Patent Abstract:
A lock for a gun barrel has plugs insertable into the chamber and muzzle. The plugs impinge against existing stops on the barrel so as to limit travel of the plugs toward each other in the barrel. Once the plugs are in the barrel, a linkage connects them so that each stop prevents removal of the opposite plug from the barrel. Preferably the stops, such as the chamber diameter reduction and the muzzle choke seat, are inside the barrel and the length of each plug is coordinated with the distance to its in-barrel stop so that no part of the gun barrel lock is exposed to out-of-bore tampering. A lock prevents unauthorized disengagement of the linkage from the plugs. The gun barrel lock is of adjustable length and the plugs may have interchangeable diameter adapters to accommodate a variety of gun barrel lengths and calibers.

Full Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to accessories for firearms and more particularly concerns locks for plugging gun barrels. 
     The use of a lockable plug as a deterrent to unauthorized use or inadvertent or accidental discharge of a gun is well known. Such plugs typically rely on some form of inside-of-the-barrel plug expansion or outside-of-the-barrel plug compression to secure the plug in the barrel. 
     Plugs which radially expand within the barrel typically rely on frictional engagement against the circumferential wall of the barrel to resist removal of the plug from the barrel. They require complex expanding mechanisms in order to achieve sufficient frictional contact between the barrel and plug surfaces and, while the plug is in the barrel, a substantial portion of their operating structure is usually exposed to tampering outside of the barrel. While they are difficult for the user to install and remove, they offer only modest resistance to unauthorized removal of the plug from the barrel. Since, by definition, their expanding components must exert significant force against the barrel wall, they may all too easily mar or more severely damage the barrel surface in normal use. Because of the complexity of the expanding mechanisms, they generally can be used only with the specific caliber of weapon or length of barrel for which they are designed. In order to provide a more secure locking engagement than is possible with friction type expansion plugs, one variation of the expanding plug approach relies on radial expansion of locking pins. The plug is inserted through a narrow diameter portion of the barrel and the pins then extend into a wider diameter annular groove in the barrel. This grooving is, however, an unacceptable compromise of the barrel wall. 
     Plugs which operate by radial compression are generally inversions of the expanding plugs above described. They generally combine an in-the-barrel plug with an outside-the-barrel mechanism to secure the plug in place. The plug does not expand against the inner wall of the barrel. It only blocks the passage. It is held in place by an external structure. Some external structures frictionally grip the outer surface of the barrel. Others engage against a protrusion from the barrel to prevent removal. By reason of their compressive forces they, like the expansion plugs, are likely to mar or more severely damage the barrel, though at least only on the outside wall. However, these devices expose most, if not all, of the locking mechanism to outside-of-the-barrel tampering. 
     It is, therefore, an object of this invention to provide a gun barrel lock which deters unauthorized use and accidental or inadvertent discharge of a gun. Another object of this invention is to provide a gun barrel lock which is easily installed and removed by an authorized user. A further object of this invention is to provide a gun barrel lock which is substantially contained within the barrel. Yet another object of this invention is to provide a gun barrel lock which has most of its structure shielded from exposure to outside-the-barrel tampering. It is also an object of this invention to provide a gun barrel lock which does not exert radial forces against the inside wall of the barrel. Still another object of this invention is to provide a gun barrel lock which can be adjusted to accommodate barrels of different caliber. An additional object of this invention is to provide a gun barrel lock which can be adjusted to accommodate barrels of different length. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention a lock is provided for a gun barrel. A first plug is insertable into the chamber end of the gun barrel. A second plug is insertable into a muzzle end of the gun barrel. The plugs are adapted to impinge against portions of the barrel in their path during insertion so as to limit travel of the plugs toward each other in the barrel. A linkage is fixed at one end to one of the plugs and extends to and is adapted at the other end for engagement with the other plug so that the impingement of each plug against its associated barrel portion prevents removal of the other plug from the barrel. A lock prevents unauthorized disengagement of the adapted end of the linkage from its associated plug. Preferably, the linkage is of adjustable length to accommodate a variety of gun barrels. 
     In a preferred embodiment, cooperative means are provided on the in-bore ends of each plug for mating the plugs for simultaneous rotation about a longitudinal axis. The linkage is journalled at one end on one of the plugs for extension into the other plug. Cooperative means are also provided on the linkage and the other plug for coupling the plugs against longitudinal separation so that impingement of each plug prevents removal of the other plug from the barrel. The lock secures the linkage against rotation in its plug so as to prevent unauthorized disengagement of the linkage. 
     For a barrel end of constant diameter, such as the muzzle end of a hand gun or rifle, it is preferred that its associated plug have a flange for impingement against the corresponding outer end of the barrel. For gun barrels having a chamber with a chamfer at its outer end and a diameter reduction at its in-barrel end, it is preferred that its chamber plug have a stop for impingement against the chamfer or reduction inside the barrel. For gun barrels having a choke seat in the muzzle, it is preferred that its muzzle plug have a stop for impingement against the choke seat. Most preferably, the length of each plug will be coordinated with the distance from its end of the barrel to its in-barrel stop so as to stop travel of the plug into the barrel only after the plug is disposed entirely within the bore. In this configuration, no part of the gun barrel lock is exposed to out-of-bore tampering. 
     In order to adapt the gun barrel lock to a variety of gun calibers, the chamber plug may be made in two parts, a casing with a pocket and a housing with a post. The post is slidable in the pocket and a setscrew may be used to fix the post at any position in the pocket. Casings with different outer diameters for use with different caliber barrels all have identical pockets. The casings are readily interchangeable on the housing to convert a plug to a particular gun caliber. Similarly, the muzzle plug may be made in two parts, a body and a ring thereabout. Rings with a different outer diameter for use with different caliber barrels all have identical inside diameters. The rings are readily interchangeable on the body to convert a plug to a particular gun caliber. 
     In another embodiment of the gun barrel lock, the lock cylinder is mounted for rotation in the chamber plug with the locking member seat located in its in-bore end. The muzzle plug has a shaft extending to a locking member fixed at its in-bore end. The locking member is longitudinally insertable into and engagable for rotation with the locking member seat for coupling the plugs against longitudinal separation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a diametric cross-sectional view of a typical shotgun barrel; 
         FIG. 2  is a vertical plane diametric cross-sectional view of the assembled gun barrel lock; 
         FIG. 3  is a vertical plane diametric cross-sectional view of the plug assembly of the gun barrel lock of  FIG. 2 ; 
         FIG. 4  is a vertical plane diametric cross-sectional view of the lock assembly of the gun barrel lock of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view taken along the line  5 - 5  of  FIG. 2 ; 
         FIG. 6  is a cross-sectional view taken along the line  6 - 6  of  FIG. 2 ; 
         FIG. 7  is a cross-sectional view taken along the line  7 - 7  of  FIG. 2 ; 
         FIG. 8  is a cross-sectional view taken along the line  8 - 8  of  FIG. 2 ; 
         FIG. 9  is a cross-sectional view taken along the line  9 - 9  of  FIG. 2 ; 
         FIG. 10  is a cross-sectional view taken along the line  10 - 10  of  FIG. 2 ; 
         FIG. 11  is a cross-sectional view taken along the line  11 - 11  of  FIG. 2 ; 
         FIG. 12  is a cross-sectional view taken along the line  12 - 12  of  FIG. 2 ; 
         FIG. 13  is a cross-sectional view taken along the line  13 - 13  of  FIG. 2 ; 
         FIG. 14  is a cross-sectional view taken along the line  14 - 14  of  FIG. 2 ; 
         FIG. 15  is a cross-sectional view taken along the line  15 - 15  of  FIG. 2 ; 
         FIG. 16  is a vertical plane diametric cross-sectional view of the gun barrel lock of  FIG. 2  mounted in the gun barrel of  FIG. 1 ; 
         FIG. 17  is a vertical plane diametric cross-sectional view of an alternative chamber plug; 
         FIG. 18  is a vertical plane diametric cross-sectional view of another alternative chamber plug; 
         FIG. 19  is a vertical plane diametric cross-sectional view of an alternative muzzle plug; 
         FIG. 20  is a vertical plane diametric cross-sectional view of an integral plug embodiment of the gun barrel lock; 
         FIG. 21  is a vertical plane diametric cross-sectional view of an assembled gun barrel lock with a chamber plug lock cylinder; 
         FIG. 22  is a cross-sectional view taken along the line  22 - 22  of  FIG. 21 ; 
         FIG. 23  is a cross-sectional view taken along the line  23 - 23  of  FIG. 21 ; and 
         FIG. 24  is a cross-sectional view taken along the line  24 - 24  of  FIG. 21 . 
     
    
    
     While the invention will be described in connection with preferred embodiments thereof, it will be understood that it is not intended to limit the invention to those embodiments or to the details of the construction or arrangement of parts illustrated in the accompanying drawings. 
     DETAILED DESCRIPTION 
     The gun barrel lock herein described may be used with hand guns, rifles or shotguns. It is described in relation to use with a shotgun barrel  21 . The barrel  21 , illustrated in  FIG. 1 , has a bore  22  extending between its chamber  23  and muzzle  24 . A sight  25  is fixed atop the muzzle  24 . The in-bore end of the chamber  23  is tapered to form a chamber reduction  26  as is necessary for receiving a shotgun shell. The outer end of the chamber  23  has a chamfer  27  for the rim of the shell casing. In modern shotguns, the muzzle  24  may be widened to form a choke seat  28 . Older shotgun barrels do not have a choke seat  28 . The chamber reduction  26 , chamfer  27  and choke seat  28  are significant to the present disclosure because they can be used as stops to impinge against components of various embodiments of the gun barrel lock  31 . 
     Turning to  FIGS. 2-4 , an embodiment of the gun barrel lock  31  is illustrated which is particularly suited for use with the shotgun barrel  21  shown in  FIG. 1 . The gun barrel lock  31  consists essentially of a chamber plug  32 , a muzzle plug  33  and a linkage  34 . The linkage  34  interconnects the plugs  32  and  33  and has a lock  35  to reduce the likelihood of unauthorized disconnection. 
     Looking at  FIGS. 1-3 , the diameter of the chamber plug  32  is such that the plug  32  is insertable into the chamber  23  of the barrel  21 . The chamber plug  32  has a conical surface  36  which reduces the plug diameter so that the in-bore end of the plug  32  can pass through the chamber reduction  26  until the conical surface  36  impinges against the chamber reduction  26 . The impingement of the conical surface  36  against the chamber  26  prevents further travel of the chamber plug  32  into the barrel  21 . The diameter of the muzzle plug  33  is such that the plug  33  is inserted into the muzzle  24  of the barrel  21 . The in-bore portion of the muzzle plug  33  has a peripheral land  37  which impinges against the choke seat  28  as the muzzle plug  33  is inserted into the muzzle  24 . The impingement of the peripheral land  37  against the muzzle stop  28  prevents further travel of the muzzle plug  33  into the barrel  21 . Thus, when the linkage  34  interconnects the chamber plug  32  and the muzzle plug  33 , each plug  32  or  33  opposes the removal of the other plug  33  or  32  from the barrel  21 . 
     Looking at  FIGS. 2 ,  3  and  5 - 9 , the chamber plug  32  has a casing  41  which is preferably similar in its outer configuration to the casing of a shotgun shell that would be loaded into the chamber  23 . The casing  41  has a pocket  42  which receives a post  43  extending from a locking member housing  44 . The post  43  slides longitudinally in the pocket  42  and a set screw  45  is used to secure and release the casing  41  to and from the housing  44 . Thus, the set screw  45  can be used to adjust the length of the chamber plug  32  or to allow casings  41  and housings  44  to be interchanged. The chamber plug  32  has a seat  46  of non-circular cross-section accessible from the internal end of the plug  32 . As shown in  FIG. 9 , the seat cross-section is rectangular. 
     Looking at  FIGS. 2 ,  3  and  9 - 16 , the muzzle plug  33  has a body  51  with an annular flange  52  of outer diameter less than the inner diameter of the muzzle  24 . A ring  53  slides over the body  51  against the flange  52 . The diameter of the ring  53  is greater than the diameter of the bore  22  of the barrel  21  at the muzzle stop  28  but less than the diameter of the muzzle  24 . In this embodiment, the in-bore face of the ring  53  is the peripheral surface  34  which will impinge against the muzzle stop  28 . The body  51  of the muzzle plug  33  has a sleeve  54  extending from the in-bore end of the body  51  into the barrel  21 . The inside diameter of the sleeve  54  is coordinated to slide on the outside diameter of a circular tube  55  so as to telescope the length of the muzzle plug  33 . The circular tube  55  has a block  56  welded to its free end. The block  56  is shaped to be seated in and complement the seat  46 . As best seen in  FIG. 9 , the block  56 , like the seat  46 , is rectangular. Since the seat  46  and the block  56  are non-circular, when the block  56  is in the seat  46 , rotation of the circular tube  55  will cause in-unison rotation of the housing  44 . The casing  41 , which is secured to the post  43  by the set screw  45 , will also rotate in unison with the circular tube  55 . By telescoping the circular tube  55  in the sleeve  54 , the distance between the conical surface  36  of the chamber plug  32  and the peripheral land  37  of the muzzle plug  33  can be adjusted to conform to the distance between the chamber and muzzle stops  26  and  28  in the gun barrel  21 . A set screw  57  is used to secure the sleeve  54  to the circular tube  55  and set the chamber plug  32  and muzzle plug  33  at the desired spacing. Since the set screw  57  also secures the circular tube  55  against rotation in the sleeve  54 , the plugs  32  and  33  will rotate in unison when the block  56  is in its seat  46 . Thus, the plugs  32  and  33 , as shown in  FIG. 3 , will all rotate together. However, without the linkage  34 , the block  56  can be freely withdrawn from the seat  46  to longitudinally separate the plugs  32  and  33  from each other. 
     Turning now to  FIGS. 2 ,  4  and  6 - 15 , the linkage  34  has a round shaft  71  tapered at its tip to provide a shaft guide  72 . A locking member  73  is fixed to the shaft  71 . Preferably, the locking member  73  is a pin which extends diametrically through the shaft  71 . The other end of the shaft  71  is welded to a square tube  74  which slides on a square rod  75  to telescope the linkage  34 . A lock cylinder  76  operable by a key  77  is fixed, possibly by a weld, to the end of the square rod  75 . An annular channel  78  is provided on the surface of the shaft  71 . Operation of the key  77  turns the linkage  34  and its locking member  73 . The lock cylinder has a lock ring  79  threaded on its in-bore end. 
     As seen in  FIG. 2 , the body  51  of the muzzle plug  33  provides a housing  58  for the lock cylinder  76 . The locking member housing  44  of the chamber plug  32  is hollow and forms a bearing  47  for the shaft guide  72 , a circular chamber  48  to rotationally receive the locking member  73  and a diametric slot  49  to slidably pass the locking member  73  into the chamber  48 . The block  56  has a longitudinal opening  59  aligned with the opening through the circular tube  55  so that the shaft  71  can extend through and rotate in the block  56  with the square tube  74  rotating in the circular tube  55 . The block  56  also has a radial opening  61  extending into the longitudinal opening  59 . A pin  62  is threaded into the radial opening  61 . With the shaft  71  inserted into the longitudinal opening  59  in the block  56  until the opening  59  aligns with the annular channel  78  in the shaft  71 , the pin  62  is screwed into the block  56  until it penetrates into but does not contact the channel  78 . Thus, the linkage  34  is free to rotate in the block  56  of the muzzle plug  33  but cannot be longitudinally withdrawn from the block  56 . 
     To install the gun barrel lock  31  in the shotgun barrel  21 , the stop-to-stop distance from approximately the center of the chamber reduction  26  to the choke seat  28  is measured. The shaft guide  72  is inserted through the seat  46  into the bearing  47  until the locking member  73  has passed through the slot  49  into the chamber  48  and the block  56  is fully seated in the seat  46 . The round tube  55  is inserted into the sleeve  54  and telescoped so that the distance from approximately the center of the conical surface  36  on the chamber plug  32  to the peripheral land  37  on the muzzle plug  33  is approximately the same as the measured stop-to-stop distance inside the barrel  21 . The set screw  57  is tightened to secure the circular tube  55  in this position in the sleeve  54 . The shaft  71  is then withdrawn from the locking member housing  44 . The separated chamber and muzzle plugs  32  and  33  can now be inserted into the chamber  23  and muzzle  24  until the conical surface  36  and peripheral land  37  contact their respective stops  26  and  28 . In this position, the block  56  should be fully seated in the seat  46  and the locking member  73  aligned in the circular chamber  48  of the locking member housing  44 . Turning the key  77  should rotate the linkage  34  approximately ninety degrees to shift the locking member  73  out of alignment with the diametric slot  49  so that the linkage  34  cannot be disengaged from the chamber plug  32 . 
     It is preferred that the length of the chamber and muzzle plugs  32  and  33  be such that, when installed in the barrel  21  as above described and as shown in  FIG. 16 , the entire barrel lock  31 , including both plugs  32  and  33 , is within the barrel  21  and no component of the barrel lock  31  is accessible outside of the barrel. Since the barrel lock  31  is free to rotate inside the barrel  21  and cannot be withdrawn from either end of the barrel  21 , it is extremely difficult to tamper with the barrel lock  31  without damaging the surface of the barrel  21 . 
     Another chamber plug  81  is illustrated in  FIG. 17 . The lock member housing  82  has a diameter  83  which will pass through the chamber reduction  26  of the barrel  21 . The casing  84  has a flange or rim  85  which will impinge against the chamfer  27  on the chamber  23 . The chamfer  27  serves as the chamber stop and the length of the barrel lock  31  is measured accordingly. The barrel lock  31  is still entirely within the barrel  21 . One advantage of this type of chamber plug  81  is that casings  84  of different diameters  86  can have identical pockets  87  so that the same housing  82  can be used for a variety of casings  84  to accommodate different caliber guns. The user need only loosen the set screw  88 , remove the post  89  of one housing, replace the casing  84  with one suited to the appropriate caliber and tighten its set screw  88 . 
     Similar interchangeability can be achieved with the type of chamber plug  91  illustrated in  FIG. 18 . The lock member housing  92  has a diameter  93  which will pass through the chamber reduction  26  of the barrel  21 . A stop ring  94  is engaged on threads  95  on the lock member housing  92  so that its longitudinal position on the housing  92  can be adjusted. The diameter  96  of the stop ring  94  is such that it will impinge against the chamber reduction  26 . The casings  97  can be interchanged on the housing posts  98  using the set screw  99  in the same manner as above described. 
     Turning to  FIG. 19 , another type of muzzle plug  101  is illustrated which is intended for use with rifles, hand guns and, as shown, shotguns which do not have a choke seat  28  in the muzzle  24 . The muzzle plug  101  has a body  102 , sleeve  103  and set screw  104  with a lock cylinder housing  105  in the body  102 , substantially as in the muzzle plug  33  of  FIG. 2 . However, the lock cylinder end of the body  102  has an annular flange  106  with a diameter  107  greater than the diameter  108  of the muzzle  24 . Thus, when the sleeve  103  and body  102  are inserted into the muzzle  24 , the annular flange  106  will impinge against the outer end of the muzzle  24  to prevent further insertion of the muzzle plug  101  into the barrel  21 . To reduce the possibility of outside-the-bore tampering with the muzzle plug  111 , the outer surface  109  of the flange  106  is arcuate so as to resist gripping of or cutting into the flange  106 . 
     An integral type of muzzle plug  121  is illustrated in  FIG. 20 . The muzzle plug  121  has a body  122 , a sleeve  123  with a set screw  124  and a lock cylinder housing  125  substantially the same as the muzzle plug  33  illustrated in  FIG. 3 . However, the integral muzzle plug  121  does not employ a ring  53  which is interchangeable for different caliber weapons. Rather, the body  122  of the plug  121  extends to a peripheral land  126  which will impinge against the muzzle stop  28  when the muzzle plug  121  is inserted in the muzzle  24 . For different caliber guns, it will be necessary, therefore, to replace the entire body  122  and sleeve  123  of the integral muzzle plug  121 . Also shown is an integral type of chamber plug  131 . This chamber plug  131  is similar to the plug  32  shown in  FIG. 3  except the casing portion  132  and housing portion  133  are an integral unit. Similarly, the chamber plugs  32 ,  81  and  91  of  FIGS. 3 ,  17  and  18  may also be integrally formed. 
     Looking at  FIGS. 21-24 , a gun barrel lock  151  is illustrated which has a lock cylinder  152  in its chamber plug  153 . The chamber plug  153  has a conical surface  154  which will engage against the chamber reduction  26  of the barrel  21  shown in  FIG. 1 . However, in this embodiment, the lock member housing  155  extends from and rotates with the lock cylinder  152  so that the housing  155  turns with the key  156 . The lock member housing  155  provides a bearing  157 , a circular chamber  158  and a slot  159  similar to the muzzle lock cylinder embodiments hereinbefore described. The housing  155  can be threaded  160  to the casing end of the plug  153  to permit mounting of the lock cylinder  152 . In this chamber lock cylinder embodiment, the shaft  161  on which the locking member  162  is engaged is welded or otherwise fixed at its muzzle end to a square rod  163  which is connected or welded at its other end to a circular member or tube  164 . When the locking member  162  is aligned in the chamber  158  in the lock member housing  155 , the square rod  163  is fully inserted into a seat  165  so that the chamber plug  153 , the locking member  162 , the square rod  163  and square tube  164  rotate in unison but independently of the lock member housing  155  and key  156 . When the key  156  is turned, the lock member housing  155  turns and the locking member  162  engages in the circular chamber  158  to prevent separation of the chamber plug  153  from the muzzle plug  171 . In this embodiment, the muzzle plug  171  as shown has a body  172  with a flange  173  for engaging on the end of the muzzle  24 , as was illustrated and described in greater detail in relation to  FIG. 19 . The flanged plug  171  is internally threaded to engage an external thread  174  on the muzzle end of the circular member  164 . Any of the embodiments of the muzzle plugs illustrated in  FIGS. 16 ,  19  and  20  could also be used. Similarly, features of other embodiments of the chamber plugs, such as the threaded embodiment of  FIG. 18 , can be incorporated into the lock cylinder chamber plug  153 . The length of the gun barrel lock  151  can be changed, for example by rotating the muzzle plug  171  on the threads  174  as shown or by telescoping the rod  163  or member  164  as hereinbefore discussed with respect to other embodiments of the gun barrel lock. 
     The invention has been described in relation to use with a shotgun barrel. However, the barrel lock is useful with handguns and rifles as well. While it has been described in relation to the lock cylinder being on the muzzle end and the lock member being on the chamber end, this relationship can be reversed or, as illustrated in  FIGS. 21-24 , combined in one plug. Different types of chamber and muzzle plugs can be interchanged to suit the gun to which the lock is applied. If a given barrel lock is always used with the same gun, it is not necessary to change the length of the plugs or linkage once they have been set. On the other hand, if the user wishes to switch the same barrel lock from one gun to another, the set screw adjustments readily permit changing the length of the gun lock to accommodate the length of the barrel. Furthermore, one or both of the plugs can be exchanged to accommodate specific calibers of weapons and, most preferably, muzzle rings can be changed and chamber plugs adjusted to more easily accommodate the change in caliber. All threaded engagements are preferably sealed to prevent unauthorized disengagement of the threads. 
     Thus, it is apparent that there has been provided, in accordance with the invention, a motor vehicle radiator shield that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.

Technology Classification (CPC): 5