Abstract:
Modular cartridges are disclosed that can be initially assembled, disassembled, and reprocessed by hand. The cartridge case is suitable for use with a variety of projectile designs and weights and for use with a range of propellant amounts and primer types. The variety of projectiles and range of propelling forces permits the present invention to provide cartridges for all types of uses, including indoor and outdoor target shooting, training, non-lethal self-protection, and lethal uses. The cartridges include a case, a projectile, a primer, and a selectable amount of propellant (if any), and primer housing insert” and which is configured to be releasably attached to the striking end of the case and to contain the primer and the desired amount of propellant.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to modular cartridge ammunition for rifle and handguns having reusable cases and projectiles and includes variations for practice, training, and self-defense. The present invention also relates to systems of such modular cartridge ammunition. 
         [0003]    2. Background of the Art 
         [0004]    Ammunition for rifles and handguns—collectively referred to herein as “small arms”—is modernly provided in the form of cartridges. Although cartridges come in many configurations and sizes, a typical center-fire cartridge  100  is show in cross-section in  FIG. 1 . 
         [0005]    The cartridge  100  includes a projectile  102  (which is commonly referred to as a “bullet”), an expansive case  104  (which is commonly referred to as a “casing” or a “shell”), propellant  106  (which is commonly referred to as “gun powder”), and a primer  108  (which is commonly referred to as a “cap” or “primer cap”). The projectile  102  is nested in a cavity at the discharge end  110  of the case  104  and held in place by circumferentially crimping the wall  112  of the case  104  against the projectile  102 . The primer  108  is press-fit into a primer-receiving cavity  114  at the striking end  116  of the case  104 . A small passageway called a flash-hole  118  extends through the end wall of the primer-receiving cavity  114  to provide communication between the primer-receiving cavity  114  and the propellant  106 . A flanged rim  120  extends circumferentially around the striking end  116  of the case  104  to help seat the cartridge  100  in the breech chamber of the small arm in which it is to be used. The exterior of the cartridge  100  is sized to fit into the small arm with which it is intended to be used and to provide predetermined levels of gas sealing during firing. 
         [0006]    To fire the cartridge  100 , it is first loaded into the breech chamber of the small arm and then locked into place. Pulling the trigger of the small arm causes a firing pin to strike against the striking end of the primer  108  to produce a concussion which causes the pressure-sensitive explosive which is contained within the primer  108  to explode. The hot gases and sparks produced by the explosion travel through the flash-hole  118  and ignite the propellant  106  which rapidly conflagrates to produce a high pressure gas pulse against the base  122  of the projectile  102  while causing the casing  104  to radially expand thus loosening its connection with the projectile  102 . Propelled by the high pressure gas pulse, the projectile  102  is accelerated to high speed as it travels through and out of the barrel of the small arm. The reactive force that corresponds to discharge of the projectile  102  pushes the small arm backwards toward the shooter. A portion of this reactive force is used in many small arms to operate a mechanism that removes the now empty case  104  from the small arm&#39;s breech and inserts another cartridge in its place ready for firing. 
         [0007]    Small arms ammunition cartridges are typically machine assembled. The primers and projectiles are typically designed for one-time use while the cases are often reconditioned and reused in machine-assembled cartridges or in user-reloaded cartridges assembled using hand-operated presses. 
         [0008]    For a given small arm, the amount of propellant and the design and type of the projectile are selected based upon the intended use of the shooter. For uses in which lethal force is desired, cartridges having heavy projectiles which are accelerated to high muzzle velocities by large amounts of propellants and high pressure primers are often chosen. For target practice and training uses, light, round-tip projectiles are typically used and the amount of propellant may be reduced or even eliminated altogether to lower the muzzle velocity of the projectile. In some training uses, even the projectile is eliminated. Thus, since each kind of shooting use is best satisfied by a cartridge having characteristics tailored to that use, a wide variety of cartridges are available for the typical small arm. However, it is costly to acquire and stock a variety of cartridges for a variety of uses. 
         [0009]    As is discussed in more detail in the Summary of the Invention and the Detailed Description of Preferred Embodiments sections below, the present invention makes small arm cartridge ammunition more affordable by providing modular cartridges that may be hand-assembled by the ultimate user. Although there have been many attempts in the past to satisfy this long-felt need of lower-cost user-assembled cartridge ammunition, none of the attempts have yielded all of the advantages which are produced by the present invention. In general, each of the previous attempts provided a single type of cartridge which was useful only for short-range target practice. In contrast, the present invention provides a wide variety of cartridges to satisfy a wide variety of uses. A few of the more notable previous attempts will now be discussed in the chronological order of their development. 
         [0010]    In 1880, U.S. Pat. No. 228,494 was issued to B. E. Valentine for a 0.50 caliber or larger rifle cartridge that was suited for training purpose and short ranges. The cartridge is described therein as a “compound cartridge” because it consisted of an outer case that was sized to fit the rifle breech chamber and an inner case that was inserted into the striking end of the outer case. The inner case was a smaller caliber blank cartridge. No propellant was used other than that which was contained in the blank cartridge. It was not necessary to fix the projectile into the cartridge and the projectile could even be loaded through the muzzle end of the rifle after the compound casing had been breech loaded into the rifle. If a space was left between the end of the inner case and the base of the projectile, sawdust or wads of pasteboard or felt could be placed therebetween. 
         [0011]    In 1904, Great Britain Patent No. 10,288 was issued to W. H. Trask for rifle cartridge that consisted of an outer case which was dimensioned to fit the rifle chamber. The outer case had a recess at its striking end for receiving an inner case in the form of a blank cartridge which was to be “inserted with the thumb and fingers, and pressed home as far as it would go.” No propellant was to be used other than that which was contained in the blank cartridge. A short lead projectile was to be inserted in the firing end of the outer case “with the fingers.” The cartridge was “best suited for the usual indoor range of 25 to 50 yards” but was said to provide “splendid shooting” at up to 100 yards or more. Nonetheless, it is clear from the small powder charge and the small projectile that this cartridge was suitable only for target practice. 
         [0012]    In 1933, U.S. Pat. No. 1,902,771 was issued to A. F. Gaidos for a “practice cartridge” which was described as being preferably used “in short range target practice or small game hunting.” Actually, Gaidos disclosed two different small arms cartridge designs (plus a third for use with a “small cannon”). The first cartridge design was similar to the cartridges of Valentine and Trask mentioned above, in that it used an outer case that fitted the gun&#39;s breech chamber and an inner case which comprised a blank that was fitted by hand into a recess of the outer case. This cartridge used no propellant other than that contained in the blank cartridge. The projectile could be seated by hand into the outer case using an alignment fixture. Gaidos&#39; second cartridge design was like the conventional cartridge 2 of FIG. 1 as described above in all respects except two. The first was that it had a two-piece case consisting of a first piece which was hollow and generally cylindrical and a second striking end closure piece that threaded onto the forward piece. The closure end piece had a recess which held a primer. This cartridge was assembled by introducing a projectile having a flared base into the rear open end of the forward piece of the case and sliding the projectile through forward piece until it seated against an internal shoulder of the forward piece. The hollow of the forward piece could then be loaded with a desired amount of propellant. Finally, the closure piece was screwed onto the end of the forward piece of the case. 
         [0013]    In 1959, U.S. Pat. No. 3,060,856 was issued to J. S. Dunn for a “practice round of ammunition.” Dunn&#39;s cartridge used only a primer as its source of projectile propelling force. Externally, the case of the cartridge was sized to fit the breech chamber in which it was to be used. Internally, the case had a first chamber for receiving the straight-walled narrow neck of a shouldered projectile, a second chamber for receiving a primer, and a narrow venturi beveled outwardly at both ends which was situated between the first and second chambers. The second chamber had on its striking end side a snap rim to hold the primer in place. No propellant was used. Both the case and the projectile were made of a moldable plastic. The projectile was to be somewhat softer than the case to facilitate the insertion and sealing of the projectile in the case. The projectile was said to be “reusable for about fifty shots without requiring extensive recovery operations or the use of special tools thereon.” The primer was to be inserted and removed with an awl or ice pick. 
         [0014]    In 1983, U.S. Pat. No. 4,391,199 was issued to L. Morin for “safe ammunition for exhibition and target shooting.” The ammunition comprised a plastic charge carrier, a holder, and a hollow plastic projectile. The charge carrier nested within the holder and had a central collar that engaged the holder&#39;s interior walls. Extending in opposite directions from the central collar was a nose end that had closed cone tip and a tail end which held a primer. The charge carrier also had a cylindrical chamber which extended between its tail and nose ends for holding a desired amount propellant. The charge carrier&#39;s nose nested within the hollow rear end of the projectile and connected the charge carrier to the projectile. During a shot, the charge carrier&#39;s nose split off along fracture line at the charge carrier&#39;s collar and was carried away with the projectile while the rest of the charge carrier remained in the gun with the base. The projectile was said to be reusable one time. 
         [0015]    In 1993, U.S. Pat. No. 5,259,319 was issued to R. Devecky et al. for “reusable training ammunition.” Although described to be used with 37 millimeter gas guns and 40 millimeter grenade launchers rather than small arms, mention is made here of this ammunition because of some features it shares with the hand-reloadable ammunition described above. Like the cartridges of Valentine and Trask, and the first cartridge design of Gaidos, the Devecky et al. cartridge used an outer case that fitted the breech chamber for which it was intended and an inner case which comprised a blank cartridge that was fitted by hand into a recess of the outer case and made use of no propellant other than that which was contained in the blank cartridge. Internally, the Devecky et al. outer case had four straight-walled interconnecting shouldered cylindrical chambers of decreasing radius which were interposed between its firing end and its blank-receiving recess. The projectile had hollow cylindrical chamber running from its tail end forward for about two-thirds of its length. The projectile had a three-step neck at its tail end. The first step was a short steep-angle bevel, the second step was a long shallow-angle bevel, and the third step was a short flat cylinder which stopped at the shoulder formed by the bottom of the forward section of the projectile. These steps permitted the neck to nest within the outer case&#39;s interconnecting chambers of decreasing radius without engaging their walls or the shoulders at their junctions. An o-ring was seated on the neck in a groove at the intersection of the second and third steps. This o-ring provided a seal and a resilient connection between the outer case and the projectile. Optionally, an o-ring groove could be provided in the inside wall of the outer case for receiving the o-ring when the projectile neck was properly nested with the outer case. Also, optionally, one or more o-rings could be seated in o-ring grooves on the forward portion of the projectile so as to act as “spin rings” which would engage rifling grooves of the gun&#39;s barrel as the projectile traveled down the barrel after being shot away from the case. The case and projectile were to be made of durable impact-resistant materials so as to be reusable. 
       SUMMARY OF THE INVENTION 
       [0016]    The present invention provides reusuable ammunition for rifles and handguns in the form of modular cartridges that can be initially assembled, disassembled, and reprocessed by hand in which the cartridge case is suitable for use with a variety of projectile designs and weights and for use with a range of propellant amounts and primer types. The variety of projectiles and range of propelling forces permits the present invention to provide cartridges for all types of uses, including indoor and outdoor target shooting, training, non-lethal self-protection, and lethal uses. 
         [0017]    The cartridges of the present invention are of a unique design which, in addition to a case, a projectile, a primer, and a selectable amount of propellant, comprise a novel component which is referred to herein as a “primer housing insert” and which is configured to be releasably attached to the striking end of the case. 
         [0018]    Externally, the primer housing insert has an elongated, generally cylindrical shape which is adapted proximal to its striking end to releasably connect to the cartridge case. Internally, the primer housing insert includes a primer cavity that is sized for receiving and retaining a selected primer. A communicating chamber (i.e., a passageway) extends from the primer cavity along the length of the primer housing insert to its discharge end. The geometry of the communicating chamber is selectively configured according the use the cartridge is to be put into which the primer housing insert is assembled. In some embodiments of the present invention, the primer housing insert may be of a one piece construction, while in others, it may comprise an outer section and an inner section. A one-piece construction is preferred in instances wherein the primer housing insert contains only a primer and a two-piece construction is preferred when a propellant is used in addition to the primer. 
         [0019]    The present invention also provides a variety of reusable-projectile designs for use as part of its cartridges. The design and materials of construction are selected based upon the intended use of the cartridge. 
         [0020]    The present invention also provides systems of modular cartridge ammunition. The systems comprise, for a given small arm, one or more cases into which can be fixed projectiles of different designs and a variety of primer housing inserts having a range of propelling force potential. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The criticality of the features and merits of the present invention will be better understood by reference to the attached drawings. It is to be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the present invention. Unless otherwise specified, the drawings are not to scale. 
           [0022]      FIG. 1  is a centerline longitudinal cross-sectional view of a typical prior art cartridge. 
           [0023]      FIGS. 2A-F  show a first pistol cartridge according to an embodiment of the present invention. 
           [0024]      FIG. 2A  is a side elevational view of the first pistol cartridge of  FIG. 2A . 
           [0025]      FIG. 2B  is a bottom view of the first pistol cartridge of  FIG. 2A . 
           [0026]      FIG. 2C  is an exploded perspective view of the first pistol cartridge of  FIG. 2A . 
           [0027]      FIG. 2D  is a centerline longitudinal view of the first pistol cartridge of  FIG. 2A . 
           [0028]      FIG. 2E  is a centerline longitudinal cross-sectional view of the first pistol cartridge of  FIG. 2A . 
           [0029]      FIG. 2F  is a partially cut-away perspective view of the first pistol cartridge of  FIG. 2A . 
           [0030]      FIG. 3  is a partially cross-sectional perspective view of a second pistol cartridge according to an embodiment of the present invention. 
           [0031]      FIG. 4  is an exploded longitudinal cross-sectional view of a first revolver cartridge according to an embodiment of the present invention. 
           [0032]      FIG. 5  is an exploded longitudinal cross-sectional view of a second revolver cartridge according to an embodiment of the present invention. 
           [0033]      FIG. 6  is an exploded bottom perspective view of a rifle cartridge according to an embodiment of the present invention. 
           [0034]      FIGS. 7A-7F  are longitudinal centerline cross-sectional views of examples of some of the many types projectile designs that may be used as part of the modular cartridges of the present invention. 
           [0035]      FIGS. 8A-8F  are as longitudinal centerline cross-sectional views of some of the configurations that the primer housing inserts of the present invention can have. 
           [0036]      FIG. 9  is a longitudinal centerline cross-sectional view of another pistol cartridge embodiment of the present invention showing an o-ring connection between the case and the primer housing insert. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0037]    In this section, some preferred embodiments of the present invention are described in detail sufficient for one skilled in the art to practice the present invention. It is to be understood, however, that the fact that a limited number of preferred embodiments are described herein does not in any way limit the scope of the present invention as set forth in the appended claims. It is also to be understood that whenever a range of values is presented, the range is to be construed as disclosing its endpoints and every point therebetween as if each point was expressly described. 
         [0038]    The present invention provides modular, hand-assembly cartridges for pistols, revolvers, and rifles. Several preferred embodiments are described in this section, with examples being given of pistol cartridges, revolver cartridges, and rifle cartridges. Additionally, for each particular type of pistol, revolver, and rifle, the present invention provides for a variety of different modular components which can be assembled to produce a cartridge that is tailored to the particular type of use the shooter desires, including indoor and outdoor target shooting, training, and self-protection uses. 
         [0039]      FIGS. 2A-F  show a first pistol cartridge  200  according to an embodiment of the present invention. The cartridge  200  is configured for use in indoor or outdoor target shooting and small game hunting. 
         [0040]      FIGS. 2A and 2B  are, respectively, a side elevational view and a bottom (striking end) view of the assembled cartridge  200 . In  FIG. 2A  the projectile  202  and the case  204  of the cartridge  200  are visible. In  FIG. 2B , portions of the case  204 , the primer housing insert  206 , and the primer  208  are visible.  FIG. 2C  is an exploded perspective view of the cartridge  200  which shows the three primary components of the cartridge  200 , i.e., the primer housing insert  206 , the case  204 , and the projectile  202 , prior to the components being hand-assembled by the user to construct the cartridge  200 . To make the assembly, the user simply manually nests and rotationally seats the primer housing insert  206  into the striking end  210  of the case  204  and manually seats the projectile  202  into the discharge end  212  of the case  204 . The exterior geometries of the case  204  and the projectile  202  are adapted to conform to the one or more breech chambers in which the cartridge the cartridge  200  is intended to be used. 
         [0041]    For an understanding of the interior configuration of the cartridge  200 , refer now to  FIG. 2D , which is a centerline longitudinal view of case  204  and to  FIGS. 2E and 2F , which are, respectively, a centerline longitudinal cross-sectional view and a partially cut-away perspective view of the cartridge  200 . The following discussion of the interior configuration of the cartridge  200  will start with a description of the case  204  and then progressively proceed to descriptions of the projectile  202  and the primer housing insert  206 . 
         [0042]    The case  204  has at its discharge end  212  a first cavity  214  (also called an “upper retaining pocket”) and a second cavity  216  (also called a “base pocket”) which are adapted to nestingly receive the intermediate and base (or neck) portions  218 ,  220  of the projectile  202 . Preferably, the shoulder  222  that is formed between the first and second cavities  214 ,  216  is beveled inward to help guide the projectile base  220  as it passes from the first to second cavities  214 ,  216  when the projectile  202  is being inserted into the case  204 . The walls  224 ,  226 , respectively, of the first and second cavities  214 ,  216  are preferably straight (as shown), but either or both of them may be partly or wholly tapered inward if desired to accommodate a similarly tapered projectile. A seating shoulder  228  is at the end of the second cavity  216  to accommodate the endface  230  of the projectile base  220 . 
         [0043]    Between the second cavity  216  and the striking end  210  of the case  204 , the interior of the case  204  has a passageway  232  (also called a “lower retaining pocket”) the sides of which are configured to accommodate the outer geometry of the primer housing insert  206 . These accommodations include threads  234  to engage the corresponding threads  236  of the primer housing insert  206  and a seating shoulder  238  against which a complimentary shoulder  240  of the primer housing insert  206  seats. 
         [0044]    The projectile  202  has a pressure chamber  242  extending along its longitudinal centerline from its base end. The pressure chamber  242  is dimensioned to nestingly receive the post  244  of the primer housing insert  206  so that the post  244  extends into the thick-walled intermediate portion  218  of the projectile  202 . The pressure chamber  242  is thus positioned to receive and dimensioned to accommodate the hot gas pressure pulse that is provided by the pressure housing insert  206  during firing. The dimensions of pressure chamber  242  also are chosen to promote the balanced and stable flight of the projectile  204 . The endwall  246  of the pressure chamber  242  may be of any configuration, e.g. flat, conical, etc., but is preferably domed so as to evenly distribute the pressure pulse to the projectile  202 . The corner  248  of the pressure chamber  242  where the pressure chamber  242  terminates at the endface  230  of the base  220  may be squared, but is preferably rounded or beveled so as to help guide the primer housing insert post  244  as it is introduced into the pressure chamber  242 . 
         [0045]    The projectile  202  is releasably held seated within the first and second chambers  214 ,  216  of the case  204  by the elastic force exerted by one or more slightly raised circumferential bands (which are referred to herein as “pressure bands”, e.g. pressure band  250 ) against at least one of the interior walls  224 ,  226  of the first and second chambers  214 ,  216 , respectively. 
         [0046]    The primer housing insert  206  has a primer  252  releasably retained within a primer-receiving cavity  254 . A passageway  256  extends axially from the primer-receiving cavity  254  to the discharge end  258  of the primer housing insert  206 . The walls  260  of the passageway  256  may be straight or may be tapered inwardly along all or a portion of the length of the passageway  256 . Optionally, the geometry of the walls  260  of the passageway  256  may take on other configurations so long as the walls  260  are designed to safely contain the hot gas pressure pulse that the passageway  256  is exposed to during the firing of the cartridge  200 . 
         [0047]    With the exception of the primer  208 , all of the components of the cartridge  200  may be constructed of a synthetic material, e.g., injectable plastic. Alternatively, the case, the projectile, and/or the primer housing insert may be constructed in whole or in part of a metal, e.g., brass, aluminum, or copper, to name a few. 
         [0048]    A second pistol cartridge  300  according to an embodiment of the present invention that is suitable for use self protection is shown in a partially cross-sectional perspective view in  FIG. 3 . Like the first pistol cartridge  200 , the second pistol cartridge  300  comprises three main components, namely a projectile  302 , a casing  304 , and a primer housing insert  306 . Also like the first pistol cartridge  200 , all of the components of the second pistol cartridge  300  are resusable—except of course for the spent primer and propellant (if any). However, the second cartridge  300  differs from the first cartridge  200  in three main respects. 
         [0049]    First, whereas the projectile  202  is a single piece component, the projectile  302  comprises a metal core  308  and a synthetic outer sleeve  310 . The metal core  308  provides for additional weight, impact force, and penetration. 
         [0050]    Second, in place of the pressure band  250  of projectile  202 , the projectile  302  has an o-ring  312  seated in an o-ring groove  314  on the outer surface of its inner core  312  for holding and sealing the projectile  302  in place in the case  304 . 
         [0051]    Third, the configuration of primer housing insert  306  is more complex than that of the primer housing insert  206 . The primer housing insert  306  includes an outer shell that is similar exteriorly to the primer housing insert  206  as it has threads  316  and a post  318  and is preferably made of a synthetic material. However, the inner configuration of the primer housing insert  306  is different in that it contains a metal liner  320 . The metal liner  320  has an outer flange  322  that forms the striking end endface of the primer housing insert  306 . The metal liner  320  also has a primer  324 , which is removably retained within a primer-receiving cavity  326 , and a passageway  328  extending from the primer-receiving cavity  326  to the discharge end of the primer housing insert  306 . Although the passageway  328  is adapted to optionally contain loose or pelletized propellant, e.g., such as propellant pellet  330  (which for clarity sake is shown in  FIG. 3  as floating in the passageway  328 ), in some embodiments the passageway  328  contains no propellant. In embodiments in which the passageway  328  does contain a propellant, it is necessary to provide a closure to the discharge end of the passageway  328  which will be dislodged or which will open upon firing so that the hot gas pressure pulse emanating from the primer and/or the propellant can exit the discharge end of the passageway  328 . The closure may be made by way of a plug or other dislodgable or burstable (e.g., a membrane of film) obstruction or, as shown in  FIG. 3 , by crimped closure  332  of the end of the metal liner  320 . 
         [0052]    Referring now to  FIG. 4 , there is shown an exploded longitudinal cross-sectional view of a first revolver cartridge  400  which has a single-piece synthetic projectile  402 , a case  404 , and a primer housing insert  406 . These components are similar to those shown with regard to first pistol cartridge  200 . The projectile  402  has a pressure band  408  that aids in sealingly retaining the base  410  of the projectile  402  in the base pocket  412  of the case  404 . The case  404  is similar to the base  204  with its features being adapted to the contours and dimensions of the different breech chamber for which it is designed to be used. The synthetic primer housing insert  406  removeably retains a primer  414  in a primer-receiving pocket  416  and has threads  418 , a post  420 , and a tapered-to-straight passageway  422  which are similar to the corresponding features of primer housing insert  206 . However, while the primer housing insert  202  contained only the primer  252 , the primer housing insert  406  contains, in addition to the primer  414 , a propellant pellet  424  (which for clarity sake are shown in  FIG. 4  as floating in the passageway  422 ), and a retaining plug  426 . 
         [0053]    In  FIG. 5 , a second revolver cartridge  500  according to an embodiment of the present invention is shown as an exploded longitudinal cross-sectional view. The cartridge  500  comprises a two-piece projectile  502 , a case  504 , and a primer housing insert  506 . The projectile  502  has a metal core  508  and a synthetic sleeve  510 . An elongated o-ring  512  is seated in a groove on the base  514  of the projectile  502  for sealingly retaining the projectile  502  within the case  504 . A small vent hole is provided in the base  514  to help relieve internal air pressure during the assembly of cartridge  500 . The case  504  is identical to the case  404 . The primer housing insert  506  is metal and has a crimped discharge end  516  to retain loose or pelletized propellant, e.g. propellant pellets  518  (which for clarity sake are shown in  FIG. 5  as floating in the passageway  520 ), and a primer  522  releasably retained within a primer-receiving cavity  524 . 
         [0054]    A rifle cartridge  600  according to an embodiment of the present invention is shown in  FIG. 6 , which is an exploded bottom perspective view showing all of the individual components and subcomponents of the cartridge  600 . The main components of the cartridge  600  are a projectile  602 , a case  604 , and a primer housing insert  606 . The subcomponents of the projectile  602  are a sleeve  608 , a metal core  610 , and an extended o-ring  612 . An o-ring groove  614  is provided in the metal core  610  for receiving the o-ring  612 . A small vent hole  616  is also provided in the metal core  610 . The metal primer housing insert  606  has threads  618  which are adapted to screw into complementary threads  620  of the case  604 . The discharge end  622  of the primer housing insert  606  is crimped closed. The primer housing insert  606  has as its subcomponents a propellant  624  and a primer  626 . Note that the flange  628  on the striking end of the primer house insert  606  has two recesses  630   a,    630   b  that allow for a rod, screwdriver tip, or a spanner tool to be used to help seat and unseat the primer housing insert  606  within case  604 . Note that the post  632  of the primer housing insert  606  has optional marking bands  634 . The color and number of marking bands  634  are used to readily indicate to the user the amount of propellant (if any) and/or the type of primer  626  that primer housing insert  606  contains. 
         [0055]    Referring to  FIGS. 7A-7F , there are shown longitudinal centerline cross-sectional views of examples of some of the many projectile designs that may be used as part of the modular cartridges of the present invention.  FIG. 7A  shows a synthetic practice service projectile  700 .  FIG. 7B  shows a training projectile  702  which has a rubber cap  704 , a synthetic body sleeve  706 , and a metal core  708  which has two groove-seated o-rings  710   a ,  710   b.    FIG. 7C  shows a training projectile  712  which has a synthetic body sleeve  714  and a metal core  716  which has a single o-ring  718 .  FIG. 7D  shows a self-defense projectile  720  which has a synthetic body sleeve  722  and an exposed round-tipped metal core  724  having a single groove-seated o-ring  726 .  FIG. 7E  shows another self-defense projectile  728 , this one having a synthetic body sleeve  730 , an exposed flat sinter tip metal core  732 , and a single groove-seated o-ring  734 . Finally,  FIG. 7F  shows still another self-defense projectile  736  which has a synthetic sleeve  738 , an exposed pointed stinger metal core  740 , and a single groove-seated o-ring  742 . 
         [0056]    Some of the configurations that the primer housing inserts of the present invention can have are illustrated in  FIGS. 8A-8F  as longitudinal centerline cross-sectional views. Note that in these figures when propellant is shown, for clarity it is depicted in the form of a floating stylized pellet. Propellant can be in the form of loose powder or as one or more pellets or as a combination of loose powder and pellets.  FIG. 8A  shows a synthetic body primer housing insert  800  having the configuration already described above for the primer housing insert  206 . It includes threads  802 , a post  804 , a primer  806 , and a tapered-to-straight passageway  808 .  FIG. 8B  shows a metal body primer housing insert  810  which has a propellant pellet  812  in its passageway  814  and a plug  816  closing the discharge end of the passageway  814 .  FIG. 8C  shows a two-piece primer housing insert  818  which has a synthetic outer body  820  and a metal liner  822 . The primer housing insert  818  is the same as the two-piece primer housing insert  306 , except that instead of having a crimped end to its passageway  824 , the passageway  824  is sealed with a plug  826 .  FIG. 8D  shows a two-piece primer housing insert  828  which is the same as the two-piece primer housing insert  306 .  FIG. 8E  shows another a two-piece primer housing insert  830  which differs from the two-piece primer housing inserts  818 ,  828  in three principal respects. First, the post  832  of its outer body  834  has a thinner wall than those of the other two primer housing inserts  818 ,  828 . Second, its passageway  836  is wider than those of the other two primer housing inserts  818 ,  828  allowing it to contain more propellant  838 . Third, instead of using crimping or a plug to close the discharge end of its passageway  836 , the primer housing insert  830  uses a thin film  840  for that purpose.  FIG. 8F  shows another two-piece primer housing insert  842 . Primer housing insert  842  is the same as the primer housing insert  830 , except that the discharge end of its passageway  844  has a crimped closure  846 . 
         [0057]    It is to be understood that although some features are described above as part of the description of one or another embodiment of the present invention, the present invention includes adapting the features shown on one embodiment for use on other embodiments. For example, some embodiments described using one or more o-rings to interconnect a projectile to a case while others described using one or more pressure bands for that purpose. The present invention contemplates embodiments which use one or the other or both of those means for interconnecting the projectile and case. 
         [0058]    It is also to be understood that it is preferred that all of the components of the modular cartridges of the present invention be made of materials which are environmentally friendly. Nonetheless, the inventor understands that environmentally friendly materials may not be available or affordable under some circumstances and so includes within the scope of the present invention the use of any and all types of materials which are fit on an engineering basis for use in the modular cartridges having the components described herein. 
         [0059]    It is also to be understood that any size and kind of primer and propellant that is otherwise suitable for use in a particular small arm may be used in the construction and use of the modular cartridges of the present invention. Also, although only center-fire cartridges are described above, rim-fire cartridges are also within the scope of the present invention and may be constructed by adapting the primer-receiving cavity and the passageway to be sufficiently off-center, at least at the striking end of the cartridge, for the firing pin of the small arm to fire the rimfire primer. Of course, if a particular small arm is adapted for use with both centerfire and rimfire cartridges, then either a centered location or an off-centered location for the rimfire primer may be used. 
         [0060]    Cases for use with modular cartridges of the present invention are preferably made from a synthetic material or a metal that is suitable for the pressures and handling that the cartridges are expected to encounter as well as providing a suitable atmospheric seal for avoiding any undesirable degradation of any propellant that the cartridge is to contain. 
         [0061]    At the time of the writing of this document, there are well over 500 different kinds of small firearm cartridges, most adapted to fit only the breech chamber of one particular small firearm. The present invention includes modular cartridges adapted for use in all existing small firearms as well as those small firearms that may be later developed. The modular cartridge system allows any particular firearm, the mixing and matching of primer housing inserts and projectiles with the cases adapted for use of that particular firearm, thus greatly simplifying stocking of ammunition. Accordingly, it is to be understood that the present invention includes within its scope systems and methods of operating the systems which include the provision and/or assembly and/or the disassembly of the components of the modular cartridges described herein. 
         [0062]    A preferred method of using the modular cartridge system of the present invention is to provide a shooter with the case, the projectile or projectiles of his choice, and the primer housing inserts having the loading and design of his choice, and permitting the shooter to assemble the cartridge himself or herself. It is also within the scope of the present invention that the modular cartridges be provided already assembled to the shooter. In either circumstance, after firing the cartridge, the shooter may recover the projectile for reuse (except in embodiments wherein a single-use projectile was used or a reusuable projectile becomes lost) and remove the primer housing insert from the case and replace it with a fresh primer housing insert and insert into the case along with the original or a different projectile. 
         [0063]    A primer housing insert may be reused by dislodging the spent primer from the primer-receiving cavity of the primer housing insert and replacing it with a fresh primer. If the primer housing insert was designed to hold propellant, the propellant may be replaced with the desired amount of fresh propellant which is safe for use in the particular primer housing insert and a suitable closure be made for the discharge end of the primer housing insert passageway. For safety reasons, it is preferred that the fired primer housing inserts be retuned to a manufacturer for reconditioning, particularly those which include a propellant and even more particularly, those which used a crimped closure to contain the propellant. 
         [0064]    It should be understood that although the modular cartridges of the present invention described above used a threaded connection for connecting the primer housing insert and the case, other means connections may be used. For example, a bayonet-type connector may be used, e.g., with the primer housing insert having one or more radially-extending projections which fit into complementary grooves of the case so that the primer housing may be seated by a combined rotating-thrust motion. Another connection means is the use of one or more releasable tab and slot combinations. A tab and slot combination optionally may also include the use of grooves for guiding the advance or withdrawal of the tab or tabs into or from the slot or slots. It is also to be understood that where threads are used as the connection means or as part of the connection means, the threads may be of the single-lead or of the multiple-lead type. An example of still another means of connection is shown in  FIG. 9  which is a longitudinal centerline cross section of a third pistol cartridge  900  according to an embodiment of the present invention. The cartridge  900  comprises a projectile  902 , a case  904 , and a primer housing insert  906 . The case  902  and the primer housing insert  906  are connected by way of o-rings  908   a,    908   b  which are seated in complentary o-ring grooves in the case  904  and the primer housing insert  906 . 
         [0065]    It is also be understood although the primer housing inserts described above contain a discrete primer, it is within the present invention to seat within the primer housing inserts cartridge blanks which contain a primer. In such embodiments, the primer-receiving cavity and the passageway may be combined in whole or in part to accommodate the blank. Such blanks may also include a desired amount propellant. 
         [0066]    It is to be understood that although the present invention is preferred for use with small arms, it is within the scope of the present invention that its modular cartridges described above be dimensionally configured for use with cartridges for larger weapons as well. Such cartridges would comprise a casing, a projectile, and a primer housing insert. 
         [0067]    It is also to be understood that since the present invention is primarily concerned with providing reusable components, the projectiles are preferably designed for non-lethal uses. However, it is within the scope of the present invention for the modular cartridges to include single-use projectiles that are designed for lethal uses, e.g., those that are designed to expand upon impact. To be sure, it is to be understood that the present invention encompasses the adaptation of all types of projectiles—both recoverable and non-recoverable (including those of lethal design)—for use with the modular cartridges described above. 
         [0068]    All patent applications and patents, both foreign and domestic, and all other publications referenced herein are incorporated herein in their entireties to the full extent permitted by law.