Patent Publication Number: US-7900561-B2

Title: Reduced friction projectile

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of and claims priority to pending U.S. patent application Ser. No. 11/255,261, entitled: “Firearms Projectile,” filed Oct. 21, 2005 by the same inventor, which application is hereby incorporated by reference into this application. This application also claims priority to U.S. Provisional Patent Application No. 61/326,809, entitled “Reduced Friction Projectile,” filed Apr. 22, 2010 by the same inventor, which application is hereby incorporated by reference into this application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates, generally, to the art of projectiles. More particularly, it relates to a projectile that is crimped at preselected locations along its length when fired. 
     2. Description of the Prior Art 
     Conventional projectiles engage the lands and grooves formed in a gun barrel along substantially the entire length of the projectile. About the only part of the projectile that does not engage the rifling is the ogive-shaped leading tip of the projectile. 
     The art has not recognized that the substantially full-length engagement of a projectile and rifling reduces the kinetic energy of the projectile. Nor has it recognized that the friction created by such substantially full-length engagement causes the barrel to heat up with repeated firing. Nor has the art recognized that such substantially full-length engagement leads to deformation of the projectile by the rifling in a way that is unpredictable. Such unpredictable deformation leads to unpredictable alterations in behavior of the projectile. 
     Thus there is a need for a projectile that has less contact with rifling vis a vis a conventional projectile so that the kinetic energy of the projectile can be increased. 
     There is a need as well for a projectile that has less contact with rifling to reduce friction-related heat build-up in a barrel caused by repeated firing without sacrificing spin imparted by the rifling. 
     There is also a need for a projectile that deforms in a predictable way when fired. 
     However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the art how the identified needs could be met. 
     SUMMARY OF THE INVENTION 
     The long-standing but heretofore unfulfilled need for a projectile not subject to the limitations of prior art projectiles is now met by a new, useful, and non-obvious invention. 
     The novel projectile includes a leading part formed by a tip having a generally ogive shape. A tip base of cylindrical construction is formed integrally with the tip and has a reduced diameter relative to a trailing end of the tip so that a first annular shoulder is formed where the trailing end of the tip meets the leading end of the tip base. A leading rod is formed integrally with the tip base and has a reduced diameter relative to the diameter of the tip base so that a second annular shoulder is formed where a trailing end of the tip base meets the leading end of the leading rod. 
     The novel projectile further includes a trailing part formed by a main base. A truncate base of cylindrical construction is formed integrally with a leading end of the main base and has a reduced diameter relative to the diameter of the leading end of the main base so that a third annular shoulder is formed where the leading end of the main base meets the trailing end of the truncate base. A trailing rod is formed integrally with a leading end of the truncate base and has a reduced diameter relative to the diameter of the truncate base so that a fourth annular shoulder is formed where the truncate base meets the trailing rod. 
     A cylindrical interface has a leading end that abuttingly engages the first annular shoulder and a trailing end that abuttingly engages the third annular shoulder. The cylindrical interface has a leading extent supported by the extent of the tip base, a trailing end supported by the extent of the truncate base, and a medial extent unsupported by said leading rod and said trailing rod. 
     The unsupported medial extent of the cylindrical interface is therefore deformed radially inwardly by lands in a barrel when the projectile is fired. The leading and trailing ends of the cylindrical interface maintain contact with the lands and the medial extent does not, thereby reducing friction between the projectile and the barrel without sacrificing the spin of the projectile imparted by the lands and grooves. 
     The leading rod has a flat trailing end that abuts a flat leading end of the trailing rod when the leading end of the cylindrical interface abuts the first annular shoulder and the trailing end of the cylindrical interface abuts the third annular shoulder. 
     The leading rod and the trailing rod share a common cylindrical configuration so that the cylindrical interface conforms to such cylindrical configuration along the unsupported medial extent thereof when the medial extent is deformed by the lands and grooves. 
     In a second embodiment, a first plurality of radially outwardly projecting elongate ribs is formed in the leading rod in equidistantly and circumferentially spaced apart relation to one another and in parallel relation to a longitudinal axis of symmetry of the projectile. A second plurality of radially outwardly projecting elongate ribs is formed in the trailing rod in equidistantly and circumferentially spaced apart relation to one another and in parallel relation to the longitudinal axis of symmetry of the projectile. 
     The first and second plurality of elongate ribs are disposed in supporting relation to the cylindrical interface along its entire extent so that when the lands supply radially inwardly directed crushing forces, the cylindrical interface is deformed radially inwardly in unsupported valleys between said elongate ribs. 
     In a third embodiment, the leading rod and the trailing rod have a hexagonal cross-sectional configuration. When the lands supply radially inwardly directed crushing forces, the cylindrical interface is deformed radially inwardly until it conforms along its length to the hexagonal shape of the leading and trailing rods. 
     In a fourth embodiment, the leading rod and the trailing rod have a fluted cross-sectional configuration. When the lands supply radially inwardly directed crushing forces, the cylindrical interface is deformed radially inwardly until it conforms along its length to the fluted shape of the leading and trailing rods. 
     Thus it is understood that the respective cross-sectional configurations of the leading and trailing rods may be provided in any predetermined geometrical configuration and that the cylindrical interface will be deformed by the lands upon projectile firing so that the cylindrical interface conforms to the predetermined geometrical configuration of the leading and trailing rods. This advantageously reduces the frictional contact between the cylindrical interface and the rifling without affecting the contact between the leading and trailing parts of the projectile and the rifling. Thus, spin is still imparted to the projectile but the friction created by the travel of the projectile through the barrel is substantially reduced. 
     An important object of the invention is to reduce the friction between a projectile and the interior of a gun barrel to increase the kinetic energy of the projectile, to reduce heat build-up in the barrel caused by repeated rapid firing, and to deform the projectile in a predictable, consistent way. 
     These and other important objects, advantages, and features of the invention will become clear as this description proceeds. 
     The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which: 
         FIG. 1  is an exploded perspective view of a first embodiment of the invention including a leading part, a trailing part, and a cylindrical interface that interconnects the leading and trailing parts to one another; 
         FIG. 2  is an assembled view of the parts depicted in  FIG. 1  prior to crimping of the leading end of the cylindrical interface; 
         FIG. 3  is a perspective view of the embodiment of  FIG. 1  after crimping of the leading end of the interface; 
         FIG. 4  is a perspective view of the first embodiment when positioned with a rifle barrel that is cut-away to enable viewing of the novel projectile; 
         FIG. 5  is a perspective view like that of  FIG. 5  but depicting an elongate crimp produced in the cylindrical interface as a result of firing the rifle; 
         FIG. 6A  is an exploded perspective view of a second embodiment; 
         FIG. 6B  is an exploded perspective view of a third embodiment; 
         FIG. 6C  is an exploded perspective view of a fourth embodiment; and 
         FIG. 6D  is an exploded perspective view of a fifth embodiment. 
         FIGS. 7A-7C  are views of a sixth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIG. 1 , it will there be seen that an exploded perspective view of the novel projectile is denoted as a whole by the reference numeral  10 . 
     Projectile  10  includes a leading part formed by nose cone or tip  12  having a generally ogive shape. Tip base  14  of solid cylindrical construction is integrally formed with tip  12  and has a reduced diameter so that first annular shoulder  16  is formed where the trailing end of tip  12  meets the leading end of tip base  14 . Leading rod  18  is integrally formed with tip base  14  and has a reduced diameter so that second annular shoulder  20  is formed where the trailing end of tip base  14  meets the leading end of leading rod  18 . 
     Projectile  10  further includes a trailing part formed by frusto-conical main base  22 . Truncate base  24  of solid cylindrical construction is integrally formed with frusto-conical main base  22  and has a reduced diameter relative to the leading end of said main base so that third annular shoulder  26  is formed where the leading end of frusto-conical main base  22  meets the trailing end of truncate base  24 . Trailing rod  28  is formed integrally with a leading end of said truncate base and has a reduced diameter relative to said leading end of said main base so that fourth annular shoulder  30  is formed where the leading end of truncate base  24  meets the trailing end of trailing rod  28 . 
     Cylindrical interface  32  includes leading end  32   a  that abuttingly engages first shoulder  16  and a trailing end that abuttingly engages third shoulder  26 . 
     As indicated in  FIG. 2  by the radially inwardly directed arrows, an annular crimp is formed at the leading end of cylindrical interface  32  to produce the finished construction depicted in  FIG. 3  where the leading end of cylindrical interface  32  is substantially flush with the trailing end of tip  12 . The internal diameter of cylindrical interface  32  is greater than the external diameter of the trailing end of tip  12  because cylindrical interface  32  ensleeves tip  12  as said cylindrical interface is introduced into its  FIG. 2  position as indicated in  FIG. 6D . 
     The flat trailing end of leading rod  18  abuts the flat leading end of trailing rod  28  when the leading end of cylindrical interface  32  abuts first annular shoulder  16  and the trailing end of cylindrical interface  21  abuts third annular shoulder  26 , as indicated in  FIGS. 2 ,  3 , and  5 . 
     As depicted in  FIGS. 2 and 3 , cylindrical interstitial space  34  is defined radially inwardly of cylindrical interface  32  and radially outwardly of leading rod  18  and trailing rod  28 . Accordingly, cylindrical interface  32  is supported at its leading extent by tip base  14  and at its trailing extent by truncate base  24 . Therefore, cylindrical interface is unsupported along the extent thereof that is positioned radially outwardly of leading rod  18  and trailing rod  28 . However, said leading rod  18  and said trailing rod  28  provide a limit beyond which cylindrical interface cannot be deformed if subjected to radially inwardly directed forces. 
       FIG. 4  depicts novel projectile  10  when positioned in a rifle barrel. The rifling is denoted  36 . 
     When projectile  10  is launched, as indicated by starburst  38  in  FIG. 5 , the radially inwardly projecting helical lands of rifling  36  exert a radially inwardly directed force on cylindrical interface  32  along its entire extent as it travels through the bore of the firearm. However, only the unsupported part of said cylindrical interface  32  is crushed by such forces as depicted in  FIG. 5  and the extent of the crushing is limited by the presence of leading rod  18  and trailing rod  28  as aforesaid. 
     Advantageously, the leading extent of cylindrical interface  32  supported by tip base  14  and the trailing extent of cylindrical interface  32  supported by truncate base  24  are not displaced radially inwardly and thus retain contact with the lands so that spin is imparted to the projectile as desired. Also advantageously, the deformed or crushed extent of cylindrical interface  32  is disengaged from said lands, thereby substantially reducing friction between said cylindrical interface and the lands of the rifling. The reduced friction enables projectile  10  to escape from the barrel with increased velocity without sacrificing the beneficial aspects of the lands, i.e., without loss of spin. 
     Leading rod  18  and trailing rod  28  are depicted as being cylindrical in  FIGS. 1 through 5 . It should therefore be understood that the crushed or deformed extent of cylindrical interface  32  conforms to such cylindrical shape. As best understood in connection with  FIGS. 6A-D , the invention is not limited to such cylindrical shape. 
     In  FIG. 6A , for example, a first plurality of radially outwardly projecting elongate ribs  18   a  are formed in trailing rod  18  in equidistantly and circumferentially spaced apart relation to one another and in parallel relation to a longitudinal axis of symmetry of projectile  10 . A second plurality of radially outwardly projecting elongate ribs  28   a  are formed in trailing rod  28  in equidistantly and circumferentially spaced apart relation to one another and in parallel relation to a longitudinal axis of symmetry of projectile  10 . These ribs support cylindrical interface  32  so that when the lands supply the radially inwardly directed crushing forces, only the elongate parts of cylindrical interface  32  between said ribs are unsupported and therefore deformed in a radially inward direction. This reduces the friction between projectile  10  and the interior of the barrel but it increases the surface area of cylindrical interface  32  that remains in contact with the spin-imparting lands vis a vis the surface area of the first embodiment. 
     Leading rod  18  and trailing rod  28  have a hexagonal configuration in the embodiment of  FIG. 6B . The crushed or deformed section of cylindrical interface  32  will thus have a hexagonal shape as well. As in the embodiment of  FIG. 6A , this reduces friction between projectile  10  and the interior of the barrel while maintaining contact at six (6) elongate linear extents with the spin-imparting lands. Leading rod  18  and trailing rod  28  may also have triangular, square, pentagonal and other predetermined geometrical cross-sectional configurations as well in order to both reduce friction while maintaining contact with the lands. 
     A configuration having eight (8) contacts with linear extent is depicted in  FIG. 6C . 
     In the embodiment of  FIG. 6D , leading rod  18  and trailing rod  28  are integrally formed with one another to form resulting rod  40 . Rod  40  is fluted like the embodiment of  FIG. 6C  and therefore has eight (8) contacts with linear extent. In all other respects, it provides the same benefits as the other embodiments. 
     The projectile of  FIG. 6D  is easy to manufacture. Cylindrical interface  32  is slid over tip  12  into position as indicated by the single-headed directional arrow and the leading end of said cylindrical interface  32  is then crimped as mentioned above in connection with  FIG. 1 . 
     In yet another alternative embodiment shown in  FIGS. 7A-C , rear annular shoulder  42   a  is formed forward of base  22  leaving first interstitial gap  44   a . Forward annular shoulder  42   b  is formed forward of rear annular shoulder  42   a  and aft of tip  12  forming second interstitial gap  44   b  between forward annular shoulder  42   b  and rear annular shoulder  42   a . A third interstitial gap  44   c  is formed between forward annular shoulder  42   b  and tip  12 . While annular shoulders  42   a - b  are a preferred embodiment, it is within the scope of the invention that additional annular shoulders may be formed.  FIG. 7B  shows cylindrical interface  32  slide over projective an crimped about tip  12 . Interstitial gaps  44   a - c  are noted.  FIG. 7C  shows cylindrical interface  32  compressed by the force of the propellant within the barrel (not shown) to follow the contours of annular shoulders  42   a - b . It should be noted that the height of annular should  42   a - b  and interstitial gaps  44   a - c  are not necessarily drawn to scale but to be illustrative of the inventive concept. It should also be noted that  FIGS. 7A-C  show a unitary projectile but it is within the scope of the invention to employ annular shoulders  42   a - b  for a multi-component projectile as well as illustrated in  FIGS. 1-5  and  6 A-C. 
     It should be noted that a preferred dimension for the interstitial space (the gap measured radially) is computed by the difference between the diameter of the rifling grooves and the rifling lands minus approximately one one-thousandth of an inch. The difference between the diameter of the rifling grooves and the rifling lands is indicative of the compressive reduction of projectile diameter. However, the interstitial space should be somewhat less than this value (hence one one-thousandth of an inch) to ensure that the interface continues to engage the rifling of the barrel so that spin is still imparted on the projectile. The value of one one-thousandth of an inch may be varied wherein a greater value may ensure more engagement with the rifling but would also impart more friction and wear. Lesser values may reduce friction and wear on the barrel but could ultimately sacrifice flight-stabilizing spin. 
     It will thus be seen that the objects set forth above, and those made apparent from the foregoing description, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.