end of the projectile is positioned in the conical depression of the die punch  46 , following which axial pressure is applied by means of a further punch  108  to the closed end  102  of the projectile to urge the projectile toward the die punch  46 . In one embodiment, the die punch  46  is unrestrained against longitudinal movement in the direction of the longitudinal centerline  110  of the die punch, within the cavity of the die  106  so that the projectile, acting against the end  112  of the die punch  46  can push the die punch upwardly as seen in  FIG. 10  until the flat opposite end  114  of the die punch engages a rigidly mounted stop  116 . At this position of the die punch, further pressure is applied to the closed end  102  of the projectile to cause the distal end  118  of the ogive portion  120  of the projectile to conform to the inner conical geometry of the depression  44  in the end of the die punch  46 , thereby forming a conical tip  122  (see  FIG. 11 ) on the extreme distal end  118  of the ogive portion of the projectile. Through selection of the relative position of the stop and the flat end of the die punch, and/or the limit of axial movement of the further punch, the present inventors select the depth to which the ogive portion of the projectile enters the conical depression in the die punch, hence the depth of the tip which is defined on the ogive portion of the projectile. This same selection procedure, along with the selection of the angles “A” and “B” of the reamer and hob, respectively, further provides for the extent to which the initially open end of the ogive portion of the projectile is further closed. This latter feature of the present invention is depicted in  FIGS. 11-16  wherein there are depicted several possible combinations of tip depth and the angle of the tip wall relative to the longitudinal centerline of the projectile, as well as several degrees of closing of the extreme distal end of the ogive portion of the projectile. 
   The following Table presents representative combinations of tip depth and the size of the obtainable opening remaining in the end of the jacket of the projectile following the tipping operation: 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE I 
             
             
                 
                 
             
             
                 
                 
                 
                 
               Opening Size (Dia.) 
             
             
                 
               Caliber 
               Ogive 
               Depth (inch) 
               (inch) 
             
             
                 
                 
             
           
           
             
                 
             
           
        
         
             
                 
               .223 
               5 
               .003 
               .007 
             
             
                 
               .223 
               7 
               ˜.006  
               &lt;.001  
             
             
                 
               .223 
               7 
               .010 
               .005 
             
             
                 
               .223 
               12 
               .004 
               .003 
             
             
                 
               .308 Win 
               7 
               .010 
               .004 
             
             
                 
               .308 Win 
               8 
               .010 
               .002 
             
             
                 
                 
             
           
        
       
     
   
   It is noted from Table I that the choice of depth of the tip, for a given ogive, may be employed to select the extent to which the open end of the ogive is closed. The size of such opening is generally chosen as a function of the desired terminal ballistics of the projectile as will be recognized by one skilled in the art. 
   For most caliber projectiles (50 caliber or smaller calibers), the angle “A” for the reamer may vary between about 2 degrees and about 45 degrees. In all instances, the angle “B” of the hob is to be the same as the angle of the reamer. Depths of the tip may vary between about 0.003 inch and about 0.4 inch. Tips having angular and depth parameters outside these ranges may be employed, but commonly projectiles having such outside parameters do not perform satisfactorily with respect to one or the other of the desired terminal ballistics or accuracy of delivery of the projectile to a target, especially at the longer ranges, such as 1000 yards or more. 
   As noted, projectiles having a tipped ogive portion as disclosed hereinabove, when fired from a gun, exhibited unexpectedly enhanced flight to a target, both in time of flight and accuracy of delivery. Moreover, the terminal ballistics of the projectile upon striking a target were substantially enhanced with respect to the frangibility of the projectile. Notably, the jacket portion of the projectile disintegrated into minute particulates whose energy was expended almost immediately, hence they did not present a possible danger to collateral targets as is known to exist for projectiles of the prior art. Moreover, the wound cavity developed by the imploding of the tipped portion of the projectile into the powdered core of the projectile was noted to be substantially enhanced as compared to wound cavities produced by like projectiles fired from like guns under like conditions. 
   Referring to  FIGS. 17-19 , tests involving firing of projectiles  10  of the present invention into a steel plate target  130  from a direction  132  perpendicular to the flat face  134  of the target indicate that the tipped ogive  136  on the leading end of the projectiles causes the tipped portion  138  of the extreme distal end  140  of the projectile to implode into the interior  142  of the projectile. This implosion reaction appears to proceed initially as depicted by the arrows of FIG.  18 . Thereafter, it further appears that the projectile, including the powder-based core and the jacket, disintegrates and explodes into a very large number of small particulates which, because of their small size rapidly loose their kinetic energy and fall harmless away from the target. At distances of less than three feet from the face of the steel plate target, no harmful particulates of the projectile are evident. 
   As depicted in  FIGS. 20 and 21 , it has also been found that the tipped ogive projectiles of the present invention, when striking a glass target  150 , such as the windshield of a motor vehicle, at an angle “C” of as much as about 40 degrees, penetrate and pass through the glass target in a straight line (see FIG.  21 ), as opposed to deflection of the projectile from its trajectory by reason of it passing through the glass target as is well known with respect to projectiles of the prior art. 
   Whereas specific examples and embodiments of the present invention have been described and/or depicted, it will be understood by one skilled in the art that various changes and/or modifications may be made in the presently disclosed invention without departing from the scope of the invention.