Abstract:
Described herein is a removable sight level for a firearm. The sight level includes a lower clamp member. Also disclosed is an upper clamp member attached to the lower clamp member. A level indicator holder having a plurality of level indicator holder voids aligned with the upper clamp member voids is adjustably attached to the upper clamp member. At least one fastener may be utilized, at least partially within one of the level indicator voids and partially within one of the upper clamp member voids being tensionable there between so as to selectively prohibit movement between the upper clamp member and the level indicator holder. At least one of the voids is elongated and has a radially convex surface so as to allow selective arcuate movement between the upper clamp member and the level indicator holder when the fasteners are not tensioned.

Description:
RELATED APPLICATIONS 
     This application, U.S. patent application Ser. No. 13/797,465 filed Mar. 12, 2013, claims benefit of U.S. Provisional Patent Application Ser. No. 61/751,786 filed Jan. 11, 2013. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     Field of the Disclosure 
     This disclosure relates to the field of firearm sights and sighting appendages. 
     SUMMARY OF THE DISCLOSURE 
     Disclosed herein is a removable sight level for a firearm comprising: a lower clamp member having a first end and a second end. Also disclosed is an upper clamp member having a first end attached to the first end of the lower clamp member, a second end attached to the second end of the lower clamp member, and a plurality of upper clamp member voids parallel to a sight axis of the firearm. A level indicator holder having a plurality of level indicator holder voids aligned with the upper clamp member voids is positionably attached to the upper clamp member. At least one fastener may be utilized, at least partially within one of the level indicator voids and partially within one of the upper clamp member voids being tensionable there between so as to selectively prohibit movement between the upper clamp member and the level indicator holder. At least one of the voids is elongated and has a radially convex surface so as to allow selective arcuate movement between the upper clamp member and the level indicator holder when the fasteners are not tensioned. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of one example of the apparatus attached to a highly schematic sight and firearm. 
         FIG. 2  is an isometric view of the example shown in  FIG. 1  removed from the sight and firearm. 
         FIG. 3  is a detail enlarged view of one component of the apparatus shown in  FIG. 2 . 
         FIG. 4  is a detail view of the apparatus shown in  FIG. 2  from a different angle. 
         FIG. 5  is a detail enlarged view of one component of the apparatus shown in  FIG. 2 . 
         FIG. 6  is an exploded view of the main components of the apparatus. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Firearms are commonly equipped with sighting apparatuses, such as aiming scopes, mounted above barrel of the firearm. These sighting apparatuses perform best when two planes, a plane defined by a line through the center of the gun barrel and the sight line of the scope, which will be referred to as the shooting plane, and a second plane defined by a line through the center of the firearm barrel and a line perpendicular to the horizon, which will be referred to as the vertical plane, are coincident, or, in other words, lie in the same plane. 
     Reticle lines or “cross hairs” in the viewing area of common scope style sighting apparatuses facilitate alignment of the shooting plane with the vertical plane. When the sighting apparatus is installed on the firearm, it is positioned substantially on top of and centered vertically above the firearm barrel. A vertical cross hair in the sight viewing area is aligned so that an extension of the cross hair in the direction of the gun barrel would pass through the centerline of the gun barrel. Thus, the vertical cross hair is a visual indicator of the shooting plane of the firearm. 
     By looking through the firearm scope and comparing the vertical cross hair to an object appearing in the sight known to be vertical, such as the side of a tall building, or alternately comparing the horizontal cross hair in the sight to a known horizontal object, such as the horizon, the user receives visual confirmation that the shooting plane is aligned with the vertical plane. This plane alignment is commonly called “plumb”. 
     In many circumstances, however, a good horizontal or vertical visual reference is not available, and the firearm operator can only estimate the vertical plane. The known prior art proposes several level or plumb indicating devices to assist in finding the vertical plane. Bubble levels and electronic devices for both in-sight and out-of-sight indication are some examples commercially available. In-sight indicators show the reference to vertical within the viewing area of the sighting apparatus, while out-of-sight indicators show the reference to vertical outside the scope viewing area. 
     In-scope indicators are typically complex, expensive and can detract from the original telescopic viewing/aiming design of the sighting apparatus. Such in-scope indicators are often difficult or impossible to add to the scope sighting apparatus) after manufacture of the scope as an after-market, add-on product. Out-of-sight indicators can be complex and/or expensive, but also can have additional problems, such as being located on the scope in a poor viewing position, thus being difficult for the operator to see while shooting, or being physically unprotected from damage, especially while the firearm is being carried and not used for shooting. 
     Prior art out-of-sight level indicating devices are commonly attached to sighting apparatus using half round collars or straps that employ fasteners at both strap ends to connect the strap to the rest of the device. This configuration of strap and fasteners often mandates ends on the strap that are often too large to fit between many sighting apparatuses and the firearm, thus requiring the user to remove the sighting apparatus from the firearm to install the level indicating device. 
     Removing and re-installing a sighting apparatus can be tedious and time-consuming. Thus, it is desirable to avoid removal and re-installation of the sighting apparatus, such as when adding accessories, such as a sight level. When fastening a level indicating device to a sighting apparatus, it is often difficult to precisely maintain the desired relationship between the shooting plane and a level position of the level indicating device. As the fasteners are tightened, the level indicating device tends to move on the scope, thus losing the desired alignment of the level indicating device. 
     Referring to  FIG. 1  a highly schematic scope  22  is shown mounted above a highly schematic shortened section of a firearm  24 . The sighting apparatus (scope  22 ) is mounted to the firearm  24  by way of offset mounts  26  which generally keep the outer surface  32  of the scope offset from the adjacent surface of the firearm. In this example, a level indicating device  20  is shown mounted on scope  22 . In this disclosure, the term scope is used generally interchangeably with the term sighting apparatus, as both are substantially equivalent relevant in many functional respects. 
     Before continuing a detailed description, an axes system  10  is disclosed, generally comprising a longitudinal axis  12  aligned with and parallel to the sight axis  18  of the scope  22  as well as a vertical axis  14  and a transverse axis  16  orthogonal to the vertical axis  14  and longitudinal axis  12 . These axes are intended to aid in description and are not intended to limit the apparatus to a particular operating orientation. 
     Reticule lines or “cross hairs”  28  within the viewing area of the scope  22  facilitate alignment of the shooting plane with the vertical plane. When the sighting apparatus  22  is installed on the firearm  24 , a vertical cross hair  34  in the sight viewing area represents the shooting plane and is aligned so that an extension of the vertical cross hair toward the gun barrel would pass through the centerline  52  of the gun barrel. The horizontal cross hair  40  is orthogonal to the vertical cross hair  34  and to the sight axis  18 . Thus, the vertical cross hair is a visual indicator of the shooting plane of the firearm. 
     In use, as previously mentioned, the shooter aims the firearm  24  at a target while looking at the target through the scope  22 . While doing so, the shooter attempts to hold firearm  22  and attached scope  22  such that the shooting plane  30  and vertical plane  14  are aligned. By looking through the firearm scope and comparing the vertical cross hair  34  to a distant object appearing in the sight known to be vertical, such as the side of a tall building, a tree, fencepost, or alternately by comparing the horizontal cross hair  40  in the sight to a known horizontal object, such as the horizon above a large body of water, the user receives (interprets) visual confirmation that the shooting plane is aligned with the vertical plane, or the shooting plane. 
     When a horizontal or vertical visual reference is not available, without a level indicating device the firearm user can only estimate the vertical/horizontal planes. With the aid of a level indicating device, such as the level indicating device  20  shown in the Figs, the user no longer has to estimate the vertical plane, as the vertical plane  14  is visually represented by a level indicator (bubble vial)  36  on the level indicating device  20 . In the case of the embodiment of the level indicating device  20 , the indicator is a gravity driven bubble  38  in a typical level indicator  36 . The level indicator component may alternatively be an electronic device with lights and/or audio tones which indicate to the shooter that the shooting plane is plumb. Electronic indicators can be driven by liquid level sensor(s), pendulum(s) with proximity sensor(s), magnetic field sensor(s), mercury switches, or electronic components and circuitry. 
     The component of the level indicating device that actually does the sensing may be constructed to sense either horizontal or vertical planes, but for this application, the level indicator (bubble vial  36 ) indicates the horizontal plane and is integrated into the level indicating device  20  such that when the level indicating device  20  indicates a level or plumb orientation of the firearm  24  to the firearm operator, the level indicating device indicates to the firearm operator that the shooting plane is aligned with the vertical plane. For example, the level indicating device  20  in  FIG. 1  contains bubble level vial  36 , which indicates to the user when bubble level vial  36  is positioned in a horizontal plane, by the presence of a bubble  6  appearing substantially centered between two lines  48  on bubble level vial  36 . This orientation of the bubble between the lines indicates that the shooting plane is aligned with the vertical plane which, as previously described, is normally desired for accurate shooting of the firearm  24 . If the level indicating device  20  is attached to the scope  22  such that the horizontal plane containing the long axis centerline of level indicator  36  is perpendicular to the shooting plane  30 , then an indication of level in level indicator  36  is also an indication that the shooting plane  30  is aligned with the vertical plane. 
     The example of the sight level indicator shown in  FIG. 1  generally comprises a lower clamp member  42  removably attached to an upper clamp member  44  as will be described. A level indicator (bubble vial) holder  46  holding the level indicator  36  is attached to the upper clamp member, such that the angle of the level indicator  36  to the transverse plane  16  may be adjusted. In a proper shooting orientation, the air or gas bubble  38  of the level indicator  36  should be centered between level indicators  48 . Level indicators  48  may be printed or engraved on the bubble vial  36 , or on the level indicator holder  46 . Relative to the sight axis  18 , the bubble level holder has a radially inward end  50  and a radially outward end  52 . 
     In one form as shown in  FIG. 1 , a first end  54  of the lower clamp member  42  has a maximum thickness  56  which is less than the offset distance  58  between the firearm  24  and the outer surface  32  of the scope  22 . This difference allows the sight level indicating apparatus  20  to be attached without removal of the scope  22 . 
     Looking to the example shown in  FIG. 2 , the first end  54  of the lower clamp member  42  is attached to the upper clamp member  44  by way of a cylinder and socket joint  60 . The joint  60  comprises a cylinder  62  of the lower clamp member  42 , and a socket  64  formed in the cooperating first end  66  of the upper clamp member  44 . 
     In the example shown in  FIG. 6 , the cylinder  62  and the socket  64  each have a gap  68 / 70  respectively formed between longitudinal sub-portions thereof. The formation of these sub-portions and gap results in the cylinder  62  being formed of a plurality of fingers  72  having a thickness slightly less that the width of the gap  70 . Likewise, the socket  64  may be formed of a plurality of fingers  74  having a thickness slightly less that the width of the gap  68 . In this way, the fingers of the socket  64  fit substantially vertically through the gap  68 , the fingers of the cylinder  62  fit through the gap  70 , and thus less longitudinal movement is required to connect the cylinder and socket joint to the position shown in  FIG. 2 . This assembly arrangement may be very helpful if there is limited space between the scope  22  and firearm  24 . 
     In the Example of  FIG. 6 , the second end  80  of the lower clamp member  42  is attached to the second end  82  of the upper clamp member  44  by way of fasteners  84  passing through clearance holes  86  and engaging threaded holes  88 . In one form, threaded holes  88  may be provided on the opposing surface of the upper clamp member  44  as threaded nuts or similar elements. Once fastened, these fasteners  84  put the inner surface of the clamp members  42 / 44  in compression about the sighting apparatus  22 . Other compression fasteners could also be utilized. The relative position of the threaded holes  88  and clearance holes  86  may be reversed. 
     Once the clamp member comprised of clamp members  42 / 44  is attached to the firearm, it is likely that the level indicator  48  is not initially properly aligned. Thus, it may be desired for minimal/fine adjustment of the level indicator  48  relative to the clamp member(s)  42 / 44 . This fine adjustment is accomplished as shown below. 
     Still looking to  FIG. 6 , it can be seen that the radially outward surface  90  of the upper clamp member  44  in this example comprises a projection  92  having a plurality of surfaces defining threaded voids  94 / 96  therein. The threaded voids align with surfaces defining elongate voids  98 / 100  (see  FIG. 3 ) in the level indicator holder  46 . When fasteners  106 / 108  are threaded and sufficiently tensioned in place within the voids  94 / 96 / 98 / 100 , the level indicator holder  46  is held in relative position to the upper clamp member  44 . In one form, inner surfaces  110  of projections  112  ( 112 ′/ 112 ″) slide along the projection  92  when tension is not provided by the fasteners  106 / 108 . As the fasteners  106 / 108  are tensioned, the projections  112  deform towards and frictionally engage the longitudinal sides of the projection  92 . Radially inward surfaces  116 / 118  of the projections  112  may ride upon radially outward surfaces  120 / 122  of the upper clamp member. In one example, relief cuts  114  may be provided in line with inner surfaces  110  to allow a more free movement of the projections  112  than would be allowed otherwise. This the relief cuts  114  provide a more face to face clamping force between the surfaces  110  as the axis of pivot will be moved away from the intersection of the surfaces  110  with the surface  116 . 
     The surfaces defining voids  98 / 100  in one example are radially elongated in that their length in a tangential direction is larger than their length in a radial direction. In addition, the voids  98 / 100  have a concave surface  102  and a convex surface  104  having substantially the same axis of curvature so as to allow the level indicator holder  46  a few degrees of rotation relative to the upper clamp member  44 . In one example, the center of curvature of these two surfaces is substantially the sight axis  18  of the scope  22 . In a more general form, the center of curvature may be within the outer surface  32  of the scope  22 . In one form, rotation of 90° or more may be possible, while rotation between 2° and 30° (or in a narrower range between 5° and 15°) may be sufficient assuming that the person installing the clamping members is sufficiently capable. 
     As can be better understood by looking to  FIG. 3 , the voids  98  in the first longitudinal projection  112 ′ are circumferentially offset from the voids  100  in the second longitudinal projection  112 ″. Likewise, the voids  94  are circumferentially offset from the voids  96 . As the projection  92  may be relatively thin longitudinally, it may be desired to allow for as much longitudinal space as possible for the threads of the fasteners  106 / 108  if the voids  94 / 96  are threaded. Thus, in one example the fasteners  106  pass through the voids  98  into threaded voids  94 , while fasteners  108  pass through voids  100  into threaded voids  96 . This radially offset void arrangement allows for the fasteners  106 / 108  to engage more of the projection  92  than would be possible if the threaded voids  94 / 94  were axially aligned. 
       FIG. 6  also shows another example of the level indicator holder component  46 ′.  FIG. 5  shows this level indicator holder component  46 ′ in more detail. In this example, the convex surface  104 ′ and concave surface  102 ′ of the elongate void  124  have a radius of curvature  132  centered upon a cylindrical void  126 . In this example, once the inner surfaces  128  and  130  of the upper and lower clamp members  44  and  42  respectfully are frictionally engaged to the outer surface of the scope  22 , the level holder component  46 ′ is attached if needed, and adjusted by rotation of the level indicator holder component  46 ′ about fasteners passing through the voids  126 / 94  while the firearm is in a vertical position so that the shooting plane is aligned with the vertical plane. Once correctly positioned, fasteners  106  which pass through or are threaded into voids  126 / 94  and fasteners  108  which pass through voids  124 / 96  are then tensioned as with the previous example. Once these fasteners  106 / 108  are tensioned, the level indicator is held and fixed in the correct orientation. 
     As can be seen in  FIG. 4 , the level indicator  36  may be held within a cavity  136  of the level holder component by way of a retaining ring  134 . In another example, the level indicator  36  may be held in place by a set screw, adhesive, press fit or other methods. The retaining ring  134  is also shown in  FIG. 6  alongside the level indicator  36 . To add functionality to the apparatus in low light situations, a light module  138  may be provided along with a power module  140  such as a battery. The light module  138  may be pressure sensitive, such that when a user pressed upon the outward end  142  of the apparatus, the light module  138  is activated and the level indicator  36  is illuminated for night or low light operations. The light module may alternatively be light activated, have an external switch, be capacitive sensing or otherwise activated. 
     While the present invention is illustrated by description of several embodiments and while the illustrative embodiments are described in detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the scope of the appended claims will readily appear to those sufficed in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicants&#39; general concept.