Abstract:
A convertible sidearm is provided which can convert easily between a firearm and a knife. The convertible sidearm includes a tubular body frame. A back plate member assembly is removably affixed to the tubular body at one end. The back plate assembly includes a plate member and a substantially tubular support member emanating outwardly from a planar surface of the plate member. A standard bolt or bolt carrier assembly from a primary firearm, having a bolt and a firing pin connected thereto, is inserted into the tubular support member of the back plate member assembly. A spring-loaded striker is positioned proximal to a firing pin within the bolt carrier assembly. A trigger communicates with the spring-loaded striker to release the striker toward the firing pin to fire the weapon. The firearm is easily converted to a knife by removing the barrel of the firearm and replacing it with a blade assembly and removing the bolt carrier assembly from the back plate member assembly and re-installing the back plate member within the tubular body member. Alternatively, the convertible sidearm may employ a permanent firing mechanism instead of a removable bolt or bolt carrier.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a convertible sidearm. More specifically, the present invention relates to a sidearm which is easily convertible between a knife and a firearm. 
     In the small arms industry, there has been a serious ongoing concern with reliability of firearms and the reduction of the overall number of weapons to be carried, particularly by military personnel. Since the mid-1960s, the armies of the world have standardized on automatic rifles which fire small caliber, high-velocity ammunition. These gas-operated firearms are prone to malfunctions and jamming, particularly when they have not been cleaned for extended periods of time, a condition which can be expected during actual combat conditions when it is not uncommon for weapons to go days without cleaning. For example, a rifle such as the U.S. 5.56 mm M16-A2, which has not been cleaned, can malfunction when its gas tube system clogs with gunpowder residue, or when grit, sand, or gunpowder residue accumulates in the upper receiver or chamber areas so as to cause a stuck bolt or cartridge. Modern rifles can also be disabled when struck with shrapnel or flying debris. Further, during the heat of battle, or when crossing difficult terrain such as a swamp or river, a soldier&#39;s rifle can be easily dropped and lost. When a soldier&#39;s rifle is disabled or lost in a combat area, the soldier is left defenseless and highly vulnerable. 
     In modem warfare, the soldier&#39;s bayonet does not make up for the loss of his or her shoulder weapon, as rarely do combat distances permit hand-to-hand combat. The modem bayonet has essentially become a utility knife, used primarily for cutting lines, wire, kindling wood, etc. 
     In view of the foregoing, attempts have been made in the prior art to address these concerns. Known prior art multi-use weapons are actually combination-type weapons in that they simultaneously provide different functions. For example, known designs include combination knife and pistol configurations where a pistol firearm mechanism, with associated barrel, is incorporated into knife handle which is complete with knife blade fully attached. In addition, prior combination weapon designs include concealed pistols within a knife handle or concealed knives within a pistol body. Such configurations for concealed weapons within the body of another weapon typically include a firearm assembly which is chambered for low-powered pistol type ammunition. Further, sights for such combination pistol and knife weapons were typically not included. 
     Therefore, in view of the concerns discussed above, it would be desirable for a knife or bayonet to be convertible into a single-shot pistol-type defense weapon for a soldier with a lost or damaged shoulder-weapon, which fires the standard rifle ammunition which the soldier would be carrying. The current world army standardization on small caliber, high velocity service rifle ammunition makes it possible for such a weapon offering dual-use of rifle ammunition to be manufactured, due to the lower recoil of present rifle cartridges such as U.S. 5.56 mm NATO. It is also desirable that such a weapon could provide the useful knife-type features of a bayonet, and with only a marginal addition in cost and weight. It is further desirable that this weapon be capable of employing the bolt assembly of a soldier&#39;s service rifle, during conversion into a firearm, to reduce the cost and weight of the convertible sidearm. This would result in a highly effective weapon for a soldier&#39;s defense until he has been able to either remove himself from the combat situation, repair his shoulder-weapon, or obtain a replacement shoulder weapon. In particular, a convertible knife pistol would be highly desirable and also enable a rifleman to remain armed while searching or exploring confined areas such as tunnels, “spider-holes”, or enemy vehicles, in which a service rifle would be too large to employ effectively. A true convertible sidearm between a knife and a firearm would also be of great use as a survival weapon, or as part of a survival kit. Such a knife pistol would also permit a soldier, in a forward combat position, to remain defensively armed while cleaning his service rifle. 
     Still further, a convertible knife pistol would also provide benefits to police and security personnel, as well as outdoorsmen. Since there have been numerous incidents in which criminals have worn body armor, such as bullet-proof vests during the commission of a crime which cannot be pierced by the low-powered ammunition of a policeman&#39;s sidearm, the employment of a lightweight convertible weapon that can fire high-powered ammunition is highly desirable. Since the arming of every policeman with a high-powered rifle is neither practical nor cost-effective, a convertible knife pistol chambered for a high-velocity cartridge would enable law-enforcement officers to defeat criminals wearing such body armor. After the converted pistol has been fired, it may alternatively be used as a club or baton weapon also. In addition, campers and outdoorsmen often travel to desolate areas in which protection from large animals or potential wrong-doers is unavailable and to constantly carry a traditional firearm would prove impractical or cause unwanted attention. A weapon which is capable of converting between a knife and a high-powered firearm would prove advantageous to outdoorsmen as well. 
     SUMMARY OF THE INVENTION 
     The present invention preserves the advantages of prior sidearms. In addition, this sidearm provides new advantages not found in prior sidearms, and overcomes many of the disadvantages of such weapons. 
     The invention is generally directed to a novel and unique sidearm with particular application in situations requiring dual-use of a knife weapon that is convertible into a firearm capable of accommodating high-powered ammunition. The convertible sidearm of the present invention enables the quick and easy conversion between a knife weapon to a high-powered firearm while using many common parts to avoid excess components being carried by the user. 
     The preferred embodiment of the convertible weapon of the present invention includes a body frame of a substantially tubular configuration and which can be split into two halves to facilitate assembly, repair, and maintenance. A back plate member assembly is removably affixed to the tubular body frame at one end. The back plate assembly includes a plate member shaped like a knife pommel and a substantially tubular support member emanating outwardly from a surface of the plate member. A bolt carrier assembly, having a bolt and a firing pin connected thereto, resides within the tubular support member of the back plate member assembly. A spring-loaded striker is positioned proximal to the bolt and firing pin within the bolt carrier assembly. A trigger and sear engage with the spring-loaded striker to release the striker toward the firing pin to fire the weapon. The firearm is easily converted to a knife configuration by replacing the barrel of the firearm with a blade assembly and removing the bolt carrier assembly from the back plate member assembly and re-installing the back plate member within the tubular body member. 
     In operation, the invention easily converts between a firearm and a knife configuration. To assemble a knife, in accordance with the present invention, a blade assembly is first connected to the tubular body frame which also serves as the handle for the knife. The blade assembly is preferably retained in place by a locking collar. A back plate member is removably affixed to the tubular body at a first open end via a first connection such as by spring clips. In this condition, the construction is suitable for use as a knife weapon or knife tool. 
     To convert the weapon into a firearm, the blade assembly is first removed from the tubular body frame. A firearm barrel is affixed to the tubular body frame via a locking collar or other means at an opening in the tubular body frame. The back plate member assembly is removed from the opposite end of the tubular support member. A standard bolt or bolt carrier assembly, such as that of an M-16 rifle, is installed in the tubular support member of the back plate member assembly. A round of ammunition is then loaded into the chamber of the barrel via a cartridge port in the body frame. The combined bolt carrier and the back plate assembly are inserted into the tubular body frame to engage the sear with the striker of the bolt carrier assembly to effectively retract the striker in preparation for firing. The back plate is then secured to the tubular body frame by spring clips or the like. 
     A firearm trigger, which also serves as a knife guard when the construction is in a knife configuration, is depressed to disengage the sear from the striker to thereby cause the striker in the bolt carrier to urge the firing pin into the primer of the ammunition cartridge thus causing the ammunition to be fired. The spent cartridge body may then be ejected through the cartridge port to clear the chamber for additional rounds by withdrawing the bolt carrier and back plate assembly. 
     It is therefore an object of the present invention to provide a sidearm which may easily and quickly converted between a knife weapon or knife tool and a firearm. 
     An additional object of the present invention is to provide a convertible weapon that can provide a single shot pistol-type defense weapon. 
     Another object of the present invention is to provide a convertible weapon which provides a back-up weapon if a primary weapon fails. 
     It is another object of the present invention to provide a convertible weapon that utilizes parts or components of a primary weapon to reduce the overall weight that needs to be carried by a user and the overall cost of the weapon. 
     It is a further object of the present invention to provide a convertible weapon which provides a back-up firearm that can accommodate high-powered ammunition. 
     It is yet a further object of the present invention to provide a convertible sidearm with a knife blade for use as a weapon or useful tool. 
     It is another object of the present invention to provide a convertible weapon that accommodates high-powered ammunition in a small size. 
     It is a further object of the present invention to provide a convertible weapon that provides common use of components when in use as either a knife or a firearm. 
     It is an object to employ use of a knife scabbard as part of the convertible knife weapon system to reduce the possibility of loss of parts. 
     It is a further object of the present invention to provide a convertible weapon which makes use of a bolt assembly which locks directly to a barrel assembly to permit other components to be made of lightweight materials to reduce the weight of the weapon. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the present invention are set forth in the appended claims. However, the invention&#39;s preferred embodiments, together with further objects and attendant advantages, will be best understood by reference to the following detailed description taken in connection with the accompanying drawings in which: 
     FIG. 1 is a perspective view of the convertible weapon of the present invention in a knife configuration; 
     FIG. 2 is a front view of the convertible weapon shown in FIG. 1; 
     FIG. 3 is a top view of the convertible weapon shown in FIG. 1; 
     FIG. 4 is a bottom view of the convertible weapon shown in FIG. 1; 
     FIG. 5 is a left end view of the convertible weapon shown in FIG. 1; 
     FIG. 6 is a right end view of the convertible weapon shown in FIG. 1; 
     FIG. 7 is a front, partially cross-sectional view of the convertible weapon shown in FIG. 1 with blade portion partially installed; 
     FIG. 8 is a perspective view of the convertible weapon of the present invention of FIG. 1 being converted into a firearm; 
     FIG. 9 is a front view of the firing mechanism in accordance with the present invention; 
     FIG. 10 is a close-up front view of the sear and safety lock assembly in the convertible weapon of the present invention; 
     FIG. 11 is a cross-sectional view through the line  11 — 11  of FIG. 9; 
     FIG. 12 is the cross-sectional view of FIG. 11 illustrating spring-biased release of the side clips of the body frame in accordance with the present invention; 
     FIG. 13 is an exploded perspective view of the entire firing assembly in accordance with the present invention; 
     FIG. 14 is a perspective view of the bolt carrier and bolt carrier support assembly; 
     FIG. 15 is a cross-sectional view of the firing assembly of the present invention, with left body frame removed, illustrating initial installation of the bolt carrier and extension housing assembly into the handle of the weapon; 
     FIG. 16 is a cross-sectional view of the firing assembly of the present invention illustrating initial contact of the sear and the spring-loaded striker of the bolt carrier support assembly; 
     FIG. 17 is a cross-sectional view of the firing assembly of the present invention illustrating the spring-loaded striker of the bolt carrier in a cocked position; 
     FIG. 18 is a cross-sectional view of the firing assembly of the present invention illustrating firing of the weapon; 
     FIG. 19 is a side view of a knife scabbard with a firearm barrel incorporated in the knife scabbard in accordance with the present invention; 
     FIG. 20 is an alternative embodiment of the scabbard at FIG. 19 in accordance with the present invention; 
     FIG. 21 is an alternative embodiment of the present invention with a shotgun-style break-open action; and 
     FIG. 22 is another alternative embodiment of the present invention with a direct ammunition loading configuration. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The convertible sidearm of the present invention is a true convertible weapon in that it is assembled in either a firearm or a knife configuration. Unlike combination firearm and knife weapons, the convertible weapon of the present invention can only operate distinctly as a firearm or as a knife at a given time. Combination weapons, typically provide the capability to operate as a firearm and a knife simultaneously thus requiring fully operational components for both weapons at all times. As will be shown in detail below, the key critical differences between the convertible weapon of the present invention from prior known combination weapons is that the present invention includes an integral firearm mechanism which cannot operate as a handgun without removing the knife blade and replacing it with a barrel. Conversely, it cannot operate as a knife without replacing the firearm barrel with a blade assembly. In addition, the present invention provides a knife blade which is removed from the grip and a barrel is then attached which aligns and is co-axial with the contained firing mechanism. Further, due to the unique design of the convertible sidearm of the present invention, namely the employment of a locking bolt assembly, high-powered ammunition may be fired. Also, the convertible weapon of the present invention is not intended to be a concealed weapon as are most previous combination-type weapons. It also permits the capability for the firearm mechanism to utilize the bolt from another weapon, such as the U.S. M-16 rifle, when converted to fire ammunition. 
     Referring first to FIG. 1, a perspective view of the convertible sidearm  10  of the present invention is shown, particularly in its knife weapon or knife tool configuration. The invention consists of a firearm mechanism housed in a dual-purpose handle body which serves both as a knife handle and a firearm body or receiver. As will be described in detail below, the knife blade may be removed and a firearm barrel installed in place thereof to convert it into a firearm. 
     Now referring to FIGS. 1-6, the present invention  10  is shown in its general bayonet knife configuration which includes a dual-purpose body handle  12  and a blade member  14  connected thereto and held in place by a locking collar  42 . Further, in the knife configuration shown in FIGS. 1-6, member  16  is a bayonet ring for attachment to a rifle barrel and member  18  serves as a knife guard. However, as will be described in detail below, these members also have specific firearm functions. For example, member  16  also serves as a firearm sight and member  18  serves as a trigger when the convertible weapon of the present invention is used in a firearm configuration. FIGS. 2-6 show respective front, top, bottom, left end and right end views of the convertible sidearm  10  of the present invention when configured as a knife. As can be readily understood, the knife configuration of the present invention can be used as a knife weapon or tool depending on the needs of the user at the present time. Due to the size, construction and configuration of the knife assembly, it will function equally well to a bayonet or knife which is of a non-convertible nature. 
     Referring now to FIG. 7, details of the construction of the handle body  12  and interconnection of blade member  14  thereto is shown. In particular, blade member  14  is preferably provided with a knife base  38  and a flange  36  which is positioned about the circumference and behind the ricasso  39  of blade member  14 . Preferably, handle body  12  also includes a male threaded neck  40  with a central bore  104  therethrough. To effectuate interconnection of blade member  14  to body handle  12  to complete the blade or knife configuration of the present invention, knife base  38  is inserted into central bore  104 . Locking collar  42  is threaded onto male threaded neck  40  so that female threads  44  engage therewith and seat  45  engages flange  36  to effectively secure blade member  14  to handle body  12 . It should be understood, however, that the foregoing locking collar attachment method is a preferred construction but other connection configurations may be employed, independently or in unison with the locking collar method, such as direct threads on the knife blade member  14  or bolting by means of push-pull pin type quick release fasteners. FIG. 7 further illustrates the general internal assembly within handle body  12  and particularly how it is unused and undisturbed when the convertible sidearm  10  is configured as a knife. The internal firearm mechanism is only used when the convertible sidearm  10  of the present invention is configured as a firearm. 
     Referring now to FIGS. 8-18, the conversion of the convertible weapon  10  of the present invention into a firearm weapon, and the use thereof, is shown and described in detail. Referring first to FIG. 8, a perspective view of the convertible weapon  10  of the present invention is shown to include handle body  12 , which is the same handle body  12  shown in FIGS. 1-7, but is now to be used in the firearm configuration of the present invention. To convert the weapon from a knife assembly to a firearm, the blade member  14  is disconnected from the handle body  12  by disengaging locking collar  42  from male threaded neck  40  thereby permitting knife base  38  to be removed from bore  104 . FIG. 8 specifically illustrates the installation of a firearm barrel  46  in place of the blade member  14  of the knife configuration of the present invention. In similar fashion to the blade member  14 , firearm barrel  46  employs locking collar  52  with female threads  54  thereon for engaging with male threaded neck  40 . The firearm barrel  46  includes a base  56  which is installable within the bore  104  shown in FIG.  7 . In similar fashion to the blade member, barrel  46  is preferably secured in place via locking collar  52  and may employ other attachment methods as discussed above. In addition, firearm barrel  46  may optionally include a flip-up front sight  50  and flash suppressor  55 . In addition, channels  125  and abutments  129  in barrel  46 , are provided to receive and engage a bolt, as will be described below. 
     Referring now to FIGS. 9-13, the internal assembly of handle body  12  is shown. FIG. 13 illustrates an exploded perspective view of the internal assembly of handle body  12 . In particular, a substantially tubular body frame, generally referred as  20 , is provided with a left half frame  20   a  and a mating right half frame  20   b  which are secured together via fasteners  82 ,  108  and respective female threaded apertures  85  and  106  on right frame  20   b . Fasteners  82  and  108  pass through respective apertures  83  and  110  in left frame  20   a  to engage with female threaded apertures  85  and  106 . The right frame  20   b  carries trigger assembly  34 , sear assembly  62  and safety mechanism  76 . A cartridge insertion and ejection port  102  is provided within the side wall of right frame  20   b  which also receives a removable port cover  112 . A bayonet ring now acting as a rear firearm sight  16 , as earlier discussed, is provided at the upper edge of right frame  20   b  for sighting purposes during firing of the convertible weapon  10  of the present invention. 
     Referring now to FIG.  13  and in conjunction with FIGS. 9 and 10, trigger assembly  34  includes a fixed post  72  which resides at the end of slots located on the inner sides of frames  20   a  and  20   b , and which engages with trigger spring  74  by depression of trigger button  18 . Sear  62  is provided at fixed pivot  63  with a tip end  64  and cam surface  66 . The sear  62  is spring-biased with its tip  64  in an upward position by engagement of wire spring  68  with fixed post  70 . Rotating safety lock assembly  76  includes a rounded surface  78  and cut-out surfaces  80   a  and  80   b . When safety knob  76  is rotated with rounded surface  78  in an upward position adjacent to sear tip  64 , sear tip  64  will be immobilized thus preventing the firearm from firing. In this upward position, bolt carrier tubular member  26  is likewise locked in place as is trigger assembly  34 . As seen in sectional drawing FIG. 10, rotation of safety knob  78  approximately 180° from that in FIG. 9, which has left frame  20   a  removed for clarity, orients angled surface  80  adjacent to sear tip  64  to allow sear tip  64  to move downwardly and, thus, permitting firing of the sidearm. This position also orients cut-out surface  80   b  to unlock the safety from bolt carrier tubular member  26 . As can be understood, this safety knob configuration  76  is one of many safety configurations that may be employed in accordance with the present invention. 
     Referring now to FIGS. 9,  13  and  14 , the engagement of a bolt carrier assembly  116 , in this case from a U.S. M-16 rifle with bolt carrier support assembly  22 , is shown. Bolt carrier support assembly  22  includes a back plate  24  and a tubular member  26  connected thereto. The front slots  96  and rear slots  98  are provided on opposing lateral sides of tube  26 . A striker tube  59  is provided within tube  26  which houses a spring-loaded striker  58 . The rear half of bolt carrier  116 , as best seen in FIG. 14, resides within tube  26 . Key members  28 ,  130  are provided on the top of tube  26  as well as key member  128  on bolt carrier  116  for rotationally orienting bolt carrier  116  and bolt carrier support member within frame  20 . In addition, spring-biased lock tab  30  resides within carrier support tube slot  32  to engage with bolt carrier shoulder  122  upon full insertion of bolt carrier  116  within tube  26 . Once bolt carrier  116  is installed within bolt carrier support assembly  22 , bolt carrier  116  and bolt carrier support assembly  22  move as a single unit, with striker tube  59  now secured in place within the rear of bolt carrier  116 , as best seen in FIG.  14 . 
     The loading and cocking of the present invention when in a firearm configuration is shown in detail in FIGS. 15-18. In addition, FIGS. 11 and 12 illustrate the use of spring-biased locking clips  84  to retain the combined bolt carrier  116  and bolt carrier support assembly in place. More specifically, FIGS. 15-18 illustrate the steps of preparing and firing the convertible weapon  10  of the present invention. Referring first to FIG. 15, bolt carrier  116  and bolt carrier support assembly  22  are connected together as shown in FIG.  14 . The combined unit is then inserted into the substantially tubular cavity formed by half cavities  100   a  and  100   b  provided when frames  20   a  and  20   b  are mated and installed together. It is preferred that left frame  20   a  and right frame  20   b  remained assembled to form an entire substantially tubular frame at all times. Disassembly of frames  20   a  and  20   b  is only required for cleaning or maintenance of the weapon. 
     Still referring to FIG. 15, the combination structure of bolt carrier  116  and bolt carrier support assembly  22  is inserted into frame  20 . As seen in connection with FIG. 13, bolt carrier  116  also includes bolt  118  with locking lugs  124  and bolt face  140 . Firing pin  126  is also provided. Bolt cam pin  132 , which is moveable between a front and rear position, is also provided. Upon installing the combined bolt carrier  116  and support assembly  22 , bolt cam pin  132  is in a forward position with bolt extended. The further insertion of combined assemblies  116  and  22  engages a cartridge  144 , which has previously been inserted into the chamber of barrel  46 , locking bolt  118  to barrel  46  in preparation for firing. 
     FIG. 16 illustrates further installation of bolt carrier  116  and support assembly  22  so that sear tip  64  engages with spring-loaded striker  58  compressing coil spring  138 . Still further, installation of bolt carrier  116  and support assembly  22  causes striker  58  to be drawn back against the forces of coil spring  138  as seen in FIG.  17 . As a result, striker  58  is drawn away from firing pin  126  within bolt carrier  116 . The bolt carrier  116  is urged into frame  20  so that bolt  118  locking lugs  124  engage with barrel locking channels  142  of barrel  46  to securely lock bolt face  140  to the base of barrel  46  to seal the barrel chamber for firing. The circular locking motion of bolt  118  with locking lugs  124  is effected by bolt cam pin  132  which rides into a cam slot cut into the side of left half frame  20   a  to turn bolt  118  as bolt carrier  116  is moved forward. During the preparation for firing of the weapon, striker  58  is drawn back by the sear tip  64  riding through an elongated channel  61  in the bottom portion of tube  59 . In addition, an elongated channel  134  is provided in the bottom portion of tube  26  to permit sear tip  64  to travel within tube  26  to effectuate the compression of striker spring  138  with striker  58  within striker tube  59 . Essentially, channels  61  and  134  provide a pass through for striker  58  and sear tip  64  during the preparation for firing. 
     The firing of the weapon  10  of the present invention is carried out through the communication of striker  58  with firing pin  126  which, in turn, communicates with cartridge  144  to fire the weapon and launch the bullet. More specifically, trigger assembly  34  is employed by, as shown in FIG. 18, moving trigger button  18  rearwardly against the forces of trigger spring  74  and sear spring  68  to urge trigger cam surface  73  against sear cam surface  66  to, in turn, lower sear tip  64  off striker seat  60 . As a result, striker  58  will hit firing pin  126  for immediate firing of the weapon with the assistance of coil spring  138 . 
     The bolt carrier support assembly  22  may be secured in a front position and a rear position. As the combination assembly of bolt carrier  116  and bolt carrier support assembly  22  is inserted into frame  20 , spring-biased locking clips  84 , as best seen in FIGS.  11  and  12  are employed to maintain combined assemblies  116  and  22  in a desired front position for firing of the firearm. As seen in FIG. 13, front slots  96  and rear slots  98  are provided to engage with side tabs  92 . The locking clips  84  are secured to frame  20  via a fixed pivot pin  86  and are spring-biased into a closed position via coil spring  88 . It should be understood that for clarity purposes only, the right spring clip  84  is shown to simplify description thereof. It should be understood that an identical, mirror image left spring clip  84  is also provided. 
     When pinch tabs  90  are depressed, spring clips  84  are opened to lift intermediary tabs  92  and top tabs  94  from their respective resting positions. In particular, pinch tabs  90  are employed whenever it is necessary for intermediary tabs  92  and top tabs  94  are required to engage with another structure. For example, during the installation of the combination structure of bolt carrier  116  and support assembly  22 , spring clips  84  must be opened to permit the installation of bolt carrier  116  and support assembly  22  within frame  20 . Since, as described above, intermediary tabs  92  engage with either front slots  96  or rear slots  98 , once support assembly  22  is positioned so that intermediary tabs can engage with either front slots  96  or rear slots  98 , pinch tabs  90  can be released to secure support assembly  22  relative to frame  20 . Top tabs  94  are utilized to attach or remove sidearm  10  when in a bayonet configuration with blade attached, from a bayonet lug located beneath the barrel of a service rifle. When safety lock assembly  76  is moved to its upward locking position, it engages circular cut  27  in the base of bolt carrier support tube  26  as shown in FIG.  7 . Safety lock assembly  76  thereby secures assembly  22  in place when pinch tabs  90  are depressed and intermediary tabs  92  are lifted along with top tabs  94  when sidearm  10 , in a bayonet configuration, is being attached to a rifle. 
     The foregoing is particularly important during the preparation of the weapon for firing, as in FIG. 17, because spring clips  84  will engage with front slots  96  to maintain the spring forces of  138  to striker  58  on sear tip  64 . In the alternative, when the convertible sidearm  10  of the present invention is in a knife configuration, carrier assembly  22  is fully installed within frame  20  to provide a compact knife handle with secure end pommel. This can be accomplished because in this configuration no bolt carrier  116  is installed within support assembly  22 . As a result, support assembly  22  is secured to frame  20  via the engagement of spring clips  84  with rear slots  98  in tube  26 . 
     Referring now to FIG. 19, a scabbard  200  may be provided in accordance with the present invention. In particular, scabbard  200  includes an appendage  201  having a blade receptacle  204 . When not in use, as after sidearm  10  has been converted to a firearm configuration, blade member  14 , as shown in FIG. 1, may be detached from body  12  and housed within receptacle  204 . In addition, the scabbard  200  of FIG. 19 provides a firearm barrel  206  which is molded directly, or otherwise held, within scabbard  200 . Strap  202  holds sidearm  10  in scabbard  200  when configured as a knife or bayonet by being wrapped around handle  20  with ends of strap  202  secured together by snaps or buttons  205 . FIG.  19  and the scabbard  200  of the present invention clearly illustrate the use of the present invention as a convertible weapon where the weapon can only function as a knife or as a firearm. The barrel  206  is molded directly within pouch body  201  with a connection portion  203  of the firearm barrel being exposed to permit connection of the barrel to the handle body  12  even while scabbard appendage  201  remains connected thereto. This integrated barrel and scabbard configuration prevents loss of and provides easy access to the firearm barrel  206 . 
     FIG. 20 illustrates an alternative embodiment of the scabbard of FIG.  19 . Scabbard  300  includes a pouch body  301  with a blade receptacle  304  which functions as described in connection with FIG.  19 . In addition, a barrel pouch  306  is provided for receiving a separate firearm barrel  46  as seen in FIG. 8, for example. Firearm barrel  46  is housed within barrel pouch  306  and retained therein by a snap closure  308 . Strap  302  holds sidearm  10  in scabbard  300  when configured as a knife or bayonet by being wrapped around handle  20  with ends of strap  302  secured together by snaps or buttons  305 . 
     Turning now to FIGS. 21 and 22, alternate breech mechanism embodiments are shown of the convertible sidearm invention which do not require the addition of a bolt or bolt carrier assembly during conversion to a firearm configuration. In particular, FIG. 21 illustrates an alternative configuration  400  in which a break-open or tip-up style breech mechanism design is employed. Barrel  446  may be permanently connected to cartridge-receiving body  421  or connected via a locking collar as shown and described in connection with the preferred embodiment of the present invention. Trigger  418  is provided and functions in similar fashion as described above. Also, FIG. 22 illustrates yet a further alternative breech mechanism design  500  where no ejection or cartridge installation or removal port  102  is provided. In this embodiment, cartridge  544  is first installed within barrel  546  prior to connection of barrel  546  to body frame  520  via locking collar  552  and threaded neck  556 . Trigger  518  and sight  516  are provided in similar fashion to as described above. In embodiments  400  and  500  of FIGS. 21 and 22, the sidearm handle contains a complete firearm mechanism. To convert sidearm  10  from a knife or bayonet to a firearm only requires removal of the blade assembly and replacement with a barrel assembly without the need for adding an additional bolt assembly. Similarly, an alternative embodiment of sidearm  10  could consist of a design in which a bolt assembly is permanently contained within body handle  12 . 
     In particular, the convertible sidearm  10  of the present invention is unique in that it preferably employs a bolt carrier or bolt assembly which is withdrawn and used from another firearm such as a rifle. The ability to use a core component such as a bolt carrier within the convertible weapon of the present invention saves cost and valuable weight, particularly in a military application where weight of equipment is of particular concern. The present invention may accommodate a wide array of ammunition such as rifle, shotgun and pistol ammunition as well as tracer ammunition, flares, grenades, signal cartridges and noise cartridges. As seen in FIG. 1, bayonet catch  114  is provided to permit the easy mounting of the present invention, when in a knife configuration, to an existing rifle to act and serve as a bayonet. Likewise, sight  16  and the circular aperture therethrough, is utilized for forward mounting of sidearm  10  to a rifle for bayonet purposes 
     It will be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be covered by the appended claims.