Abstract:
A firearm accessory mounting rail with an integrated back up sight system including an elongated Picatinny rail having longitudinally spaced apart first and second end regions and a transverse profile. A first sight element has a visual marker substantially centrally positioned. A second sight element has laterally spaced apart visual markers. A substantially centered longitudinal channel extends along the upper surface of the rail between the first and second sight elements. The firearm may be sighted by visually aligning the marker of the first sight element between the markers of the second sight element, the visual alignment being at least partially through the longitudinal channel. The sight elements may be defined completely within the transverse profile of the rail so as not to interfere with the normal attachment of any accessories to the rail and may be adjustable for windage and/or elevation. The visual markers may be illuminated by light gathering fiber optic or tritium elements.

Description:
TECHNICAL FIELD 
     The present invention relates to a rail for mounting optics or other accessories to a firearm, the mounting rail having integral sighting elements. More specifically, it relates to the integration of back-up or “iron” sights into a mounting rail in a manner that does not interfere with the mounting of accessories. 
     BACKGROUND 
     Standardized accessory mounting rails are well known for use with firearms. Most common is the Picatinny, Weaver, or MIL-STD 1913 rail, referred to herein collectively or interchangeably as a “Picatinny” rail or mounting rail. A Picatinny rail can range in length from less than one inch, such as for mounting a light or laser indicator to the underside of a pistol frame or for mounting a single scope ring, to the full length of a rifle. Typically, these standardized accessory attachment rails are formed or secured along the length of the frame, stock, or barrel parallel to the bore of the firearm barrel so that any sighting device, scope, or light is substantially aligned with the barrel either at the top, bottom, or side of the firearm. 
     In some cases, “open” or “iron” sights (sights that do not include any lens or projected beam of light) must be removed or rendered unusable in order to mount an accessory rail. In other cases, the firearm (such as a bolt action rifle) may not have any open sights and sighting is dependent on use of a rail-mounted telescopic or holographic sighting system or the addition of upstanding (or flip-up) iron sight elements. For some users, the consequences of a scope or lighted sight system failure are too great not to have some kind of pre-aligned back up iron sights (BUIS) in place in addition to whatever optics are mounted on the accessory rail. 
     Separate front and/or rear (fixed or flip-up) iron sights can be rail mounted along with a scope or holographic sight in some cases. These, however, add complexity, cost, weight and bulk to the weapon system. Some of these shortcomings are discussed in U.S. Patent Application Publication No. 2008/0092423 by Keng. 
     As another example, a shotgun may be used for hunting with a rail-mounted scope, but may also be used for home defense where a magnifying scope is undesired. Removal of the scope leaves it without any sights unless separate iron sights are installed in its place. Shotguns are also used in military and civilian law enforcement tactics where a need for back up iron sights along with a rail mounted optical sight is present. This need is discussed in U.S. Patent Application Publication No. 2003/0140546 by Kay. In Kay, an elevated rear sight element is integrated with a Picatinny mounting rail. This system raises the sight line a significant distance above the bore axis and requires the addition of a separate, M16-style elevated front sight to the forward end of the barrel. 
     Consideration of the Keng and Kay Patent Application Publications will provide context for and reveal the significance of the present invention. 
     SUMMARY OF THE INVENTION 
     The present invention provides a firearm accessory mounting rail with an integrated back up sight system. It includes an elongated Picatinny rail with longitudinally spaced apart first and second end regions and a transverse profile. A first sight element has a visual marker substantially centered laterally. A second sight element has laterally spaced apart visual markers. A substantially centered longitudinal channel extends along an upper surface of the rail between the first and second sight elements. The firearm may be sighted by visually aligning the marker of the first sight element between the markers of the second sight element, the visual alignment being at least partially through the longitudinal channel. 
     The sight elements may be defined completely within the transverse profile of the rail so as not to interfere with the normal attachment of any accessories to the rail and may be adjustable for windage and/or elevation. The visual markers may be distinctly colored or illuminated by light gathering fiber optic or tritium vial elements. The second sight element can be in the form of an aperture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Like reference numerals are used to indicate like parts throughout the various figures of the drawing, wherein: 
         FIG. 1  is a rear isometric view of a first preferred embodiment of the present invention; 
         FIG. 2  is a rear end view substantially as indicated by line  2 - 2  on  FIG. 1 ; 
         FIG. 3  is a front isometric exploded view of a second preferred embodiment of the invention; 
         FIG. 4  is an assembled view substantially like that shown in  FIG. 3 ; 
         FIG. 5  is a rear isometric view of a third preferred embodiment of the invention showing the inclusion of fiber optic sight elements; 
         FIG. 6  is a detail front isometric view of the front sight element of the embodiment shown in  FIG. 5 ; 
         FIG. 7  is a detail front isometric view of the rear sight element of the embodiment shown in  FIG. 5 ; 
         FIG. 8  is a rear parallel projection view of the embodiment shown in  FIG. 5  as the sight elements are being moved into alignment; 
         FIG. 9  is a rear view of the aligned sight elements taken substantially along line  9 - 9  on  FIGS. 5 and 7 ; 
         FIG. 10  is a detail rear isometric view of an alternate version of the rear sight element shown in  FIGS. 5 ,  7 , and  8 ; 
         FIG. 11  is a rear pictorial view of a fourth preferred embodiment of the present invention; 
         FIG. 12  is a top plan view thereof; 
         FIG. 13  is a rear parallel projection view of the embodiment shown in  FIG. 11  as the sight elements are being moved into alignment; 
         FIG. 14  is a rear view of the aligned sight elements taken substantially along line  14 - 14  on  FIGS. 11 and 12 ; 
         FIG. 15  is a sectional partial isometric view taken substantially along line  15 - 15  of  FIG. 11 ; 
         FIG. 16  is a partial longitudinal view of that shown in  FIG. 15 ; and 
         FIG. 17  is a fragmentary rear isometric view of an alternate rear sight element in the form of an aperture. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the various figures of the drawings and first to  FIG. 1 , therein is shown at  10  an accessory mounting rail with an integrated back up sight according to a first preferred embodiment of the present invention. The rail  10  is an elongated member having a series of laterally-extended lugs  12  with spacing slots  14  there-between. The lugs  12  are supported by a base portion  16  and present a dovetail or chamfered T-shaped profile in cross section. The base  16  may be independent or integrated into a firearm receiver, barrel shroud, stock or other implement. If the rail  10  is a separate fixture and is to be to be secured in place on a firearm, the base  16  may be shaped to engage any desired surface. For example, the bottom surface  17  may be flat or curved to fit closely and firmly onto a corresponding surface. The lugs  12  provide coplanar top surfaces  18  which present a platform on which accessories (not shown), such as an optic device, scope rings, or illumination device may be situated. 
     An accessory is mounted either by sliding it on from one end or by means of a “rail grabber,” which engages the laterally opposite dovetail edges  20  of each lug  12  and is clamped to the rail  10  with bolts, thumbscrews, or levers, or onto the slots  14  between the raised lug portions  12 . The transverse slots  14  allow a fastening member to extend transverse of the mount  10  for releasably gripping the dovetail edges  20 . In this regard, the rail  10  provides a standardized accessory mounting device commonly referred to as a Picatinny, Weaver, or MIL-STD 1913 rail. As used herein, each of these are referred to collectively or interchangeably as a “Picatinny” rail or “standardized” accessory mounting rail, as the differences between these versions is not important to the present invention. 
     A top platform surface  18  extending the complete width of the lug  12  is not required in order to securely mount accessories to a Picatinny rail. In order to reduce the overall weight, it is well known in the art to provide a longitudinal trough or channel  22  along its length. An example of a standard Picatinny rail without a longitudinal channel is shown in the aforementioned Keng Patent Appl. Pub. No. 2008/0092423. An example of a Picatinny rail which includes a longitudinal central channel is shown, for example, in U.S. Pat. No. 6,508,027. 
     According to one aspect of the present invention, longitudinally spaced apart sight elements  24 ,  26  are integrated into the rail  10 . The first sight element  24  includes a visual marker  28  which is positioned substantially centrally of the lateral width of the rail  10 . In preferred form, the first sight element  24  is at or near a forward end region of the rail  10 . The second sight element  26  includes a pair of laterally spaced apart visual markers  30 . Also in preferred form, the second sight element  26  is located at or near an opposite or rearward end region of the rail  10 . 
     In simplest form, the forward or first sight element  24  may comprise a simple upstanding post that is entirely confined within the profile of the forward most lug  12  and laterally centered within the channel  22 . The rearward facing surface  32  may be sufficient to provide a visual marker for the forward sight element  24 , or a spot  28  of contrasting color may be applied or formed thereon. Alternatively, the visual marker spot  28  may include a fiber optic insert or tritium vial to provide enhanced visibility. As can be seen in  FIG. 1 , the forward sight element  24  of this embodiment allows completely unencumbered use of the rail  10  for mounting purposes. 
     Also in simplest form, at the opposite or rearward end of the rail  10  the second sight element  26  may be formed completely within the profile of the rearward most lug  12 . In a simple form, the second sight element  26  may be a substantially centered notch  34  such that visual markers are formed by the remaining structure on either side. Visibility may be enhanced by visual marker spots  30 . These markers  30 , like the forward visual marker  28 , may be a contrasting color or may include a light-gathering fiber optic insert or light-emitting tritium vial. 
     Referring now also to  FIG. 2 , it can be seen that alignment of the visual marker  28  of the forward sight element  24  between visual markers  30  of the rear sight element  26  provides a familiar “post and notch” sight image. 
     The notch  34  between rear sight element  26  visual markers  30  may be of a width similar to that of the longitudinal channel  22 , or may be wider or narrower, as desired. Likewise, the width of the forward element  24  can be equal to the width of the notch  34 , or may be more narrow, if desired. In preferred form, the width of the forward element  24  is no greater than the width of the notch  34 . Providing spaces  36  on each side of the forward element  24  provides a contrasting visual appearance and facilitates quick visual alignment of the forward and rear sight elements  24 ,  26 . However, simply providing a visual marker spot  28  on the rearward face  32  and maintaining the forward most lug uninterrupted along its full width could provide a functional, though less desirable, forward sight element  24 . 
     Referring now to  FIGS. 3 and 4 , therein is shown at  38  a standardized accessory mounting rail with integral back-up sights according to an alternate embodiment. This embodiment illustrates how adjustable forward and rear sight elements  24 ,  26  may be incorporated to allow elevation and windage adjustment. 
     A forward sight element  24  may be made adjustable by using a threaded sight post  40 , like that commonly found in the front sight of an M16 or similar style rifle, for example. An adjustable post  40  includes a threaded portion  42  threadingly received into a socket  44  laterally centered in the longitudinal channel  22 . As is well known, the post  40  may be adjusted in height by incremental rotation. A spring detent  46  is also a well known means for holding the adjustable post  40  in place, while allowing ease of adjustment. The adjustable post  40  may include any of a wide variety of well-known visual markers  28  presented on one or both faces of the post  40 . 
     Longitudinally, the adjustable post  40  may be positioned between opposite side portions of the forward most lug  12 , in a space  14  between adjacent lugs  12 , or a longitudinally enlarged space  48  may be provided. Interruption of the spacing between lugs  12  at the forward most end of the rail  38  is not considered to be a significant detraction from its utility as a standardized mounting rail. In an application where a scope ring or attachment of an accessory is likely to be positioned near the forward end of the rail  38 , the rail  38  may simply be extended as necessary to accommodate placement of the adjustable post  40  of the forward sight element  24 . 
     Referring still to  FIGS. 3 and 4 , a rear sight element  26  that is laterally adjustable for windage or precision aiming adjustment may be provided. In the illustrated embodiment, the rear sight element  26  includes a laterally adjustable member  50  that is mounted to the base  16  by way of one or more set screws  52 . Set screws  52  pass through laterally elongated openings  53  of the member  50  and engage threaded openings  54  in the base  16 . Adjustable member  50  includes a central notch  34  and may include a pair of visual markers  30  on forward and/or rear (not shown) surfaces of the member  50 . By loosening set screws  52 , the member  50 , along with the central notch  34  and visual markers  30 , may be shifted in a lateral direction and then secured in place by tightening the set screws  52 . Alternatively, a lateral dovetail-type engagement (not shown) may be used. 
     The member  50  of the adjustable sight element  26  may be longitudinally positioned in a space  14  between adjacent lugs  12  or may be provided in place of one or more of the lugs  12 . 
     Generally, in order to maximize the sight radius between forward and rear sight elements  24 ,  26 , the elements will be placed at or near opposite ends of the rail  10 ,  38 . In some applications, however, there may be a reason to situate one or both of the sight elements  24 ,  26  such that one or more of the lugs  12  providing functional attachment regions of the rail  10 ,  38  extend beyond the location of the sight element  24 ,  26 . 
     Referring now to  FIGS. 5 and 6 , therein shown at  60  another alternate embodiment of a standardized accessory mounting rail with integrated back-up sights. In this embodiment, the forward and rear sight elements  24 ,  26  include light-gathering enhancements. Here the visual markers  28 ,  30  are end faces of light-gathering fiber optic rods  62 ,  64 . The rods  62 ,  64  may be made in a well-known manner of translucent material. The fiber optic rod  62  of the forward sight element  24  may be of a color contrasting with that of the fiber optic rods  64  of the rear sight element  26 . For example, the front visual marker  28  may be red and rear visual markers  30  may be green. 
     In the illustrated embodiment, the fiber optic rods  62 ,  64  extend longitudinally the span of two transverse lugs  12  and the space  14  there-between. In this embodiment, functionality of the forward most and rearward most slots  14  is lost for purposes of an accessory connection (not shown) passing therethrough. However, the forward and rearward sight elements  24 ,  26  are defined and housed completely within the cross-sectional profile of the attachment lugs  12 . This feature is best seen in  FIG. 9 . The lateral position of the rear fiber optic rods  64  can be in line with or outboard of the central channel  22   
     Also shown in this embodiment  60 , the central longitudinal channel  22  may be formed at a depth greater than that of the transverse slots  14  between lugs  12 . Also, the notch  34  between visual markers  30  of the rear sight element  26 , may be more narrow than that of the longitudinal channel  22 . This differential is not required and may be adjusted as desired to meet the needs of any particular application. 
     Referring now in particular to  FIGS. 8 and 9 , therein is shown a mounting rail  60  like that previously described in  FIGS. 5-7 .  FIG. 8  illustrates the manner in which the sight picture emerges as the rail  60  mounted on a firearm is brought upward into the user&#39;s field of view. When, for example, the forward sight element  24  is situated above the rear sight element  26 , a visual triangle  66  is presented. If the forward sight element  24  is not correctly aligned between the visual markers  30  of the rear sight element  26 , this misalignment will be reflected in the visual triangle  66  as well. 
     As the visual marker  28  of the forward sight element  24  becomes properly aligned both horizontally and vertically between the visual markers  30  of the rear sight element  26 , the sight pattern shown in  FIG. 9  is created. When properly aligned, the forward visual marker  28  is centered between the rear visual markers  30  and a straight horizontal line  68 . 
       FIG. 10  shows an alternate embodiment of a rear sight element  26 . In this example, enlarged laterally-extending openings or channels  70  are formed through the structure supporting the fiber optic rods  64 . In this manner, a greater surface area of the fiber optic rods  64  is exposed to better facilitate their light-gathering ability. Also in this embodiment, the depth of the channel  22  and rear notch  34  are shown to be greater than that of the embodiments shown in  FIGS. 1-4  and lesser than that shown in the embodiment of  FIGS. 5-9 . 
     The supporting members  72  are relatively thin, but in combination provide adequate strength and protection of the fiber optic rods  64  without extending beyond the transverse profile of the mounting lugs  12 . 
     Referring now to  FIGS. 11-14 , therein is shown at  74  another preferred embodiment of the present invention. This embodiment  74  includes light-gathering fiber optic rods  62 ,  64  which function and are mounted like those previously described. Different, however, is that the width of the longitudinal channel  22  is tapered from a more narrow rearward end  76  toward a wider forward end  78 . This tapering of the channel  22 , which does not in any way effect the ability to mount accessories securely to the rail  74 , facilitates the user&#39;s more rapidly acquiring and adjusting a proper sight picture. 
     Best shown in  FIG. 13 , the tapered-width channel  22  allows the user to more quickly find the visual marker  28  of the forward sight element  24  as the rail  74  is brought into the user&#39;s field of view. As the visual markers  28 ,  30  are brought into alignment, the sight picture shown in  14  is presented. The depth of the channel  22  may also be tapered (not shown), if desired. In the embodiment illustrated in  FIGS. 11-14 , the depth of the channel  22  does not vary, but is of a greater depth than the notch  34  of the rear sight element  26 . In this manner, the ability to rapidly acquire and adjust a proper sight picture is enhanced both vertically as well as horizontally. 
     Referring now particularly to  FIGS. 15 and 16 , therein is shown a detail of a fiber optic sight element  62  and mounting structure in longitudinal section. The fiber optic rod  62  is supported by a series of members  75  which may, for example, be substantially aligned laterally and longitudinally with mounting lugs  12 . The rod  62  may be held in place by any known method. In the illustrated example, a substantially cylindrical fiber optic rod  62  is longitudinally inserted through a series of longitudinally aligned bores in the support members  75 . In the illustrated example, the openings of the outer support members  75  are smooth and substantially match the diameter of a selected fiber optic rod  62 . In order to secure the rod  62  without the use of adhesives, the innermost support  76  may be provided with an opening of slightly reduced diameter and shallow threads that grip the outer cylindrical surface of the rod  62 . The diameter  79  of the openings in the outermost support members  75  may be, for example, 0.098 inches. The opening diameter  80  of the innermost support member  76  may be, for example, 0.089 inches and threaded with a #4×40 tap. The fiber optic rod  62  material may be manufactured or pre-cut to the finished length prior to installation. Alternatively, an over-length piece of resin stock may be guided through the support members  75  from an outer end and rotated to allow passage through openings that are sized to be snug. As the rod material reaches the innermost support  76 , its rotation causes it to be lightly gripped by the shallow internal threads  82 , causing it to be firmly held in place. The fiber optic material may be allowed to protrude slightly from the inner end, after which both ends are cut, such as by shearing, to present smooth face surfaces. 
     A substantially identical structure and process may be used for insertion and retention of fiber optic rods  64  of the rear sight element  26 . 
     Referring now to  FIG. 17 , therein is shown an alternate rear sight element  26  in the form of an aperture  84 . The aperture  84  may be round, oval, polygonal, or any desired shape. The aperture  84  provides laterally spaced apart visual markers, defined by an annular edge  86  as well as providing upper and lower visual markers for the rear sight element  26 . If desired, the edge  86  of the aperture  84  maybe provided with a ring  88  of contrasting color or other visual enhancement. 
     As shown in  FIG. 17 , the rear sight element  26  may extend above the top platform  18  level of the mounting lugs  12 , if desired. Such an extension beyond the profile of the Picatinny mounting rail is insignificant and does not inhibit substantially full functionally of the rail, particularly when only affecting one end. 
     The base  16  may have a bottom surface  17  that is flat or slightly concave in the transverse direction, and may include attachment openings  56  through which fasteners can be inserted for securing the rail  38  to, for example, the top of a shot gun receiver. The height  58  of the base  16  may be varied as desired to accommodate any particular application. Alternatively, a rail  10 ,  38 ,  60 ,  74  having integrated sight elements  24 ,  26  of the present invention may be attached to a firearm with a “saddle,” which attaches to sides of the receiver or formed as part of another accessory device, such as a shotshell carrier, or the rails of barrel shroud at the 9-, 12-, or 3-o&#39;clock (or intermediate angle) positions. 
     As used herein, “forward” or “front” refers to the muzzle or discharge end or direction of a firearm, distal from the user. “Rearward” or “rear” refers to end of the firearm proximal to the user and opposite the direction of a projectile discharge. 
     As used herein, “firearm” is intended to include a shotgun, rifle, handgun, air gun, airsoft, paintball marker, crossbow, bow, or any other device requiring sighting for aiming the discharge or launch of a projectile of any type. 
     As used herein, “tritium vial” means a sight marker insert of the type in which a thin glass vials whose inner surface are coated with a phosphor material is filled with tritium gas to produce fluorescent light by radioluminescence. 
     The illustrated embodiment was chosen and described to provide the best disclosure of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by any allowed claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled. The drawings and preferred embodiments do not and are not intended to limit the ordinary meaning of the claims and their fair and broad interpretation in any way.