Abstract:
The present invention comprises a new and improved adjustable rear sight for firearms which comprises a polymer sight body and a metal aperture screw which is adjustable for elevation by screwing the aperture screw up or down in a threaded insert which is inserted in a cavity which extends from an upper surface to a lower surface of the sight body. The polymer sight is held securely in a sight mounting dovetail via a flex plate which is held to the bottom of the sight body by a flange on the bottom end of the threaded insert. The flex plate is sized to fit tightly in the sight mounting dovetail.

Description:
This application claims benefit of Provisional 60/446,896 filed Feb. 12, 2003. 

   FIELD OF THE INVENTION 
   In general, the present invention relates to firearms. More particularly, the present invention relates to an improved adjustable rear sight for firearms. 
   DESCRIPTION OF THE PRIOR ART 
   All firearms are equipped with some sort of sighting system to assist the shooter in aiming the weapon. There are many different sighting systems including telescopic sights, holographic sights, red dot sights, and iron sights. The term “iron sight” does not refer to the material the sight is made of but instead refers to a category of sights that consist of a rear sight located on or near the rear end of the gun closest to the shooter and a front sight located near the end of the barrel of the gun opposite the shooter. “Iron sights” may be constructed of iron, steel, aluminum, polymer or any other material of sufficient strength, rigidity and durability. The term polymer is well known to those skilled in the prior art and conveys and defines a specific class of materials when used with respect to firearms, firearm parts or accessories. The rear sight generally consists of a fixture attached to the gun that contains an aperture or a notch and the front sight generally consists of a vertical blade or post located near the end of the barrel. The shooter looks through the notch or aperture of the rear sight and centers the front sight in it. The gun is aimed by placing the front sight over the target while it is centered in the notch or aperture of the rear sight. Iron sights of both the notch and aperture variety are well known to those skilled in the prior art. Additionally, iron sights may be of the fixed or adjustable variety. 
   A fixed rear sight is generally constructed out of a single piece of metal plastic or polymer material. The height of the front sight must be exactly matched to the height of the rear sight in order to produce a sight picture that is the same elevation as the point of impact of the bullet. The elevation on fixed sights is set at the factory and generally can only be adjusted by exchanging the front sight for one of a different height or by filing the front sight to lower its height. Horizontal adjustments are made on fixed sights by “drifting” the sight to the left or right in its mounting dovetail. These adjustments must often be made by a skilled gunsmith. Adjustable sights are designed to allow the shooter to adjust the sight vertically and/or horizontally to bring the point of impact of the bullet in line with the sight picture on the target. Variations in ammunition, distance to the target, barrel length and other factors cause the point of impact of the bullet to shift. Adjustable sights allow the shooter to easily compensate for these variations. Sight adjustment is achieved through a variety of means from adjustment screws, to spring loaded clips, to simply sliding or “drifting” the base of the sight horizontally in a mounting dovetail. 
   In general, fixed sights by virtue of their simplicity tend to be more durable and less expensive than adjustable sights, which are rather complicated to manufacture and tend to be rather fragile. For those reasons, handgun manufacturers commonly utilize fixed sights for handguns intended for defensive use. One drawback of fixed sights is that the height of the front and rear sight must be matched to the particular handgun. Manufacturers who make models of the same handgun with multiple barrel length or in multiple calibers must produce or purchase a different height sight for each model of handgun they produce. This adds expense to the manufacturing process due to the need to produce additional tooling or to purchase and stock additional parts. Additionally, because ammunition used by the particular shooter may vary in velocity or bullet weight, the sights must often be adjusted by the shooter to match the ammunition used. 
   Thus, there is a need for an improved adjustable rear sight with improved durability, which is less complex and expensive to manufacture and assemble. 
   SUMMARY OF THE INVENTION 
   In view of the above described disadvantages inherent in the iron sights of the prior art, the improved adjustable rear firearm sight of the present invention not only allows vertical sight adjustment, but is also inherently more durable and less expensive to manufacture and assemble than other adjustable sights, due to its simplicity of design. As such, the general purpose of the present invention, which will be described subsequently in greater detail, is to provide a new and improved adjustable rear sight for a handgun or a rifle which has all of the advantages of the prior art and none of the disadvantages. 
   To attain this purpose, the present invention essentially comprises a sight body which is molded, formed or machined from a rigid polymer type material, or any other material of sufficient strength and rigidity, including but not limited to steel, aluminum, carbon fiber or any other like material. Inside this fixed sight body is a threaded insert into which a threaded aperture screw is installed. A sight notch is cut into the head of the aperture screw and the elevation of the aperture is adjusted by rotating the aperture screw in the threaded insert to raise or lower the height of the sight notch. In addition to a notch, the aperture could be a peep or ghostring type aperture, both of which are well known to those skilled in the prior art. Each 180 degree turn of the aperture screw raises the point of impact of the bullet an equal distance. The aperture screw adjustment is locked by spring clips which click into notches cut into the side of the aperture screw head. These notches stop the screw on every 180 degree turn and assure that the sight notch is in line with the barrel of the gun. It is also contemplated that the adjustment could be achieved via a spring loaded plunger which clicks into detents cut in the base of the aperture screw. The sight is attached to the firearm via a dovetail cut into the barrel or receiver of the firearm which receives compression washers which are placed between a flange on the threaded insert and the polymer sight body. The compression washers on the threaded insert eliminate the expense of molding a metal insert into the polymer insert to attach it to the dovetail in the gun. In addition to compression washers, other means of attachment are contemplated such as, but not limited to, a flex plate, a dovetail machined from a steel sight body, enlarging the flange on the threaded insert to fit tightly in the dovetail on the firearm, or mounting the sight to the firearm with screws. 
   There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
   In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in this application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
   Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. 
   Therefore, an object of the present invention to provide a new and improved adjustable rear sight for a handgun or a rifle which is less costly and more efficient to manufacture than the adjustable rear sights of the prior art. 
   It is a further object of the present invention to provide a new and improved adjustable rear sight for a handgun or a rifle that is inherently more rugged and durable. 
   An even further object of the present invention is to provide a new and improved adjustable rear sight for a handgun or a rifle which is less costly to assemble into the finished product. 
   Still another object of the present invention is to provide a new and improved adjustable rear sight for a handgun or a rifle, which reduces the number of parts, which a manufacturer must produce. 
   An even further object of the present invention is to provide a new and improved adjustable rear sight for a handgun or a rifle with simplified operation and fewer parts than the prior art. 
   These, together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages, and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated preferred embodiments of the invention 

   
     BRIEF DESCRIPTION OF THE PICTORIAL ILLUSTRATIONS AND DRAWINGS 
       FIG. 1  Exploded view of the improved adjustable rear sight of the present invention. 
       FIG. 2  Top view of the improved adjustable rear sight of the present invention. 
       FIG. 3  Front view of the improved adjustable rear sight of the present invention. 
       FIG. 4  Side view of the improved adjustable rear sight of the present invention. 
       FIG. 5  Bottom view of the improved adjustable rear sight of the present invention. 
       FIG. 6  Side view of the spring clip of the improved adjustable rear sight of the present invention. 
       FIG. 7  Top view of the aperture screw of the improved adjustable rear sight of the present invention. 
       FIG. 8  Side view of the aperture screw of the improved adjustable rear sight of the present invention. 
       FIG. 9  Alternative side view of the aperture screw of the improved adjustable rear sight of the present invention. 
       FIG. 10  Top view of the flex plate of the improved adjustable rear sight of the present invention. 
       FIG. 11  Side view of the flex plate in relation to the threaded insert and a mounting dovetail. 
       FIG. 12  Alternate side view of the flex plate of the improved adjustable rear sight of the present invention. 
       FIG. 13  A top view of an alternate embodiment of the present invention showing a sight body with a plunger cavity. 
       FIG. 14 . A bottom view of an alternate embodiment of the present invention showing the bottom surface a sight body with a plunger cavity. 
       FIG. 15  A cut away view of an alternate embodiment of the present invention showing a sight body with a plunger cavity and with a spring and plunger interfacing with the aperture screw. 
       FIG. 16  A top view of an aperture screw with a plunger notch. 
       FIG. 17  A bottom view of an aperture screw with a plunger notch. 
       FIG. 18  A side view of an aperture screw with a plunger notch. 
       FIG. 19  An alternate side view of an aperture screw with a plunger notch. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to  FIGS. 1 and 4 , a sight  10  is comprised of a sight body  30 , an aperture screw  70  and a threaded insert  100 . The sight body  30  is attached to a dovetail  116  cut into a firearm (not shown). The sight body  30  is formed from a material such as, but not limited to, polymer, carbon fiber, steel, aluminum, or any other material of like strength and rigidity. The sight body  30  has an upper surface  32 , a lower surface  34 , a first end  36 , a second end  38 , and a center cavity  40 . Protruding above the upper surface  32  is a rim  46  that is open across the second end  38  and extends around the edge of the upper surface  32  of the sight body  30  as shown in  FIG. 2 . A sight opening  48  is cut into the rim  46  on the first end  36  of the sight body  30  at a position that is in line with the bore of the firearm (not shown). A spring clip recess  50  is cut on opposite sides of the rim  46  located 90 degrees from the sight opening  48 . The spring clip recess  50  receives a spring clip  56 . 
   The center cavity  40  extends from the upper surface  32  through the sight body  30  to the lower surface  34  as shown in  FIG. 1 . Cut into the upper surface  32  forming a radius around the center cavity  40  is an aperture screw cavity  58  as seen in  FIG. 2 . Cut into the lower surface  34  is a male dovetail  52 . Also cut into the lower surface  34  is a flange cavity  54  shown in  FIG. 5 . The flange cavity  54  is circular cut around the center cavity  40 . The flange cavity  54  is cut to a diameter great enough that the radius of the cavity extends sight body  30  creating an opening in the male dovetail  52  at each end. Referring now to  FIG. 1 , the threaded insert  100  is inserted into the center cavity  40  of the sight body  30  from the lower surface  34 . The threaded insert  100 , comprises a cylinder  102 , and a flange  104 . The cylinder  102  has a threaded inner surface  106 . As seen in  FIGS. 1 and 4 , two flex washers  108  are deposited over the flange  104  although it is contemplated that a single compression or flex washer  108  may be utilized. The flange  104  and the flex washers  108  fit in the flange cavity  54  on the sight body  30  when the threaded insert  100  is fully inserted in the cavity  40  of the sight body  30 . The flex washers  108  extend slightly beyond the male dovetail  52 . The aperture screw  70  shown in FIGS.  1  and  7 – 9 , screws down through the threaded inner surface  106  of the threaded insert  100  from the upper surface  32  of the sight body  30 . The aperture screw  70  is comprised of a top end  72  and a bottom end  74  and a threaded shank  78 . The aperture screw  70  has a head  76  formed on the top end  72  of the aperture screw  70 . The head  76  has a first flat surface  86 , a second flat surface  88 , a first radius  90 , and a second radius  92 . The first flat surface  86  and second flat surface  88  have scallops  91  cut into them which leaves a sight plane  89  which consists of a flat surface on the top end  72  of the aperture screw  70  that extends from the first radius  90  to the second radius  92 . An aperture notch  82  is cut into the center of the sight plane  89  and spring click notches  80  are cut into the head  76  of the aperture screw  70  at opposite ends of the sight plane  89 . Referring now to  FIG. 4 , the assembled sight  10  is mounted in the female dovetail  116  of the firearm (not shown). The flex washers  108  extend slightly beyond the male dovetail  52  and, as the sight  10  is pushed into the female dovetail  116  of the firearm (not shown), the flex washers  108  compress slightly and bias the sight  10  upwards in the female dovetail  116 . This upwards biasing of the sight  10  provides sufficient friction to hold the sight  10  securely in the female dovetail  116  and ensure that it is securely mounted on the firearm (not shown). Horizontal adjustment of the sight  10  is accomplished by sliding the sight  10  laterally in the female dovetail  116  to move the point of impact of the bullet (not shown) to the left or right of the shooter. Vertical adjustment of the sight  10  is accomplished by rotating the aperture screw  70  in the threaded insert  100 . Each ½ turn of the aperture screw  70  raises or lowers the point of impact of the bullet (not shown) by an equal distance. The spring clips  56  clicking in the spring click notches  80  on each half turn of the aperture screw  70  accomplish alignment of the aperture screw  70  at the proper position. Additionally, the aperture screw  70  may have a tritium cavity  84  into which is placed a tritium filled glass tube (not shown) to provide illumination of the sight  70  for use at night or in low light conditions. The use of tritium to illuminate weapon sights in low light or darkness is well known to those skilled in the prior art. 
   An alternative embodiment of the present invention shown in  FIGS. 10–12  is a flex plate  110  which may be utilized in place of the flex washers  108  as described above. The flex plate  110  is generally comprised of a stamped piece of steel or other suitable material. It has an opening  112  which fits over the cylinder  102  of the threaded insert  100  and a dovetail shoulder  114  which is dimensioned to be slightly larger than the dovetail  116 . When the sight  10  is inserted into the female dovetail  116 , the dovetail shoulder  114  presses against the sides of the female dovetail  116  and forces the flex plate  110  to flex upwards and bias the sight  10  in the female dovetail  116  and securely attach the sight  10  to the firearm (not shown). (Shown in  FIG. 11  is a drawing of the flex plate  110  and the threaded insert  100  shown in relation to the female dovetail  116 .) 
   Another alternative embodiment of the present invention (not shown) is the sight body  30  that is machined out of steel, aluminum, or any other suitable metal. In this embodiment the threaded insert  100 , flex washers  108 , and/or flex plate  110  could be eliminated and the cavity  40  could be threaded to receive the aperture screw  70 . Attachment of the sight  10  to the firearm (not shown) would be accomplished via a traditional dovetail (which is well known to those skilled in the prior art) cut into the lower surface  34  of the sight body  30  of the sight  10  as illustrated in  FIG. 4 . 
   Yet another alternative embodiment of the present invention (not shown) is the threaded insert  100  which has a flange  104  which is dimensioned so that it would press against the dovetail  116  and thus eliminate the need for the use of flex washers  108  or the flex plate  110  to secure the sight  10  to the firearm (not shown). 
   Still another alternative embodiment of the present invention (not shown) is the sight  10  an employs the aperture screw  70  which has a peep sight or ghost ring sight (both which are well known to those who are skilled in the prior art) instead of the aperture notch  82  which was disclosed above. 
   Yet another embodiment of the present invention shown in  FIGS. 13–19 , the sight  10  utilizes a plunger  56   a  and a spring  57   a  in lieu of the spring clip  56  to provide for click stops for the vertical adjustments of an aperture screw  70   a . The plunger  56   a  and spring  57   a  are inserted into a plunger cavity  55   a  which is drilled or cut into the lateral side of a center cavity  40   a  of a sight body  30   a . The plunger cavity  40   a  extends from a lower surface  34   a  of the sight body  30   a  to an upper surface  32   a  of the sight body  30   a  as shown in  FIG. 13 . The aperture screw  70   a  has a plunger notch  80   a  cut into the base of the aperture screw  70   a  at opposite ends of a sight plane  89   a . As the aperture screw  70   a  is turned the plunger  56   a  is biased upwards against the aperture screw  70   a  and clicks into the plunger notches  80   a  providing click stops for the vertical adjustments of the aperture screw  70   a.    
   Changes may be made in the combination, operations, and arrangements of various parts and elements described herein without departing from the spirit and scope of the invention. 
   
     
       
             
           
             
             
             
             
           
         
             
                 
             
             
               Parts List 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
               10 - 
               Sight 
                88 - 
               Second Flat Surface 
             
             
               30 - 
               Sight Body 
                89 - 
               Sight Plane 
             
             
               32 - 
               Upper Surface 
                90 - 
               First Radius 
             
             
               34 - 
               Lower Surface 
                91 - 
               Scallops 
             
             
               36 - 
               First End 
                92 - 
               Second Radius 
             
             
               38 - 
               Second End 
               100 - 
               Threaded Insert 
             
             
               40 - 
               Center Cavity 
               102 - 
               Cylinder 
             
             
               46 - 
               Rim 
               104 - 
               Flange 
             
             
               48 - 
               Sight Opening 
               106 - 
               Threaded Inner Surface 
             
             
               50 - 
               Spring Clip Recess 
               108 - 
               Flex Washers 
             
             
               52 - 
               Male Dovetail 
               110 - 
               Flex Plate 
             
             
               54 - 
               Flange Cavity 
               112 - 
               Opening 
             
             
               56 - 
               Spring Clip 
               114 - 
               Dovetail Shoulder 
             
             
               70 - 
               Aperture Screw 
               116 - 
               Female Dovetail 
             
             
               72 - 
               Top End 
                30a - 
               Sight Body 
             
             
               74 - 
               Bottom End 
                32a - 
               Upper Surface 
             
             
               76 - 
               Head 
                34a - 
               Lower Surface 
             
             
               78 - 
               Threaded Shank 
                40a - 
               Center Cavity 
             
             
               80 - 
               Spring Click Notch 
                55a - 
               Plunger Cavity 
             
             
               82 - 
               Aperture Notch 
                56a - 
               Plunger 
             
             
               84 - 
               Tritium Cavity 
                57a - 
               Spring 
             
             
               86 - 
               First Flat Surface 
                70a - 
               Aperture Screw 
             
             
                 
                 
                80a - 
               Plunger Notch 
             
             
                 
                 
                89a - 
               Sight Plane