Abstract:
A cap for a receiving rail of a firearm and methods of operating the same are disclosed. An illustrated cap includes a resiliently deformable plate. The example cap also includes engaging members on the opposite sides of the center of the plate where the plate is curved such that the engaging members approach each other when the cap is unloaded.

Description:
RELATED APPLICATION  
       [0001]     This patent is a continuation of International Patent Application Serial No. PCT/EP2004/001329, which was filed on Feb. 12, 2004, which is hereby incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE  
       [0002]     This disclosure relates generally to firearms, and, more particularly to caps for receiving rails of firearms, wherein opposite sides of the caps have elongated engaging rails.  
       BACKGROUND  
       [0003]     Conventional small firearms, e.g. handguns, are equipped with one or more receiving rails, upon which accessories (e.g. telescopic sights, laser target devices, floodlights, night target devices, etc.) can be mounted. Some receiving rails are diamond shaped in cross-section such that an accessory with depending arms may dovetail around and grip the rail. In many case, the accessories must be readjusted each time they are mounted. Generally, these known receiving rails and their rear parts (which may also have transverse slots) are uncovered, which can make handling of the weapon difficult or awkward for the marksmen.  
         [0004]     Conventional weapons have tried to avoid the difficulty and awkwardness of handling such firearms by implementing covers or caps for the corresponding receiving rail. These known caps slide onto the receiving rail from the front, and are locked by spring mechanisms. The caps cover the unused portion of the receiving rail. These known caps are constructed as flat covering caps with engaging rails constructed on both sides. These engaging rails of the cap can be slipped under the borders of the dovetail construction of a receiving rail to secure the cap in place.  
         [0005]     The use of such a cap solves the handling problems noted above, but other disadvantages with these conventional caps remain. For example, any accessory that is mounted on the front part of a receiving rail must be removed before such a prior art cap can be slipped onto the rear part of the receiving rail.  
         [0006]     An example of a conventional cap that slides onto the receiving rail is known from U.S. Pat. No. 5,826,363. However, this known cap is very complex and rigid and cannot be deformed in a resilient manner.  
         [0007]     A sight cap made of sheet metal is already known from German patent DE 299 535. This sight cap snaps into two longitudinal slots of the receiving rail on opposite sides of the sight. However, this cap does not sit tightly on the sight under tension, but rather must be removed by lifting the sight bracket up. Therefore, this cap is poorly suited as a cover for a receiving rail.  
         [0008]     A cover is also known from German patent document DE 90 02 289.4 U1. This known cover can be placed over the telescopic sight, breech and trigger and held in place by Velcro® strips. This cover is not at all suitable for a receiving rail. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0009]      FIG. 1  is a perspective view of an example firearm with an example cap on an example receiving rail.  
         [0010]      FIG. 2  is a cross-sectional view of the example cap of  FIG. 1  mounted on the example receiving rail.  
         [0011]      FIG. 3  is an enlarged cross-sectional view of the example cap of  FIG. 1 . 
     
    
     DETAILED DESCRIPTION  
       [0012]     Throughout this patent, position designations such as “above,” “below,” “top” “forward,” “rear,” etc. are referenced to a firearm held in a normal firing position (i.e., pointed away from the shooter in a generally horizontal direction).  
         [0013]      FIG. 1  shows an example firearm  1  with an example rail  3  on which an example cap  11  is mounted. Though the firearm  1  shown in  FIG. 1  is a rifle, the cap  11  may be used with any type of firearm and with any type of receiving rail  3 . The cap  11  comprises a plastic plate  13 , which is slightly curved in an unloaded or unstressed state. The plate  13  has an inner surface  17  and an outer surface  19 . The median axis  23  of the curvature is vertical on the drawing plane of  FIGS. 2 and 3 .  
         [0014]     The inner surface  17  of the plate  13  has engaging rails  15 . The rails  15  are on opposite side of an equidistant from the median axis  23 . The rails  15  run longitudinally into and/or out of the drawing page and are parallel to one another. Each of the engaging rails  15  has a protruding strip  21  on its free end located at a distance from the inner surface  17  of the plate  13 . The protruding strips  21  of the engaging rails  15  face one another. They are arranged and constructed in such a way that they can engage opposite lateral edges of a receiving rail (not shown), which is mounted to a weapon (not shown). The lateral edges grip the receiving rail in a dovetailed manner. That is, the protruding strips  21  and the engaging rails  15  interlock with corresponding edges of the receiving rail so that a dovetail joint is formed between the cap  11  and the receiving rail.  
         [0015]     A projection  25  is constructed adjacent one of the engaging rails  15 , the length of this projection  25  corresponds to the width of a lateral slot (not shown) in the receiving rail. The projection  25  is used to guide the cap  11  into the correct position to be connected properly with the receiving rail. The mechanics of this mounting process are discussed in greater detail below.  
         [0016]     The example cap  11  is mounted to a receiving rail in the following manner. First one of the two engaging rails  15  is hooked laterally over a lateral edge of a receiving rail. It is advantageous to use the engaging rail  15  adjacent to the projection  25  as the first to be hooked over the edge of the receiving rail because the projection  25  is guided into a lateral slot of the receiving rail. This ensures the cap  11  will make a proper and secure connection with the receiving rail. The entire length of the protruding strip  21  engages the protruding lateral edge of the receiving rail.  
         [0017]     Next, the cap  11  is bent around the median axis  23  over the even construction of the plate  13  in the direction of the arrows so that the plate  13  is curved in a manner opposite that shown in the drawing. The plate  13  is flexible and can resiliently curve in this manner without damage and with the ability to reassume its former shape. The bending causes the distance between the protruding strips  21  to enlarge and slightly exceed the distance between the lateral edges of the receiving rail. With the enlarged length, the cap  11  is stretched so that the other engaging rail  15  (e.g., the one without the projection  25 ) and corresponding protruding strip  21  can clear the associated lateral edge of the receiving rail.  
         [0018]     As the plate  13  is released, it bends back slightly against the direction of the arrows, until the protruding strips  21  fully engage respective ones of the two opposite lateral edges of the receiving rail and thereby bring the plate  13  up against the surface of the receiving rail. The plate  13  is resilient and tries to maintain its shape. Therefore, the plate  13  provides a contact pressure against and under the receiving rail to maintain the connection of the protruding strips  21  and engaging rails  15  with the corresponding lateral edges of the receiving rail. Also, because the projection  25  engages in a transverse slot of the receiving rail, it prevents the cap  11  from slipping in the longitudinal direction of the receiving rail. As a result of the continuous tension caused by the resilient cap, the cap  11  sits firmly on the receiving rail, without shaking or rattling.  
         [0019]     The removal of the cap  111  occurs in the reverse order of the previously described actions, namely, by bending the plate  13  first in the direction of the arrow and then simply removing it from the receiving rail in a peeling off type of action.  
         [0020]     A person of ordinary skill in the art will appreciate that the outer surface  19  of the plate  13  can have ribs  30  and/or other constructions to increase the rigidity of the cap  11 . When used, these structures should be constructed to not hamper the resilient bending of the cap  11  in the direction of the arrow.  
         [0021]     A person of ordinary skill in the art will further appreciate that the illustrated example cap  11  is made from plastic that is not too hard, and remains resilient. As a result, the plastic cap  11  does not scratch or damage the receiving rail, but rather protects it from damages.  
         [0022]     The example construction shown in the drawing is only an example. Other constructions are also possible. For example, the plate  13  can be laterally shortened by the part(s) exceeding the engaging rails  15 .  
         [0023]     A person of ordinary skill in the art will further appreciate that the example cap  11  illustrated herein is an improvement over conventional caps because it is a simpler device that avoids the aforementioned problems of the prior art. The illustrated example cap  11  is deformable in a resilient manner. Thus, the cap  11  does not have to be slipped onto the receiving rail from the front (or from the rear), as required by the prior art, but, rather, can be simply clipped or snapped onto the receiving rail at a right angle. Also, the two engaging rails  15  approach each other in the unloaded or unstressed state because the plate  13  strives to maintain its shape as shown in the figure. By maintaining its shape, the plate  13  and the engaging rails  15  fit tightly over the receiving rail.  
         [0024]     A person of ordinary skill in the art will further appreciate that, if the example cap  11  is used with a receiving rail, upon whose front part a targeting mechanism or other accessory is mounted, then the accessory does not have to be removed to add the cap  11  to the receiving rail. Rather the cap  11  can simply be pressed onto the available free part of the receiving rail and will, thus, be reliably seated there. Also, the cap  11  can be removed from the receiving rail without removing the accessory. To this end, the engaging rail  15  is bent outward, and the cap  11  is then released and removed from the receiving rail and can be removed.  
         [0025]     One advantage of the illustrated example is the inclusion of a projection  25  on the inner surface  17  of the plate  13 . The projection  25  is designed for engagement in a counter construction in or on the receiving rail. When the cap  11  is snapped onto the receiving rail, the projection  25  engages the counter construction and prevents the cap  11  from slipping in a longitudinal direction along the receiving rail, even when there is no targeting mechanism or other accessory attached to block such movement.  
         [0026]     In the illustrated example, the projection  25  is constructed as a protuberance of an engaging rail  15 . This improvement is designed for receiving rails which have transverse slots for the attachment of accessories, as most receiving rails now do.  
         [0027]     The cap  11  may have a simple, square surface. However, it is preferable that its corners be rounded off. Rounding the corners reduces the danger of the marksman accidentally removing the cap  11  from the receiving rail by, for example, catching his sleeve on the cap  11  and pulling it off of the receiving rail.  
         [0028]     In a preferred example, the cap  11  is formed from a single piece of plastic. There are many benefits to the illustrated example plastic cap  11 . For instance, it can be manufactured economically and easily. It is light. It does not oxidize, and it does not damage the surface of the receiving rail. Moreover, the plastic cap  11  has the advantage that it can, if necessary, be easily shortened by, for example, cutting the cap with a sharp instrument such scissors. Markings can be made on the cap  11  to facilitate such shortening. Such markings can be positioned to not be visible when the cap  11  is fitted to the rail.  
         [0029]     The cap  11  of the illustrated example can also be manufactured in variable lengths to adapt to the different accessories that can be mounted onto the receiving rail. Alternatively, or additionally, short, uniform caps  11  can be manufactured, which can then be snapped onto the sections of the receiving rail to be covered. The short caps  11  are placed in whatever position and amount are necessary to cover the receiving rail.  
         [0030]     A person of ordinary skill in the art will appreciate that the engaging rails  15  do not have to be continuous. It is sufficient if individual projections are provided in place of a continuous rail. Such individual projections will ensure the secure seat of the cap  11  on the receiving rail.  
         [0031]     Although certain example methods, apparatus and articles of manufacture have been described herein, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.