Abstract:
The present invention improves leveling of accessories mounted on a rail on a firearm. The improved rail includes a level housing configured at a proximal end of a Picatinny Rail. The level housing compress a generally rectilinear body having a viewing window configured on a front edge of the body. The body defines a volume adapted to receive a spirit level. The volume further includes a back wall arranged at substantially about 45-degrees incident to a viewing plane. 
     The housing further includes an undersized opening on a first sidewall, which is configured to restrict the level from escaping the volume. A second sidewall arranged substantially parallel to the first sidewall includes an oversized opening further configured to slideably receive the spirit level, which is retained in place by a lock-ring.

Description:
PRIORITY CLAIM 
       [0001]    The present application is based on, and claims priority to for all purposes, co-pending provisional patent application No. 61/948,751 filed on 6 Mar. 2014 having the common inventor named above. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates generally to hand-held firearms, and particularly concerns both devices and methods for precisely aligning the vertical cross hair of the reticle system of an attached sighting scope to be parallel to a symmetry axis of the firearm that is vertical and perpendicular to the firearm bore. 
       BACKGROUND 
       [0003]    Sighting scopes, both those that magnify the sight field and those that incorporate reticles (but do not magnify the sight field), are traditionally mounted on their respective rifle, pistol, or shotgun (collectively “firearm”) by means of cooperating mounting rings attached to the receiver of the firearm. The sighting scopes include reticles, which are a system of lines, dots, cross hairs, wires, or electrically projected images that aid in the sighting of a target and proper positioning the firearm relative to a target. A common reticle system is comprised of intersecting cross hairs consisting of a vertical and horizontal cross hair. 
         [0004]    Often, when a scope is mounted to the firearm using the scope-mounting rings attached to the firearm&#39;s receiver, the scope is mounted off-center relative to the true axis defined by the bore of the barrel and is therefore canted or rotated to some degree resulting in misalignment of the cross hair on the scope relative to the symmetry axis of the firearm that is vertical and perpendicular to the firearm bore. 
         [0005]    Shooters, especially competition target shooters, tend to compensate for the included cross hair canting by counter-rotating the firearm and thus compromise the accuracy of this shot. 
         [0006]    Accordingly, it is very important that the scope&#39;s cross hair alignment system be in precise alignment with the corresponding axis of the firearm, which will result in a more accurate and more repeatable shot. Further, such a system should be easy to use, visible in low light and bright light conditions, be economical to produce, robust and hardy in design, and simple to mount to the weapon. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention incorporates a conventional tactical rail, also known as a Picatinny Rail (MIL-STD-913), and adapts it to further include a unique bubble-level (float level). 
         [0008]    The present invention adapts a conventional Picatinny rail. First, as those skilled in the art will appreciate, a Picatinny rail includes a curved or flat underside, configured to contour to common rifle barrels and or receivers. And the top surface includes a plurality of parallel ridges, the series of ridges further include either a “V”-shaped or a “T”-shaped cross-section interspersed with flat “spacing slots.” Accessories are mounted either by sliding them on from one end or the other and fixing the accessory using the ridges and shoulders (the V-shape or T-shape profile associated with the ridge). In addition to the Picatinny rail-optimized accessory, a Weaver mount attaching scheme can be also used. In this case the accessory (such as a scope) is clamped to the rail with bolts, thumbscrews or levers. Alternatively, accessories engage one or more of the slots formed between the ridges. 
         [0009]    The present invention incorporates a conventional Picatinny rail, which includes a slot width spacing of substantially about 0.206-inches (5.23 mm). The spacing of slot centers is 0.394 in (10.01 mm) and the slot depth is 0.118 in (3.00 mm). Between each slot, a ridge stands proud and the actual width of the ridge may vary. In addition to the features found in a conventional Picatinny rail, the present invention includes, at a proximal end, a housing configured to receive a spirit-type “bubble” level. This housing is fabricated from the same, continuous piece of raw stock aluminum block, and both the housing and conventional Picatinny rail features (at the distal end) are machined during fabrication. 
         [0010]    The housing is configured to receive and encapsulate a unique spirit level (also called a bubble level or simply a level), which is an instrument designed to indicate whether a surface is horizontal (level) or vertical (plumb). In this application the level is oriented to determine horizontal leveling of the accessory attached to the rail. 
         [0011]    The level consists of a slightly curved glass tube that is incompletely filled with a liquid such as a colored spirit or alcohol, leaving a bubble in the tube. At slight inclinations the bubble travels away from the center position, which is usually marked. 
         [0012]    Alcohols such as ethanol are often used rather than water. Alcohols have low viscosity and surface tension, which allows the bubble to travel the tube quickly and settle accurately with minimal interference with the glass surface. Alcohols also have a much wider liquid temperature range, and won&#39;t break the vial as water could due to ice expansion. A colorant such as fluorescein, typically yellow or green, may be added to increase the visibility of the bubble. 
         [0013]    To further aid in light reflectivity of the level, the housing includes open ends on the front and back. Further, a polished machined surface inclined substantially about 45-degrees relative to the viewing window serves as a back wall behind the vial. This concentrates and reflects more light toward the user, making the present invention highly readable even in low-light conditions. 
         [0014]    The present invention would work equally well by similarly adapting a Weaver rail, NATO-standard rail, or one-piece rail mount with a dove-tail, or holes with screw or other fastener mount or side clamps to hold rings. The primary difference between the Picatinny rail and a Weaver rail is the size of the slots: Weaver rails have a slot width of 0.180 in (4.57 mm), but are not necessarily consistent in the spacing of slot centers. 
         [0015]    One contemplated embodiment of the present invention includes an improved leveling device for rifle accessories utilizing a Picatinny Rail the improved leveling device comprises a level housing configured in a proximal end of the Picatinny Rail, the level housing comprising a generally rectilinear body having a viewing window configured on a front edge of the body, the body defining a volume adapted to receive a spirit level, the volume further including a back wall arranged at substantially about 45-degrees incident to a viewing plane; 
         [0016]    The level housing further comprising an undersized opening on a first sidewall, the undersized opening configured to restrict the spirit level from escaping the volume adapted to receive the spirit level and an oversized opening on a second sidewall, the second sidewall configured substantially parallel to the first sidewall and wherein the first and second sidewall are substantially perpendicular to the viewing window, the oversized opening further configured to slideably receive the spirit level; and 
         [0017]    A lock-ring is configured to engage the oversized opening whereby the spirit level is restricted from escaping the volume. 
         [0018]    In another contemplated embodiment, the present invention contemplates a device for a rifle, the device comprising: 
         [0019]    a Picatinny or Weaver rail or one-piece rail with a dovetail cross slot comprising a plurality of mounting holes and a plurality of interspaced ridges and slots, the rail having a proximal end consisting of a level housing; 
         [0020]    The level housing comprising a generally rectilinear body having a viewing window configured on a front edge of the body, the body defining a volume adapted to receive a spirit level, the volume further including a back wall arranged at substantially about 45-degrees incident to a viewing plane; 
         [0021]    The level housing further comprising an undersized opening on a first sidewall, the undersized opening configured to restrict the spirit level from escaping the volume adapted to receive the spirit level and an oversized opening on a second sidewall, the second sidewall configured substantially parallel to the first sidewall and wherein the first and second sidewall are substantially perpendicular to the viewing window, the oversized opening further configured to slideably receive the spirit level; and 
         [0022]    A lock-ring is configured to engage the oversized opening whereby the spirit level is restricted from escaping the volume. 
     
    
     
       DRAWING 
         [0023]      FIG. 1  is a top view of a preferred embodiment of the present invention. 
           [0024]      FIG. 2  is a side view of the embodiment of  FIG. 1 . 
           [0025]      FIG. 3  is a cross-sectional view along the line  3 - 3  of  FIG. 1 . 
           [0026]      FIG. 4  is a cross-sectional view along the line  4 - 4  of  FIG. 1 . 
           [0027]      FIG. 5  is an offset frontal view of the embodiment of  FIG. 1 . 
           [0028]      FIG. 6  is a partial front view detailing the level housing on a modified Picatinny Rail according to a preferred embodiment of the present invention. 
           [0029]      FIG. 7  is a partial side view of the level housing of  FIG. 6 . 
           [0030]      FIG. 8  is side view of the rail device of  FIG. 1  and depicts system using the rail device. 
           [0031]      FIG. 9  is a cross-sectional side view of the level housing portion of the rail device of  FIG. 1  along the line  9 - 9  of  FIG. 6 . 
           [0032]      FIG. 10  is a representational view illustrating a preferred angle of the back wall of the level housing of  FIG. 9 . 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0033]    Possible embodiments will now be described with reference to the drawings and those skilled in the art will understand that alternative configurations and combinations of components may be substituted without subtracting from the invention. Also, in some figures certain components are omitted to more clearly illustrate the invention. 
         [0034]    Although the present invention is discussed relative to a Picatinny rail, those skilled in the art will appreciate that the design, spirit, and scope of the invention can readily be adapted to other mounting systems, and this discussion, accordingly, should not be limiting. A Picatinny rail is also known as a MIL-STD-1913 rail and is a bracket that provides a standard mounting platform for accessories and attachments. Similarly, a Weaver rail mount, which uses a pair of parallel rails and several slots perpendicular to these rails, is partly compatible with the Picatinny rail—and accordingly, the teachings of the present invention are readily adaptable to a Weaver rail including older Weaver systems that use two pieces mounted a distance apart from one another, typically on the receiver of a rifle over the bolt opening where the cartridge would be inserted and/or ejected. And, the present invention can be readily adapted to a NATO Accessory Rail (NAR), which is backwards compatible with the Picatinny rail. 
         [0035]    Some limitations of rail mounting systems that are overcome by using the present invention with a Picatinny rail can be overcome without detracting from the spirit and scope of the present invention. For example, the slots on a Weaver rail system have a slot width of 0.180 in (4.57 mm), but are not necessarily consistent in the spacing of slot centers. 
         [0036]    The improved rail device  10  of the present invention greatly improves over the state of the art and eliminates problems associated with conventional scope mounting. The improved rail device provides windage and elevation calibration allowing a shooter to optically center the reticle for maximum performance from a mounted riflescope S (in  FIG. 8 , for example). As  FIG. 8  shows, in one preferred embodiment the improved rail device  10  includes two Leupold Mark 4 rings (R 1  and R 2 ) to compliment the rail mount. Additionally, the improved rail device includes a 20 MOA forward slope, which enables the improved rail device to be machined and combined with a sine bar to allow for a neutral to 25 MOA forward slope quickly and easily, and shims, (not shown) if required, are understood to be included in this system. 
         [0037]      FIGS. 1-10  illustrate a first preferred embodiment of the present invention. The present invention comprises an improved rail device  10  for improved alignment of accessories mounted to a firearm, such as a rifle. The improved rail device is suitably configured to enable perfect alignment for a scope or other accessory for a firearm. The improved rail device includes a plurality of rail mounting features as would be understood in conventional rail mounting devices, such as a Weaver rail or Picatinny rail, or NATO rail and includes a rail body  12  having a proximal end  13  and a distal end  15 , the proximal end includes a leveling device. By proximal end  13 , I mean that end which faces the shooter when targeting a scope mounted on a rifle, for example. 
         [0038]    In one preferred embodiment, the present invention includes many of the features of a conventional Picatinny rail. And, accordingly, the present invention includes a slot width spacing of substantially about 0.206-inches (5.23 mm). The spacing of slot centers is 0.394 in (10.01 mm) and the slot depth is 0.118 in (3.00 mm). A first plurality of slots arranges at the proximal end of the body of the present invention, a second plurality of slots arranges at the 13 distal end of the body of the present invention and an intermediate bridge portion  17  arranges intermediate to the proximal  13  and distal  15  ends. 
         [0039]    The leveling device includes a level-housing  30  configured at the proximal end  13  of the rail body  12 . The level housing includes a reflective illumination feature the produces the brightest scope level using ambient light. The level housing further includes a canted direction that enable a shooter to use the level bubble from a shooting position. 
         [0040]    An improved rail mounting system comprises an improved rail device, one or more self-leveling rings, and a conventional scope. The present invention contemplates an improved rail device comprising a rail body  12  comprising a proximal end  13  and an oppositely disposed distal end  15  with an intermediate bridge  17  spanning between the proximal and distal ends. Each respective proximal and distal end comprising a plurality of slots  14  and ridges  16  predictably spaced along a top surface  22  of the rail body, ideally having the characteristics of a Picatinny rail, however, alternative contemplated embodiments adopt other conventional rail arrangements including Weaver or NATO standard rails, for example. 
         [0041]    The proximal end further comprising a level housing, the level housing comprising a front wall  37 , a bottom wall, two opposing sidewalls  34  and  39 , and a rounded top and a window  32  arranges whereby so that a level bubble  50  can be viewed at many useful angles when mounted on a rifle, and a back wall comprising a highly polished surface arranged at substantially about 45-degrees from a vertical plane established by the front wall of the level-housing; 
         [0042]    As will be well appreciated by those skilled in the art, the rail  12  includes a plurality of slots  14  and ridges  16  predictably spaced along the top surface  22  of the rail. Conventional mounting holes  18  are also dispersed, as would be expected. Although this invention discusses a Picatinny Rail, other similar mounting aids could be readily modified to include the improvement of the present invention. The ridges  16 , perhaps best illustrated in  FIG. 3 , which is a cross section of the rail  12  at line  3 - 3  in  FIG. 1 , have a substantially flat top surface and opposing shoulders to which an accessory may be configured to attach. 
         [0043]    Making specific reference to  FIGS. 1 ,  2 , and  5 , the level-housing  30  arranges on the proximal end  13  of the rail  12 . The level-housing  30  includes a front wall  37 , a bottom wall, two opposing sidewalls  34  and  39 , and a rounded top. A window  32  arranges so that a level  50  can be viewed at many useful angles when mounted on a rifle. 
         [0044]      FIGS. 5-9  further detail the level-housing  30 . A first sidewall  29  includes an undersized opening  38  that is sized so that a level  50  cannot escape the opening. However, the opening should be sufficiently large to let as much ambient light into the housing&#39;s chamber. The opposite, or second, sidewall  34  includes an oversized opening  36 , which configures to allow the spirit level  50  slide into the chamber encapsulated by the level housing. A retainer clip  60  configures to secure the level  50  inside the chamber. 
         [0045]    Importantly, the chamber includes a back wall  35  that is angled substantially about 45-degrees relative to a vertical plane established by the front wall of the level housing. This back wall should be machine polished to be highly reflective, whereas the rest of the device  10  may be painted a flat black or other color as dictated by its use. 
         [0046]    With specific reference to  FIGS. 6 ,  9 , and  10 , a level housing—in one particular preferred embodiment includes a window  32 , which is shown in the cross-sectional profile view of  FIG. 9 . This window enables a shooter to clearly view the spirit level bubble from shooting position (The spirit level is not depicted in  FIGS. 9 and 10 ). The angle of this back wall  35  is important and is substantially about 45-degrees relative to a constructed vertical reference line and from a constructed horizontal reference line, which will be further explained in relation to  FIG. 10 , below. As  FIG. 9  illustrates, the back wall  35  arranges at an acute angle relative to a constructed vertical. The angle of inclination of the back wall  35  is depicted as the constructed line marked A-A in  FIG. 9 . A parallel line P 1 -P 1  is constructed offset from this back wall angle inclination reference line A-A as a matter of convenience. A horizontal line OBA-OBA is parallel to, but offset from the bore axis of the firearm; this reference axis is also parallel to the long axis of the rail device  10 . A vertical line V-V is perpendicular to this offset bore axis OBA. With reference to  FIG. 10 , the aforementioned constructed lines are duplicated with the components of the level housing omitted from this view. From this the acute angle of inclination “a” is shown relative to the vertical axis V-V. In one preferred embodiment the angle of inclination “a” (reflecting the orientation of the back wall  35 ) is substantially about 45-degrees: However, those skilled in the art will understand that this angle could range from substantially about 5-degrees to substantially about 85-degrees, depending on many factors. 
         [0047]    The two side openings  36  and  38 , cooperating with the window, and highly polished back wall  35  result in a highly visible level even in low light conditions. 
         [0048]    The level  50  is a conventional bubble level or spirit level that has a bubble  52  and centering lines  54  and works as would be conventionally understood by those skilled in the art. The level  50  is arranged horizontally to establish that the accessory mounted to the rail is level. 
         [0049]    The device  10  is machined from a block of aluminum or steel, stainless steel, carbon fiber, brass or other metals, alloys, or plastics, as would be understood in this art. 
         [0050]    One method of configuring a rifle having a receiver with the improved rail device of the present invention includes the following steps: 
         [0051]    Providing an improved rail device comprising a proximal end with at least one slot and ridge and a distal end with at least one slot and ridge, the proximal end further including a level housing comprising a spirit level, a viewing window configured to enable a shooter to view the spirit level from a shooting position, and the spirit level having a back wall that is arranged at an inclined angle substantially about 45-degrees from a vertical reference line that is perpendicular to the bore axis of the firearm and wherein the rail device includes a proximal base element and a distal base element; 
         [0052]    Attaching the proximal base element to the proximal end of the receiver; 
         [0053]    Attaching the distal base element to the distal end of the receiver; 
         [0054]    Verifying that the top of the distal base element when mounted to the receiver and the top of the proximal base element when mounted to the receiver lie in the same horizontal plane; 
         [0055]    If the tops of the distal base element and proximal base element are not coplanar, shimming one of the base elements to bring both tops into a common plane; (providing one or more shims to enable this); 
         [0056]    Attaching the improved rail device to the respective proximal base element and distal respective element using screws provided including at least one 10-32 flat head cap screw and at least one 10-32 button head screw; 
         [0057]    Providing one or more rings configured to selectively couple to at least one rail on the improved rail device; 
         [0058]    Using a vise, leveling the rifle and base in the vise and hang a plumb obo from a ceiling across the room from the rifle mounted in the vise; 
         [0059]    Placing the scope in the ring halves, snugging the ring caps after aligning the reticle to the string line; 
         [0060]    Providing a collimator and inserting the collimator into the bore and aligning the collimator with the scope reticle; 
         [0061]    Turning the windage dial (left or right) until the reticle stops moving in the collimator; 
         [0062]    Counting the number of clicks or MOA as the windage knob is turned in the opposite direction and taking the number of clicks or MOA and dividing by 2, thus centering the windage adjustment in the erector tube; repeat this for the elevation adjustment; 
         [0063]    With the reticle centered in the scope, removing the scope from the rail and snugging the 10-32 pivot screw on the proximal base element and snugging the 10-32 button head screw on the distal base element; 
         [0064]    Re-attaching the scope and reading the collimator/reticle alignment; shifting or taping the base left or right to align it with the collimator for windage; and tightening the button head screw; 
         [0065]    Using a transfer punch, lightly center punching the location of the front (distal) locking screw in the distal (front) base element; removing the distal base element from the receiver and placing it in a mill vise; 
         [0066]    Locating the center punch mark and center drilling, complete drilling with a #22 drill and tapping a 10-32 tap; 
         [0067]    Cleaning both base elements and refinish if necessary; 
         [0068]    Cleaning the 6-48 tapped holes in the receiver with Acetone and cleaning the 6048 screw; 
         [0069]    Using blue or purple grade of Loctite, applying a small drop to each of the base element base screws; and attaching the respective bases to the receiver and tightening the respective bases to the receiver; and 
         [0070]    Zeroing the rifle conventionally at a range. 
         [0071]    Although the invention has been particularly shown and described with reference to certain embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention.