Patent Publication Number: US-2006011092-A1

Title: High velocity ammunition system and firearm

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in U.S. Provisional Patent Application No. 60/574,246, filed May 25, 2004. 
    
    
     FIELD OF THE INVENTION  
      This invention relates in general to high velocity firearms and associated high velocity ammunition and deals more specifically with improvements in hand guns, particularly revolvers and high velocity ammunition for such firearms.  
     BACKGROUND OF THE INVENTION  
      Bottleneck ammunition is well known in the firearm art and is usually used in rifles, particularly those of bolt-action type, and other long guns. A typical bottleneck ammunition cartridge includes an axially elongated cartridge case which has a cylindrical forward end portion within which a projectile or bullet is supported, a generally cylindrical rear end portion which has a base and a major diameter substantially greater than the diameter of the forward end portion, which carries the projectile. A neck-down portion disposed intermediate the front and rear portions of the cartridge case provide smooth transition there between. This bottleneck cartridge case configuration allows for the provision of a relatively large amount of a propellant charge to be contained within the rear portion of the case as is necessary for the attainment of a high muzzle velocity. The term “high velocity”, as hereinafter used, is intended to mean a muzzle velocity in excess of about 2,500 feet per second (ft./sec.).  
      Previous attempts to use bottleneck type cartridges with revolvers have proven generally unsuccessful. Such cartridges tend to expand when fired and drive the spent cartridge case in a rearward direction and toward the standing breech or bolster surface on the revolver frame at the immediate rear of the revolver cylinder. This condition may be attributed to some of the force generated by the gases of explosion in firing the cartridge being dissipated against the inner surfaces of the cylindrical and neck-down portions of the case, resulting in a net force vectoring the cartridge case in a rearward direction. Consequently, rotation of the revolver cylinder is likely to be inhibited if not precluded. It has also been found that if none of the cartridge cases are driven against the revolver frame with sufficient force to inhibit or preclude proper cylinder indexing rotation and or movement of the cylinder between open and closed positions relative to the revolver frame, extraction of the spent cases may be only marginally satisfactory if not totally unacceptable.  
      It is the general aim of the present invention to provide and improve ammunition system to allow for sufficient propellant charge or powder quantity to generate the energy necessary to achieve desired velocities while retaining the desired consistent functional characteristics of the firearm with which the ammunition is used.  
      It is a further aim of the present invention to provide improved handguns and particularly revolvers for effectively employing ammunition of the present invention while assuring consistent trouble free functionality of the action of the gun in which the cartridge is fired.  
     SUMMARY OF THE INVENTION  
      In accordance with the present invention, a firearm for use with a round of high velocity ammunition also embodying the invention and having a projectile matching the caliber of the firearm bore and for engaging rifling in the bore. The projectile is carried by a sabot mounted within a diametrically enlarged cartridge case containing a propellant charge capable of propelling the projectile from the firearm at a high muzzle velocity. Further, and in accordance with the invention, the firearm has a chamber configured and dimensioned to cooperate with the cartridge case and the projectile to confine the nonmetallic sabot so that it will be compressed to a point of fragmentation and fragmetized by the dynamic forces generated by expansion of the gases of explosion when a high velocity propellant charge contained within the diametrically enlarged cartridge case. When the firearm is discharged, dynamic forces generated by the substantially instantaneous expansion of the gases of explosion compress and fragmentize the sabot. The sabot fragments, entrained in the escaping gases of explosion, travel through the firearm bore and escape from the firearm at its muzzle end. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a side elevational view of a revolver embodying the present invention and utilizing the ammunition system of the present invention.  
       FIG. 2  is a fragmentary side elevational view of the revolver of  FIG. 1  shown with the cylinder in open position.  
       FIG. 3  is a sectional view taken along the line  3 - 3  of  FIG. 2 .  
       FIG. 4  is an exploded perspective view of the revolver cylinder and shows the cylinder support yoke and the extractor mechanism.  
       FIG. 5  is a somewhat enlarged rear view of the revolver cylinder.  
       FIG. 6  is a somewhat enlarged rear elevational view of the extractor.  
       FIG. 7  is a somewhat enlarged schematic view illustrating the cylinder indexing mechanism.  
       FIG. 8  is a somewhat enlarged axial sectional view through a cartridge embodying the ammunition system of the present invention.  
       FIG. 9  is a sectional view taken along the line  9 - 9  of  FIG. 8 .  
       FIG. 10  is a sectional view taken along the line  10 - 10  of  FIG. 8 .  
       FIG. 11  is a perspective view of the sabot shown in  FIGS. 8-10 .  
       FIG. 12  is an axial sectional view through a revolver cylinder  12  chambered in accordance with the invention and shown with cartridges embodying the present invention in the chargeholes of the cylinder.  
       FIG. 13  is similar to  FIG. 8 , but shows another cartridge embodying the ammunition system of the present invention.  
       FIG. 14  is an axial sectional view taken along the line  14 - 14  of  FIG. 13 .  
       FIG. 15  is a sectional view taken along the line  15 - 15  of  FIG. 13 .  
       FIG. 16  is a perspective view of the sabot shown in  FIGS. 13-15 .  
       FIG. 17  is an axial sectional view through yet another cartridge embodying the ammunition system of the present invention.  
       FIG. 18  is a sectional view taken along the line  18 - 18  of  FIG. 17 .  
       FIG. 19  is a sectional view taken along the line  19 - 19  of  FIG. 17 .  
       FIG. 20  shows another revolver cylinder for use with the revolver of  FIG. 1  to fire cartridges shown in  FIGS. 17-19 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Turning now to the drawings, a high velocity firearm or revolver embodying the present invention and particularly adapted to fire high velocity ammunition embodying the invention is shown in  FIG. 1  and indicated generally by the reference numeral  10 . The illustrated firearm  10  is a modified Model 500 Smith &amp; Wesson Revolver, manufactured by Smith &amp; Wesson Corp., Springfield Mass., assignee of the present invention, and includes a frame  12  and an axially elongated barrel  14  mounted in fixed position and projecting in and axially forward direction from the frame. The barrel defines a rifled bore,  16  which extends axially through it from a breech or rear end to a forward or muzzle end. The revolver  10  further include a rotary cylinder  18 , which is supported for indexable rotation relative to the frame has a circumaxially series of equangularly spaced apart chargeholes  20 , 20  extending therethrough. The chargeholes are chambered in accordance with the present invention to receive high velocity ammunition embodying the present invention, as will be hereinafter further discussed.  
      Referring now particularly to  FIGS. 2 and 3 . The cylinder  18 , shown somewhat schematically, is supported on the frame  12  by a yoke  22  to pivot relative to the frame and about an axis  24  between a closed or firing position wherein the cylinder is disposed within an opening  25  defined by the frame and shown in  FIG. 1 , and an open position, shown in  FIGS. 2 and 3 , wherein the cylinder is disposed generally adjacent the left side of the frame  12 . In the cylinder open position extracted spent cartridges may be dumped from the cylinder to permit cylinder reloading. A cylinder release mechanism (not shown) normally biased to a cylinder retaining position secures the cylinder  18  in closed position within the frame opening  25 , as previously discussed. A thumb piece  26  located on the left side of the frame  12  rearward of the cylinder  18  is operable to release the cylinder from closed position and allow it to be rotated out of the frame opening  25  and to open position. Further disclosure of a cylinder supporting yoke and the manner in which a revolver cylinder may be supported on a revolver frame for pivotal movement between open and closed positions is found in U.S. Pat. No. 1,181,417 to Wesson, which is hereby adopted by reference as part of the present disclosure.  
      The revolver  10  has an extractor of conventional type for removing spent cartridge cases from the charge holes or chambers  20 , 20  of the revolver cylinder  18  as shown in  FIG. 4 . The extractor, indicated generally at  28  comprises a star or extractor plate  30  mounted in a recess in the rear surface of the cylinder  18 . The extractor plate  30  is mounted on the rear end of a tubular stem  32  and has a plurality of radially extending arms  34 , 34  equangularly spaced about the axis of the stem  32  and defining between each adjacent pair of arms a parti-cylindrical surface which conforms with the inner-cylindrical surface portion of one of the cartridge chambers  20  formed in the revolver cylinder  18 . The extractor plate  30  also includes, on its rear surface, a rearwardly projecting ring or annulus  29  on which there are formed a plurality of ratchets (not shown), equal in number to the chambers  20 , 20 , for a purpose which will be hereinafter further explained. The depth of the recess within which the extractor plate  30  is received is substantially equal to the thickness of the extractor plate, so that the rearwardly facing surfaces of the extractor plate and the cylinder  18  are disposed within a substantially common radial plane when the cylinder  18  is retained in closed or firing position. In the latter position the curved inner edges on the extractor plate, defined by the arms  34 , 34  are disposed forward of a rim on each of the cartridge cases disposed within the cylinder  18 . After the cartridges in the cylinder have been fired, the cylinder retaining mechanism has been operated, and the cylinder has been moved out of the frame opening  25  and to it&#39;s open position, a rearward thrust on the extractor or stem rod will cause the spent cartridge, cartridges to be pushed rearwardly and out of their respectively associated charge holes for dumping to permit reloading.  
      A more complete disclosure of a presently preferred extractor mechanism for use in practicing the present invention is found in my earlier U.S. Pat. No. 5,218,148, which is hereby adopted by reference as part of this disclosure.  
      The illustrated revolver, which embodies the present invention, also includes a conventional cylinder indexing mechanism shown somewhat schematically in  FIG. 7  and indicated generally by the reference numeral  36 . The indexing mechanism includes a trigger  38  for operating a firing mechanism (not shown). The trigger  38  is pivotally supported on the frame  12  by a pivot pin  40 . A hand  42  pivotally connected to the trigger is configured to cooperate with the ratchet, one of the cylinder chambers  20 , 20  into coaxial alignment with the bore each time the trigger is operated. As each of the chambers  20 , 20  is indexed into alignment with the barrel a latch  42  associated with the trigger mechanism moves into latching engagement within an associated keeper opening in the cylinder to secure the cylinder in its position during the firing cycle. A more complete disclosure of such an indexing mechanism is found in U.S. Pat. No. 6,571,502 to Mikuta, assigned to the assignee of the present invention and hereby adopted by reference as part of the present disclosure.  
      It is anticipated that the ammunition system of the present invention will prove suitable for use with a wide variety of types of firearms. A revolver having operational characteristics which particularly suitable for use with ammunition in accordance with the present invention having been hereinbefore described ammunition embodying the present invention will now be considered and with particular reference to the inventive concepts of the firearm chamber within which it is received.  
      Referring now particularly to  FIGS. 8-10  a cartridge or round of ammunition embodying the ammunition to system of the present invention is indicated generally by the reference numeral  50 . The illustrated cartridge  50  essentially comprises a case  52  a projectile or bullet  54  a sabot  56  for positioning and supporting the projectile within the case and a predetermined quantity of a propellant or outer charge suitable for imparting to the projectile a muzzle velocity in excess of 2,500 (ft./sec.).  
      The invention is preferably practiced with metal, rimed cartridges of centerfire type the case being preferably fabricated from brass. The case may be characterized as an axially elongated generally cylindrical thin walled shell which includes a radially disposed base  60  at its rear end percussion cap or primer is mounted centrally within a rearwardly open recess in the base wall and communicates with the interior of the case through a central bore opening  62 . The major diameter of the case ranges from about 0.4 in. to about 0.5 in.  
      The invention maybe practiced with projectiles of various kinds. The presently preferred projectile  54  has an ogival head portion indicated at  64  which forms a transition with a generally cylindrical trailing portion  66  having an axial length approximately equal to the length of the end portion  64 . In accordance with the invention, the projectile  54  is matched to the caliber of the firearm with which it is to be used and it is intended that the projectile engage the bore rifling in a conventional manner. Preferably, the present projectile has a major diameter ranging from about 0.264 in. to about 0.308 in.  
      A sabot is conventionally used as a carrier for a sub-caliber projectile engages the bore or rifling of a firearm from which the projectile is fixed. However, in accordance with the present invention, the only function of the sabot  56  is to position and support the relatively small diameter projectile in coaxial alignment with the substantially larger diameter case  52 . The present sabot, is preferably molded otherwise formed from a somewhat resilient lightweight non metalic plastic material. It has an axially elongated generally cylindrical body with a coaxial stepped bore  68 . The bore  68  has a generally cylindrical front-end portion  70  a rear-end portion  72  of somewhat smaller diameter and a radially disposed annular shoulder  74  which forms a transitional surface between the front portion and the dramatically reduced rear portions of the sabot bore  68 . Generally radially disposed annular surfaces  76  and  78  coaxially surround the front and rear bore portions  70  and  72 , substantially as shown. The axial length of the front portion  70  is substantially equal to the axial length of the projectile trailing portion  66  which is received in press fit within the front portion  70  of the sabot bore whereby the projectile  54  is located relative to sabot  56 . The sabot  56  is, in turn and with the rear surface of the projectile in engagement with the shoulder  74  of the sabot received within the case  52  through the mouth thereof and is disposed in press fit engagement with the case. The forward end portion of the case which defines the mouth thereof is crimped into engagement with the sabot proximate the frontal bearing surface  76  of the sabot. Thus, the latter radially disposed frontal surface is exposed at the mouth of the cartridge for complementary abutting engagement with the transitional abutment surface of the chamber  20 .  
      Referring now to  FIG. 12  the cartridge  50  is shown in its firing position within an associated chamber  20  of the revolver cylinder  18 . In accordance with the invention the chamber  20  has a cylindrical stepped bore extending through it. The bore  20  has a cylindrical forward end portion  80  sized to receive the projectile  54  therethrough and provide smooth transition into the barrel bore. The substantially larger rear portion of the chamber  20 , indicated by the numeral  82  is sized to receive the cartridge case in a conventional manner. A generally radially disposed and rearwardly facing abutment surface  84  forms a transition between the forward and rear portions of the chamber  20 .  
      When the cartridge  50  is loaded in an associated cylinder chamber  20  the radial bearing surface at the forward-end of the sabot, is disposed in abutting engagement with the rearwardly facing annular abutment surface of the chamber.  
      When the round  50  is fired the substantially instantaneous increase in pressure generates dynamic forces acting upon the exposed rear surfaces of the projectile  54  and the sabot  56  sufficient to impart to the projectile the desired velocity while simultaneously compressing the sabot to a point of fracture at which point it acquires brittle characteristics so that the dynamic forces acting upon it cause it to fracture, and fragment. The resulting sabot fragments become entrained in the gases of explosion leaving the barrel through the muzzle of the firearm. Experimental firing has indicated that all of the relatively light sabot material leaves the barrel through the muzzle. However, should any sabot material remaining in the spent cartridge it will be removed from the chamber with the extracted spent cartridges. Initial indications are that sabot residue will not be a problem.  
      Referring now to  FIG. 13  of the drawings another round of ammunition embodying the ammunition system of the present invention is shown. And is indicated generally by the reference numeral  50   a . The round  50   a  is similar, in most respect, to the round  50  previously described and parts of the round  50   a  which are substantially identical to parts of the previously describes round  50  bear the same reference numerals and a letter “a” suffix and will not be hereinafter further described. Like the round of ammunition  50 , the round  50   a  includes a cartridge case,  52   a  projectile  54   a  and a propellant charge  58   a . However, the sabot used in the round  50   a  has a circumaxally spaced apart series of axially forwardly extending pedal  88 , 88 . The number of pedals provided may vary, however, the illustrated sabot has four (4) such pedals defined by an equangularly spaced apart series of axially rearwardly extending slots  90 , 90 , substantially as shown. The forwardly facing surfaces of the pedals comprise surfaces which are disposed in generally abutting engagement with a reawardly facing annular abutment surface of the modified chamber  20 . The provision of pedals on an otherwise generally cylindrical sabot alter the projectile holding characteristics of the sabot to provide faster release of its associated projectile, where desired.  
      Yet another cartridge or round of ammunition embodying the present ammunition system is shown in  FIGS. 17-19  and indicated generally by the reference numeral  50   c . The illustrated round  50  differs from the previously described round  50   b  both in the construction and arrangement of its sabot and in the length of its cartridge case  52   c . Specifically, the sabot  56   c  has a plurality of circumaxially spaced apart axially forwardly extending petals  88   c ,  88   c , six shown. The petals extend for some distance beyond the mouth of the cartridge case. Each petal  88   c  has a generally forwardly facing bearing surface  92 . The bearing surfaces  92 ,  92  are defined by a rearwardly diverging conical surface of revolution centered on the central axis of the sabot. These surfaces are disposed in abutting engagement with complimentary surfaces on the transitional surface of the chamber of the firearm, as previously discussed. Since the overall length of the cartridge  52   c  is dictated by the axial length of an associated revolver cylinder  18   c . The case  52   c  is shortened to allow for the bearing surfaces on the sabot which project forwardly beyond the mouth of the cartridge at substantially as shown in  FIG. 17 .