Patent Publication Number: US-7908782-B1

Title: Pivot mount for firearm sighting devices

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to firearms and more particularly to firearm sighting devices. Even more specifically the present invention concerns a pivot mount by which a particular firearm sighting device, such as an optical or laser sighting device is releasably mounted to the sight mounting rail of a tactical firearm by a locking lever operated clamp mechanism and, when so mounted, a sight support portion of the mount is pivotally moveable between an operative position at which the sighting device is useable for the purpose of sighting on a target and an inoperative position at which the sighting device is positioned out of the normal line of sight of the firearm. The present invention also concerns a pivot mount for a firearm sighting device or other firearm related implement that is adapted for manual unlocking and pivotal movement, without necessitating the use of any tools or other equipment. 
     2. Description of the Prior Art 
     Virtually all firearms are provided with mechanical sighting devices, many of which are selectively adjustable by the user to accomplish bullet strike as nearly as possible to a point of aim. Firearms, particularly rifles, have for a considerable period of time been provided with mechanical sights, typically referred to as “iron sights”, and with additional sighting devices, such as telescopes and other optical sighting devices. At times, if the mechanical sighting device cannot be readily used with an optical sighting device in place, it is desirable to remove the optical sighting device from the firearm. Typically, removal of an optical sighting device from a firearm requires the use of certain tools and equipment and the risk of losing sight mounting or adjusting parts if such an activity is carried out in a field environment. Moreover, removal of a sighting device from a firearm inevitably results in the loss of zero, thus requiring the firearm to be again sighted in after the sighting device has been re-installed on the firearm. For these reasons, telescope sighting devices and sight mounts have been developed to permit hinged or pivotal movement of a telescope from an operative sighting position to a laterally off-set inoperative position. These improvements enable a telescope to be swung to and from a sighting position on a firearm without requiring re-adjustment of the sight. U.S. Pat. Nos. 2,639,507 and 2,644,237 of Pachmayr and 2,803,880 of Weaver are representative of pivotally mounted telescopes of this nature. 
     More recently, especially in the tactical firearm environment various firearm sighting devices are often mounted on firearms in tandem so that the cumulative benefit of dual sighting devices enhances the character of firearm use. For example, an optical sighting device and a thermal or night vision sighting device can be used in tandem to provide the user with the capability for using optical sighting during conditions of poor light. Laser sighting devices are used in conjunction with telescope sights to provide the user with the benefits of a magnified image of a target and with laser sighting of the target. At times it is beneficial to eliminate a sighting device from the line of sight, but to do so ordinarily requires the use of tools or other equipment. In the tactical environment, military or law enforcement personnel do not ordinarily have sufficient available time for sight removal or installation, so the need for changes of sighting devices has largely remained unsatisfied. 
     Even more recently tactical personnel have been provided with the capability for efficient release and removal of an optical sighting device from a firearm having a mounting rail and re-installing the sighting device precisely to its previous zero condition. U.S. Pat. No. 7,272,904 of Mark C. LaRue concerns an adjustable locking lever operated Picatinny rail clamp mechanism providing this sight removal and replacement capability while maintaining a previously established zero. 
     There is a current need, especially in the field of tactical firearms, to provide a mounting device for optical sighting devices and other sight related devices that have a pivotal capability for movement of sighting devices between operative and inoperative positions without requiring the use of tools or equipment of any nature. Especially in the tactical environment is desirable to provide a pivotal optical sight mount that secures an optical sight device against inadvertent movement even when the sighting device has been moved to its inoperative position. It is also desirable to provide a pivot mount that can be easily and quickly removed from a firearm together with its optical sighting device, transported to a site for use, and then re-installed on the firearm in sight zero condition, so that the firearm can be used immediately for precision firing. 
     SUMMARY OF THE INVENTION 
     It is a principal feature of the present invention to provide a novel pivot mount mechanism for optical sighting devices and other sight related implements that permits the user of a firearm to manually release the pivot mount from its operative position and rotate the pivot mount to an inoperative sight position without any requirement for the use of tools or other equipment. 
     It is another feature of the present invention to provide a novel pivotal firearm sight mount mechanism that stabilizes a sight mount and its sighting device at both the operative and inoperative positions of the sighting device to prevent any inadvertent movement or noise of the sighting device as the firearm is handled. 
     It is also a feature of the present invention to provide a novel pivotal firearm sight mount mechanism that is incorporated with a lever actuated sight rail clamping mechanism, thus permitting the entire pivot mount mechanism to be removed from a firearm and replaced without losing the previously sighted zero of the sighting mechanism. 
     It is an even further feature of the present invention to provide a novel pivotal firearm sight mount mechanism that is selectively moveable between operative and inoperative positions relative to a firearm without any requirement for the use of tools or special equipment to permit such movement. 
     Briefly, the various objects and features of the present invention are realized by providing a pivot mount base that is assembled to or removed from the sight mounting rail of a firearm by a lever actuated cam energized rail clamping mechanism. The pivot mount base is provided with spaced upstanding bosses that provide for rotational and linear movement of a pivot shaft that is located within shaft passages of the bosses. A pivot shaft locator pin extending transversely through the pivot shaft is adapted to be received in selective position controlling relation by pairs of aligned shaft location receptacles defined by one of the bosses or by other structure of the mount base. A sight support device is fixed to and rotates along with the pivot shaft and serves to retain a firearm sighting device, such as a telescope, for example. The sight support device and sighting device are pivotally moveable about the center-line of the pivot shaft between an operative position where the sighting device can be used to sight the firearm on a target and an inoperative position where the sighting device is positioned laterally offset from its operative position. The sight support device, in addition to being mounted in fixed relation with the pivot shaft, is spring energized along with the pivot shaft to secure the sighting device in forcible contact with position controlling surfaces of the mount and thus secure the sighting device against inadvertent movement and noise at both its operative and inoperative positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the preferred embodiment thereof which is illustrated in the appended drawings, which drawings are incorporated as a part hereof. 
       It is to be noted however, that the appended drawings illustrate only a typical embodiment of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
       In the Drawings: 
         FIG. 1  is an elevational view showing the receiver part of a tactical firearm and showing two sighting devices mounted to the Picatinny rail of the firearm, with one of the sight mounting mechanisms being a pivot mount embodying the principles of the present invention; 
         FIG. 2  is an isometric illustration of the pivot mount mechanism of  FIG. 1 , showing the operative position of the sight support device thereof; 
         FIG. 3  is another isometric illustration of the pivot mount mechanism of  FIGS. 1 and 2 , showing the operative position of the sight support device thereof from another point of view; 
         FIG. 4  is an isometric illustration of the pivot mount mechanism of  FIGS. 1-3 , showing the inoperative, i.e., laterally offset position of the sight support device thereof; 
         FIG. 5  is a plan view of the pivot mount mechanism of  FIGS. 1-4 , showing the laterally offset inoperative position of the sight support device; 
         FIG. 6  is an end view of the pivot mount mechanism of  FIG. 4 , showing the laterally offset inoperative position of the sight support device; 
         FIG. 7  is an isometric illustration of the pivot mount mechanism of  FIGS. 5 and 6 , also showing the inoperative, i.e., laterally offset position of the sight support device; 
         FIG. 8  is a partial sectional view taken along line  8 - 8  of  FIG. 5  and showing the detailed construction of the lever actuated mounting base locking mechanism; 
         FIG. 9  is a plan view of the pivot mount mechanism of  FIGS. 1-4 , showing the laterally offset but intermediate position of the sight support device as occurs during pivotal movement of the sight support device between its operative and inoperative positions; 
         FIG. 10  is an end view of the pivot mount mechanism of  FIG. 9 , showing the intermediate position of the sight support device; and 
         FIG. 11  is a sectional view taken along line  11 - 11  of  FIG. 10  and showing the pivot mount base and its sight support positioning control mechanism in detail. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring now to the drawings and first to the elevational view of  FIG. 1 , there is shown a portion of a tactical firearm generally at  10  having a Picatinny or other sight mounting rail  11  fixed to or integral with the receiver  12  of the firearm. The sight mounting rail  11  defines upwardly facing angulated clamping support surfaces and downwardly facing angulated clamping surfaces as will be explained in detail below. A pair of sighting devices  16  and  18  are positioned in tandem or series on the firearm, being supported and positioned by sight support members  20  and  22  that are in turn supported and positioned on the firearm by lever actuated sight mount rail clamp mechanisms  24  and  26 . The lever actuated sight mount rail clamp mechanism shown generally at  26  in  FIG. 2  has a mounting base structure  28  that is constructed essentially according to the teachings of U.S. Pat. No. 7,272,904 of LaRue, which patent is incorporated herein by reference for all purposes. A base location key  29  projects downwardly from the under side of the mounting base  28  and extends into a selected key slot of the Picatinny or other sight mounting rail for selected location of the mounting base and its sighting device with respect to the rail. It should be borne in mind that the sight mounting base structure  28  may be of a form that is mounted directly to the receiver of a firearm if it is not desired to provide for removal and replacement of sighting devices without loss of sighting zero. Non-tactical permanently mounted sighting devices of this nature can be efficiently used in the recreational shooting environment to permit selective movement of a telescope or other sighting device between operative and inoperative positions to facilitate use of the iron sights of the firearm. 
     The mounting base  28  is configured to define a rail receiving receptacle  30  with spaced, downwardly and oppositely angulated surfaces  32  and  34  which are oriented for contact with correspondingly angulated upwardly facing support surfaces  33  and  35  of the rail  11 . The mounting base  28  also defines an upwardly facing angulated surface  36  that is positioned for retaining engagement with a correspondingly angulated clamping surface  37  of the rail  11 . A locking platform  38  is integral with and extends laterally from the mounting base  28  and defines an opening  40  within which is seated an annular insert  42  as shown in  FIG. 8 . The annular insert is composed of a suitable hard, wear and impact resistant metal material such as steel, stainless steel, titanium alloy or any suitable non-metal material having wear and impact resistance. The annular insert  42  defines a central opening  41  that receives an upwardly projecting circular shoulder  43  of a spline/spindle shaft or post  44  in rotatable relation therein. 
     The spline/spindle shaft  44  is integral with and projects upwardly from a manually rotated cam plate  46  of a locking lever structure  48  as shown in  FIGS. 5 ,  7  and  8 . The manually rotated locking lever structure  48  of each sight mount assembly  24  and  26  is manipulated, i.e., rotated, for locking and unlocking of the sight mounting bases  24  and  26  from the sight mounting rail  11  when it is desired to remove and replace either of the optical sighting devices  20  and  22 . Especially when the sighting device is being used on firearms during tactical activities, this feature permits the sighting devices and the mounts thereof to be removed from a firearm and carried in protective fashion, such as in a pocket of a personnel pack, and when its use is needed the user will simply and quickly clamp the sighting device to the rail device  11  of the firearm, with the sighting device being accurately positioned at its pre-set sighting position or zero. This feature permits a sighting device to be unlocked, removed and re-assembled and locked in place without losing its preset aim point or zero. 
     The spline/spindle shaft  44  defines a shaft section  50  of non-circular cross-sectional configuration that is received within a corresponding non-circular opening  52  of a circular drive member  54 , thus establishing a linearly moveable but non-rotatable relation of the circular drive member with respect to the spline/spindle shaft  44 . A compression spring member  56  is located within a circular spring receptacle or pocket  58  and establishes spring force transmitting relation with the circular drive member. The compression spring maintains the circular drive member  54  in force transmitting relation with an adjustment nut member  60  that is threaded to an outer threaded section  62  of the spline/spindle shaft  44 . This feature accomplishes synchronous rotation of the shaft  44 , circular drive member  54  and adjustment nut  60  and, since there is no relative rotation of components, overcomes any tendency for loosening or tightening of the adjustment nut when the shaft  44  is rotated by the locking lever  48 . The adjustment nut is rotatably adjusted with a simple hex wrench by the user of the firearm to achieve desired clamping force of the lever actuated clamp mechanism. Such adjustment ensures that the sight mount and thus the sighting device is retained to the Picatinny rail with optimum force causing the sighting device to assume its previous zero with precision when assembled and locked at its previous location on the Picatinny rail. 
     As mentioned above, it is desirable at times to eliminate one of the sighting devices, such as the sighting device  18 , from the line of sight of the user of the firearm. It has been found practical to establish pivotal mounting for a sighting device so that it can be pivoted from an operative position for sighting on a target to an inoperative position, out of the line of sight of the user, so that another mechanical or optical sighting device can be used exclusively for firearm sighting. It is also desirable, when a sighting device has been pivotally moved to an inoperative position, to ensure that the sighting device and its mounting mechanism do not move inadvertently as the firearm is moved and does not make noise when the firearm is handled. This feature is especially important in the use of firearms during tactical operations where inadvertent movement of any component of a firearm or any noise resulting from such movement can result in a disadvantage to the user or other personnel in association with the user. 
     As shown in the sectional view of  FIG. 11  and also in  FIGS. 2 and 4 , a pair of spaced upstanding pivot bosses  64  and  66  project upwardly from the mounting base  28  and are machined to define transverse bores  68  and  70  through which extend end portions  72  and  74  of a rotatable pivot shaft  76 . Conversely, an upwardly projection portion of a mounting base can be machined to define a slot, with a pivot shaft rotatably mounted to portions of the mounting base and extending across the slot. The pivot bosses  64  and  66  define opposed inner end surfaces  65  and  67  that define a space or slot  69  therebetween. The boss  66  defines an enlarged passage section forming an annular spring chamber  78  within which a portion of a compression spring  80  is located. The compression spring bears against a circular internal shoulder  82  within the boss  66  and also bears against an annular shoulder  84  of the pivot shaft  76  and may also bear against an axial end portion of a sight support member. Thus, the pivot shaft is urged in one linear direction, toward the boss  64  by the force of the compression spring  80 . The space or slot  69  is sufficiently wide to permit manually energized axial movement of the sight support member as will be explained in detail below. 
     As is evident from  FIGS. 2 ,  5 ,  7 ,  9  and  11 , the pivot boss  64  is machined to define a first pair of pivot shaft location receptacles  86  and  88  which are generally horizontally aligned and intersect the center-line  90  of the rotatable pivot shaft  76 . The location and orientation of the first pair of pivot shaft location receptacles establish the operative or sighting position of the sighting device  18 . The pivot boss  64  is also machined to define a second pair of generally vertically aligned pivot shaft location receptacles  87  and  89  that are preferably oriented in substantially 90° angular relation with respect to the first pair of pivot shaft location receptacles  86  and  88 . It should be borne in mind, however, that the second pair of generally vertically aligned pivot shaft location receptacles  87  and  89  establish a laterally offset inoperative position of the sighting device  18  and thus need not be precisely located in 90° angular relation with the first pair of pivot shaft location receptacles. It is only important that the sighting device be moved to a selected lateral position with respect to the line of firearm sighting where it will be located as desired by the firearm user for efficient and effective use of the remaining sighting device. 
     It is desirable to provide a suitable means for establishing at least one operational rotational position of the pivot shaft for selective positioning of the sighting device  18  at an operative position for precision sighting of the firearm on a target. This feature can be accomplished by establishing pivot shaft location surfaces on the pivot mount, which surfaces are engaged by one or more corresponding shaft rotation location surfaces or members that are integral with or fixed to the pivot shaft. According to the preferred embodiment of the present invention, a pivot shaft locator pin  92  is fixed within a transverse bore of the pivot shaft  76  and has end portions  91  and  93  projecting beyond the cylindrical outer surface  94  of the end portion  72  of the pivot shaft  76 . The pivot shaft locator pin  92  is preferably of cylindrical configuration and is composed of hardened wear resistant material such as steel. The end portions  91  and  93  of the pin are positioned for selective engagement within substantially 90° offset first and second pairs of the pivot shaft location receptacles of the upstanding boss  64  of the mount base  28 . Each of the pivot shaft location receptacles is in the form of a depression closely approximating the dimension and geometry of the pivot shaft locator member  92 , but the location receptacles are designed to provide for precision location of the pin  92  with respect to the mount base. The receptacles are of slightly oblong configuration as compared with the circular cross-sectional configuration of the end portions  91  and  93  of the locator pin, thereby defining centering surfaces on each side of each receptacle. These centering surfaces guide the pivot shaft locator pin  92  precisely to a predetermined position establishing the pre-set zero condition of the sight mechanism. Each of the pivot shaft location receptacles define opposed pin centering surfaces that ensure precise rotational positioning of the pivot shaft locator pin  92  with respect to the upstanding boss  64 . The receptacles are preferably relieved in depth so that the pivot pin engages the receptacle surfaces at opposed side portions thereof which serve to guide the pin to its precisely centered position within the receptacle. This feature ensures precise positioning of the sighting device at the operative position of the pivot mount mechanism when the sighting device is pivotally returned to its operative position. This feature ensures precision positioning of the pivot shaft with respect to at least the first pair of pivot shaft location receptacles  86  and  88  to establish the precision sighting position of the pivot shaft, sight support and the sighting device that is controlled by rotation of the pivot shaft. With the pivot shaft locator pin  92  located within either selected pair of pivot shaft location receptacles rotation of the pivot shaft is restrained against inadvertent rotational movement. This feature ensures that the sighting device and its support will be substantially immovable at both its operative and inoperative positions. When the sighting device is located at its laterally offset inoperative position, it will be secured by the pivot mount against any inadvertent movement and thus will not move about or tend to create any noise. This is an important feature promoting the tactical application of the pivotal sight positioning mechanism. 
     To permit pivot shaft rotation the pivot shaft  76  is moved linearly within the bores  68  and  70  of the upstanding pivot bosses  64  and  66  sufficiently to disengage the ends  91  and  93  of the pivot shaft locator pin  92  from an aligned pair of pivot shaft location receptacles and move the ends of the pivot shaft locator pin beyond the inner end surface  65  of the upstanding pivot boss  64 . At this point the pivot shaft  76  is free for rotation, though under the influence of the compression spring  80 , and may be rotated through an increment of at least 90°. Linear movement of the pivot shaft is caused by application of manual force against the force of the compression spring  80  as is explained in greater detail below. When this manual force is released the compression spring will tend to move the pivot shaft toward the pivot boss  64 . When the ends  91  and  93  of the pivot shaft locator pin  92  are in registry with either pair of pivot shaft location receptacles and the manual force overcoming the spring force has been relieved, the force of the compression spring  80  will move the pivot shaft linearly and seat the ends of the pivot shaft locator pin within the pivot shaft location receptacles, preventing rotation of the pivot shaft. Depending on the position of the locator pin ends with respect to the pivot shaft location receptacles, the spring force may cause the locator pin ends to engage the boss surface  65 . When the locator pin ends are in engagement with the surface  65  the sight support member  96  and its sight device can be manually rotated until the ends of the pin are forced by the compression spring to enter into a selected pair of locator receptacles and secure the mechanism against inadvertent rotation. 
     A sight support device  96  defines pivot section  98  and is located within the space or slot  69  between the pivot boss surfaces  65  and  67 . The sight support device is of smaller axial dimension as compared to the dimension of the space or slot between the pivot boss surfaces  65  and  67 , thereby permitting linear movement of the sight support device within the space, such linear movement being sufficient to extract the ends  91  and  93  of the pivot shaft locator pin  92  from the pivot shaft locator receptacles to permit shaft and sight support device rotation. The sight support device  96  defines a bore  100  shown in the sectional view of  FIG. 11  through which the pivot shaft  76  extends and within which the sight support device is secured against movement. 
     It is necessary for optimum sighting accuracy of the firearm that the sight support device  96  be disposed in fixed relation with the pivot shaft. One suitable means for accomplishing this requirement takes the form of roll pins  102  and  104  that are positioned within transverse bores  106  and  108  of the sight support device  96  and extend in close fitting relation through holes  105  of the pivot shaft  76 . Another means for accomplishing this requirement may take the form of a splined retention mechanism. Any other system for securing the sight support device  96  in substantially fixed relation with the pivot shaft may be employed within the spirit and scope of the present invention. 
     The sight support device  96  defines ring sections  110  and  112  that define a generally cylindrical opening  114  that is sized to fit closely with the cylindrical barrel portion of a sighting device such as shown at  18  in  FIG. 1 . Each of the ring sections defines an enlargement  116  and  118  which, in absence of retainer forces drawing them together, defines a gap  120 . The enlargements  116  and  118  are machined to define openings  122  and  124  within which are located hardened internally threaded inserts  126  and  128 . Screws  129  or other suitable retainer devices are received within the inserts and are tightened to draw the enlargements toward one another and develop a clamping activity establishing sufficient frictional gripping relation to secure the sighting device against inadvertent movement within the cylindrical opening  114 . The ring sections  110  and  112  are somewhat flexible, even though composed of a metal material such as aluminum, steel, titanium or other suitable metal or non-metal materials. When the screws or other retainer devices are tightened the ring sections  110  and  112  are flexed, thus closing the gap  120  to a certain extent and causing the ring sections to establish a clamping or gripping relation with the barrel of a sighting device to secure it against movement relative to the sight mount ring device  96 . 
     OPERATION 
     A lever actuated sight mount rail clamp mechanism  26  in the form of a pivot mount, with its locking lever  48  rotated to its unlocked or release position is selectively positioned in assembly with the Picatinny rail or with other sight mount rail of the firearm, with the mount location key  29  engaged within a selected transverse groove or slot of the rail, thus positioning a sighting device  18  as desired relative to the receiver of the firearm. The locking lever is then rotated to its locking position, causing the tapered cam surface  45  of the cam plate  46  to establish clamping engagement with a downwardly facing angulated locking surface  37  of the sight mounting rail  11 . This cam actuated clamping activity causes downwardly facing angulated rail surfaces  32  and  34  to be drawn into tight clamping engagement with upwardly facing angulated rail surfaces  33  and  35 . The lever and cam actuated clamping activity also causes precise centering of the sight mount rail clamp mechanism  26  on the sight mount rail so that the sighting device  18  is secured at its previously sighted zero position relative to the sight mounting rail and other firearm components. This feature, presented in detail in the disclosure of U.S. Pat. No. 7,272,904 of LaRue, permits firearm users to efficiently remove and replace the sighting devices of a firearm without losing the previously sighted zero. A firearm employing this sight mount clamping mechanism may be transported with one or more sighting devices removed from the firearm and protected in the user&#39;s tactical travel pack. This feature is especially important and beneficial when the firearm is being manually transported during tactical maneuvers, especially at night or during inclement weather conditions. When a site of firearm use is reached, the user will simply remove the sight and mount assemblies for the tactical travel pack and lock the sighting devices in place on the rail mounting system of the firearm. The firearm will be ready to sight and fire accurately when the sighting devices are installed in this manner. 
     Assuming that the pivot mount mechanism  26  is located at its operative position as shown in  FIGS. 1 and 2 , and it is desired to move the sighting device  18  to a laterally offset out of the way position, the user will grasp the sight support device  96  and the sighting device  18  and apply sufficient manual pulling force. When the pulling force is sufficient to overcome the force of the compression spring  80 , the pivot mount mechanism will be moved linearly and rearwardly sufficient to extract the ends  91  and  93  of the pivot shaft locator pin  92  from the pivot shaft location receptacles  86  and  88 . After this linear retracting movement of the sight mount ring device  96  and the sighting device  18  has been accomplished a manual rotational force is applied to rotate the sight support device  96  and the sighting device  18  toward a laterally offset position. After slight rotational movement of sight mount ring device  96  has occurred the pulling or retracting force can be dissipated, causing the ends  91  and  93  of the pivot shaft locator pin  92  to be in supported engagement with the inner end surface  65  of the upstanding pivot boss  64  as shown in  FIGS. 9 and 11 . Manual rotation of the sight support device  96  from this position will simply cause the ends of the pivot shaft locator pin  92  to slide along the inner end surface  65   
     Rotation of the sight support device  96  and the sighting device  18  can be continued until the ends  91  and  93  of the pivot shaft to move into registry with the second pair of generally vertically aligned pivot shaft location receptacles  87 - 89 . At this point the force of the compression spring  80  will drive the pivot shaft toward the pivot boss  64 , causing the ends  91  and  93  of the pivot shaft to engage within the second pair of shaft location receptacles  87  and  89  and lock the pivot shaft, sight mount ring device and sighting device against rotation from the laterally offset inoperative position. At this inoperative position the sighting device will be secured against any inadvertent movement and thus will not make any noise when the firearm is moved from one position to another. 
     Returning the sighting device to its operative position is accomplished simply by applying a pulling or retracting force to the sight support device  96  and the sighting device  18  and rotating the sighting device to its operative position, whereupon the spring force will again seat the ends of the pivot shaft locator pin  92  within the first pair of generally horizontally oriented receptacles  86  and  88 . 
     In view of the foregoing it is evident that the present invention is one well adapted to attain all of the objects and features hereinabove set forth, together with other objects and features which are inherent in the apparatus disclosed herein. 
     As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its spirit or essential characteristics. The present embodiment is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.