Dual-zero sight for a firearm

[0001] This application is a continuation-in-part, and claims priority, of patent application Ser. No. 10/772,154, filed Feb. 3, 2004, entitled “Dual-Zero Sight For A Firearm,” and issued Nov. 29, 2005 as U.S. Pat. No. 6,968,643, which claims priority of Provisional Application Ser. No. 60/445,173, filed Feb. 3, 2003, entitled “Dual-Zero Sight”, which is hereby incorporated by reference.

[0002] 1. Field of the Invention

[0003] This invention relates, in general, to gun sights for shotguns and other firearms. More specifically, this invention relates to an adjustable sighting system that may be used for sighting-in a plurality of shooting tasks, for example, shooting with different ammunition, such as long range and close range ammunition.

[0004] 2. Related Art

[0005] For hunters, sportsmen, law enforcement personnel and other gun users, it is difficult or impractical to carry several firearms in the field. However, the type of ammunition used is often changed in response to the demands of different situations, for example, the change from large to small game. Consequently, a number of smoothbore firearms, and their ammunition, have been modified to improve their effectiveness over a range of shooting tasks. One such modification permits the firing of a plurality of ammunition from the same gun, for example, single-slug and buckshot loads. Typically, single-slug loads are used for long range targets, and buckshot loads are used for short range targets. Due to the substantially different ballistic characteristics of these loads, “zeroing-in” or “sighting-in” targets with these different loads using a single sight can be problematic.

[0006] Several attempts have been made to provide a shotgun sight that is capable of accurately sighting-in shots taken with both slug and buckshot loads. For example, U.S. Pat. No. 2,781,583 (Grumble) describes a gun sight attachment, which converts the typical bead sight of a shotgun to a blade sight, such as may be found on a rifle. The blade sight attachment slides over the tip of the barrel and surrounds the bead sight and barrel tip.

[0007] U.S. Pat. No. 3,193,932 (Johnson) discloses a detachable front sight that may be used to assist in the sighting of a gun when firing different ammunition. This sight extends vertically above the gun barrel at its tip and replaces the normal bead sight. Screws are threaded through the generally flat upper surface of the sight and into the barrel to hold it in place.

[0008] U.S. Pat. No. 3,975,851 (Bedford) teaches another detachable sight for use with shotguns that helps users align slug-load shots with a target. This sight comprises a rear-mounted apparatus featuring a V-shaped notch through which the front sight, typically a bead sight, may be viewed. In one embodiment of this design, adjustments for windage and elevation may be made.

[0009] Some firearms of the late 1800's and early 1900's included a rear sight device featuring range adjustability for a single ammunition. A Model 1898 U.S. Magazine Rifle includes a sighting device having an elongated “leaf” with indicia to provide a calibration reference for range. The eye piece of this sighting device is raised or lowered to achieve increased shooting accuracy at a desired range, by means of a slide that is moved along the leaf to the appropriate indicia. Still, this 1898 sighting device has a single rear sight, that is, a single “zero.” This 1898 device has one elevation adjustment and one windage adjustment. It is adapted for use with a single firearm shooting a single ammunition over a range reportedly from about 200–2000 yards. Such a sight is understandable in view of the state of the art in such firearms of that era, wherein the military firearm and ammunition may have produced a trajectory that required substantial adjustments in aiming, especially in elevation, depending on distance of the target from the user of the firearm.

[0010] Another firearm of the late 1800's included a rear sighting device featuring range adjustability for a single ammunition. A Model 1899 military rifle includes a rear sighting device with a pivotal arm. The pivotal arm carries a single member that has two outer surfaces that may each be used as a sight. Pivoting the arm serves to place one or the other of the outer surfaces in a position for use as the rear sight. The 1899 sighting device does not have two separate sighting members and does not have separate elevation adjustment for a plurality of sights and does not have separate windage adjustment for a plurality of sights. Again, such a sight is understandable in view of the state of the art in such firearms of that era, for making substantial adjustments in elevation.

[0011] Still, there remains a need for a sight system that may be used to accurately sight-in or “zero” shots with various ammunition (such as slugs or buckshot), or for varying shooting tasks as desired. There still remains a need for such a sigh system that does not require significant or difficult adjustments to the firearm in the field to switch sights for different ammunition.

[0012] The invention comprises a sighting device for a firearm that has a plurality of separate sights adaptable for “zeroing” the same gun with different ammunition. This multiple-zero sighting system comprises separate windage and elevation adjustments for each sight, so that ammunition having different trajectories may be fired accurately from a single firearm. Preferably, the separate sights may be linked such that moving one component into the sight path automatically removes the other from the line of vision. The plurality of sights may be simply interchanged by rotating, flipping, or sliding the unnecessary element/component out of the sight path. The plurality of sights may be mounted to an arm that pivots between one or more raised positions and one or more lowered positions, which pivoting may serve to select the operable sight and/or to adjust elevation of that sight.

[0013] The invention may comprise using the multiple-zero sighting device as the rear sight on the firearm, preferably in combination with a front sight. The front sight preferably comprises a blade, post, or fin mounted at the distal end of the gun barrel generally on top of a bead sight. The height of the blade, post, or fin optionally may be adjustable in elevation by raising or lowering the blade, post, or fin or by removing it altogether.

[0014] Preferably, windage and elevation adjustments for each of the multiple zero systems are provided on the same sight unit, such as the rear sight unit. This way, there are separate windage and elevation adjustments for each of the zero systems, but they are close to each other, for example, near the rear/proximal region of the firearm on a single sight unit. Such a rear/proximal adjustment system may be used in combination with a front/distal blade, post, or fin, as discussed above, which optionally may be adjustable in elevation. Thus, for embodiments with two zero systems, two windage adjustments are provided on the rear sight unit and two elevation adjustments are provided on the rear sight unit, and the front sight optionally may also be adjustable in elevation. In such embodiments, which have multiple windage and multiple elevation adjustments on a single sight unit, one adjustment may effect the other, for example, in the case of the preferred windage adjustments, a carriage may be transversely moveable on the firearm as means for the first windage adjustment, and a sub-unit on the carriage may be transversely moveable on said carriage as means for the second windage adjustment. Still, the two windage adjustments of these embodiments may be considered “separate” because one is designated for each zero system.

[0015] Alternatively, the separate windage and elevation adjustments for multiple zero systems may be provided on different sight units. For example, windage and elevation adjustments for one of the zeros (for example, the zero system for long range ammunition) may be provided on the rear/proximal sight unit, while windage and elevation adjustment for the other of the zeros (for example, the zero system for short range ammunition) may be provided on a front/distal sight unit. This way, there are separate windage and elevation adjustments for each of the zero systems, but they are distanced from each other, nearer the front and nearer the rear of the firearm on two sight units.

[0044] Referring to the Figures, there are shown several, but not the only, embodiments of the invented multiple-zero sight system. Windage and elevation adjustments are provided for each of the multiple zeros, and may be accomplished by various means. While the windage adjustments and/or the elevation adjustments may effect each other, an important feature of the preferred embodiments is that each of the multiple zeros may be “pre-zeroed” in a manner whereby the user can later switch back and forth between the zeros (for example, during shooting) without re-zeroing the apparatus. “Switching back and forth” preferably is done by flipping, pivoting, or otherwise moving an arm or other member that holds at least two sight elements, so that the two sight elements are alternatively moved into and out of the line of sight.

[0045] Windage adjustment for the multiple-zero sighting device(s) may be accomplished by moving a pivot arm or other moveable member transversely relative to the longitudinal axis of the firearm and/or may be accomplished by moving the sight element(s) transversely relative to the pivot arm. Elevation adjustment may be accomplished by pivoting a pivot arm or other moveable member to varying angles relative to the firearm and/or by moving the sight element(s) longitudinally on the pivot arm. Preferably, these sight-alignment calibrations are performed once, prior to entering the field, thereby eliminating the need for complex in-the-field adjustments when switching between ammunition types and sight components.

[0046] In one rear sight unit embodiment, the two independently adjustable sighting components are a hollow ghost ring and a V-shaped notch. See FIGS. 1–6. The rear sighting elements/components are generally used in combination with an elevation-adjustable front sight to align a shot. Such systems may include a total of two windage adjustments (both on the rear sight) and three elevation adjustments (two on the rear sight and one on the front sight). Typically, the hollow ghost ring is used to align shots taken with buckshot and the V-shaped notch is used for slug loads. The plurality of sight elements may be simply interchanged by rotating, flipping, or sliding the unnecessary element out of the sight path, for example, in this embodiment, the ghost ring and V-shaped notch are arranged approximately perpendicular to one another upon an “L” shaped frame. The ghost ring may be mounted to the stem of the “L” and the V-shaped notch to the base of the “L”, or vice versa. The “L” shaped frame preferably pivots about its elbow such that either the stem or base, and the corresponding sighting element, is extending vertically from the pivot point and positioned within the sight path. This way, the switch between rear sight elements/components is made by pivoting one sighting element out of the sight path and the other into the path. Preferably, each of the rear sight elements/components, ghost ring and V-shaped notch, include separate adjustments for windage and elevation.

[0047] In another rear sight unit embodiment of the multiple-zero sighting device, a first sight element is located on a rear side of a pivot arm and a second sight element is located on a front side of the pivot arm. See FIGS. 7–17. Both the first and second elements are on a single rear sight unit, which rear sight unit is typically used in conjunction with an elevation-adjustable front sight (such as a blade, post or fin) unit on the front end of the firearm. Again, such systems may include a total of two windage adjustments (both on the rear sight) and three elevation adjustments (two on the rear sight and one on the front sight). For an ammunition or a range that requires a higher elevation adjustment, the pivot arm may be swung to a raised position and the sight on the rear side of the pivot arm is used. Once the pivot arm is in the raised position, elevation of this sight element is further adjusted by sliding the sight element up and down the pivot arm. Windage adjustment for this sight element is done by moving the entire pivot arm transversely in relation to the firearm. For an ammunition or range that requires a lower elevation adjustment, the pivot arm may be swung to a lowered position, which moves a sight element on the front side of the pivot arm into operable position. When the pivot arm is in the lowered position, elevation of this sight element is adjusted by controlling the acute angle between the pivot arm and the firearm. Windage adjustment for this sight element is done by moving the sight element transversely relative to the pivot arm.

[0048] In another alternative sight system embodiment, a rear sight unit has two moveable sight elements, with one of said sight elements having both a windage adjustment and an elevation adjustment, and this rear sight unit is used in cooperation with a front sight unit comprising a sight element having both a windage adjustment and an elevation adjustment. See FIGS. 18–22. This way, the system comprises two separate windage adjustments and two separate elevation adjustments for the multiple zeros that are divided between the two sight units—one of each on the rear unit and one of each being on the front unit.

Referring Specifically to the Figures:

[0049] FIGS. 1–6 show some, but not the only, embodiments of a front and rear sight system for a firearm, wherein the rear sight unit features a pivotal L-shaped frame having two separate sight elements. One sight element is located on each arm of the L-shaped frame. The sight elements are flipped into operable position by pivoting the L-shaped frame. Each sight element on the rear right unit has separate windage and elevation controls.

[0050] Referring to FIGS. 7–17, there is shown one, but not the only, embodiment of a rear sight unit, wherein the rear sight unit features two sight elements on a single pivotal arm. Preferably, the two sight elements are located on opposites sides of the pivot arm. The sight element on the front side of the pivot arm is used when the arm is pivoted to the upright position. The sight element on the rear side of the pivot arm is used when the arm is pivoted down toward the firearm.

[0051] Referring to FIGS. 18–22, there is shown one, but not the only, embodiment of a sight system having a rear sight unit comprising two sight elements on a moveable L-shaped frame. The L-shaped frame rotates on an axis near the junction of the base and the stem of the “L” to one sight element at a time into the line of sight. A windage and an elevation adjustment are provided only for one of the sight elements. The other sight element is moveable into the line of sight by virtue of the L-shaped frame moving, but is otherwise a “fixed” sight. A cooperating front sight unit features a windage adjustment and an elevation adjustment.

FIGS. 1–6:

[0052] Referring to FIGS. 1–6, an embodiment of an adjustable sighting device for buckshot and slug ammunition in a non-rifled shotgun is presented. The sighting device finds application to a variety of shooting situations. However, the adjustable sight may be particularly useful in situations where a diverse range of ammunition types may be used and carrying multiple firearms is impractical, undesirable or impossible. Typically, the sighting device is used on shotguns or other smoothbore firearms. However, the sighting device may be used whenever variable ammunition are used.

[0053] The sighting device preferably comprises adjustable front 10 and rear 20 sight units. As shown in FIG. 1, the front and rear sight units are generally secured to the upper surface of the shotgun muzzle 30 and action 40, respectively. The front sight unit 10 may be a blade sight such as those typically used on rifles. Preferably, the rear sighting apparatus (unit) 20 includes both a hollow ring 50 and a V-shaped notch 60 through which the front sight may be viewed. These elements (50, 60) may be easily interchanged as the demands of the shooting situation change. Typically, the front sight is viewed through the hollow ring to align shots taken with buckshot-type ammunition and the V-shaped notch is used to align shots taken with slug loads.

[0054] The front sight unit 10 is secured to the muzzle 30 of the shotgun barrel 31 via a sight base 12, as shown in FIG. 2A. The sight base 12 preferably comprises two substantially semi-circular pieces which conform to the exterior dimensions of the shotgun barrel 31. The pieces of the sight base may be joined with screws 13, or other fasteners, to clasp the muzzle 30, as shown in FIG. 2B. In some situations, it may be necessary to include a space between the pieces, or a cavity, which accommodates a conventional bead sight 14 beneath the base 12, as shown in FIG. 2C. The pieces of the sight base 12 may be constructed of steel, steel alloys, or other suitably rigid materials. Preferably, frictional engagement of the shotgun barrel 31 or bead sight 14 prevents axial movement of the sight base along the length of the barrel. However, other means of securing the sight base may be employed such as, for example, adhesive, as long as the bore's interior is not disturbed.

[0055] In this embodiment, the uppermost surface of the sight base 12 is generally flat to accommodate the blade 16. The blade may comprise a fin 17, which is fixedly secured to a mount 18. The mount is generally flat. The fin 17 may be joined to the mount 18 via welding, or the fin and mount may be manufactured as an integral unit. The cross section of the blade as viewed from the shotgun muzzle 30 may be generally in the shape of an inverted “T” with the fin extending vertically above its mount, as shown in FIG. 3A. The blade 16, specifically the mount 18 in the preferred embodiment, may be secured to the flat upper surface of the sight base with screws or other fasteners. FIGS. 3 and 2C illustrate the preferred mechanism for joining the blade 16 to the sight base 12.

[0056] In some situations, a larger blade may be necessary to properly calibrate the sighting system. A detachable negative minute fin 100 may be provided to increase the height of the blade 16 when necessary, as shown in FIG. 3B. The negative minute fin 100 may attach to the lower fin 17 in a number of ways. For example, the negative minute fin 100 may be screwed or snapped onto the lower fin 17, or the lower fin 17 may include a small orifice for receiving, and frictionally engaging, a small pin extending from the base of the negative minute fin. Thus, the overall height of the front sight 10 may be adjusted to the demands of the circumstances as long as the front sight 10 may be viewed through the rear sight 20 to suggest an appropriate sighting plane.

[0057] The rear sight unit 20 comprises two independent sighting elements which may be interchanged to facilitate alignment of either buckshot or slug-type ammunition. The functioning components of the rear sight unit 20 are preferably contained within a housing 22, as shown in FIGS. 4A and 4B. The housing 22 protects the moving parts of the sighting device and may also help to channel the shooter's vision in the proper direction. The rear sight housing 22 is preferably mounted to the firearm 201 above the action 40 with screws or other fasteners, as shown in FIG. 1. The positioning of the rear sight unit 20 relative to the centerline of the action 40 may be adjustable to facilitate windage calibrations. In a preferred embodiment, a generally cylindrical, rotatable shaft 24 extends between opposing walls of the housing 22. In this embodiment, the shaft 24 operates like a worm gear to move the internal components of the rear sight apparatus in a direction generally perpendicular to the barrel 31 of the firearm 201 for windage adjustment. The shaft 24 is preferably rotated manually by turning a dial 26, such as the one shown in FIGS. 4A and 4B, which is operably connected to the shaft 24 external to the rear sight housing 22. Adjusting the dial 26 rotates the threaded shaft 24, which moves both sight components together, transversely to the sight 20 longitudinal axis L. This serves to adjust windage for the ring sight 50. To provide separate windage adjustment for the notch sight 60, a separate (additional) windage adjustment 61 is provided that moves sight 60 transversely relative to sight 50.

[0058] Additional adjustability features may be built into the rear sight apparatus. In the embodiment of FIGS. 4–5, an important feature comprises a mechanism for alternating between the hollow “ghost” ring 50 used for buckshot-type ammunition and the V-shaped notch 60 used with slug-type loads. While the inventor envisions that flipping, sliding, rotating or other such mechanisms may be used to interchange the different sighting elements, the embodiment of FIGS. 4–5 features the V-shaped notch 60 and the ghost ring 50 attached to a pivoting “L” shaped mount 70. The “L” shaped mount of the preferred embodiment pivots about its elbow at approximately point B. In this arrangement, the separate elements form a single pivoting unit and are separated by generally a right angle, as illustrated in FIG. 5. Consequently, flipping the V-shaped notch 60 into the line of sight pivots the ghost ring 50 out of the sight plane and vice versa, as illustrated in FIG. 5. Applying slight pressure to the pivoting system flips the sights. Relatable clasps, or other mechanisms, may be desirable to fix the sights in a given position. Alternatively, rotating dials or gears may pivot the sighting elements to minimize contact with delicate or sensitive components of the rear sight units 20.

[0059] When the desired sighting element is positioned within the sight plane, windage and elevation calibrations may be accomplished by adjusting the appropriate components. As mentioned above, windage adjustments may be made for the V-shaped rifle sight 60 by turning the windage screw 61 of FIG. 5 clockwise or counterclockwise. Adjustments are preferably made using a screwdriver reaching through an access hole 62 in the sight housing, such as the one shown in FIG. 5. Preferably, such adjustments are made on a target range where accurate calibrations may be made. In addition, these adjustments are preferably made a single time, prior to engaging in shooting activities requiring variable ammunition.

[0060] In this embodiment, gross adjustment of both rear sighting arrangements (i.e. ghost ring 50 and notch 60) may be accomplished by tightening or loosening the spring-loaded screw 80 of FIG. 5. The internal components of the rear sighting system are preferably situated atop an elevated sight base 90. Preferably, the elevated sight base 90 pivots around point A and may, therefore, be raised or lowered by adjusting the spring-loaded screw 80. Preferably, the sighting system includes a plurality of variable-height stencils 112 (see 112, 112′, 112″, and 112′″ in FIGS. 6a–6d). Fine adjustment of the individual rear sighting components may be accomplished by adjusting the height of the stencils 1112. The ghost ring 50 and notch 60 stencils may be adjusted by loosening setscrews 51 or 63, respectively, rasing or lowering the stencils 112, and then retightening the setscrews 51 or 63. Alternatively, the stencils 112 may be removed and replaced with stencils 112 of other dimensions. Adjustment or interchanging of the stencils 112 may be necessary to compensate for windage and/or elevation calibrations made elsewhere within the rear sighting system. For example, the height of a notched stencil 112 may be made to return the V-shaped notch 60 to proper alignment after raising the overall height of the sight base 90 to calibrate the ghost ring 50.

FIGS. 7–17:

[0061] The rear sight unit 200, shown in FIGS. 7–17, may be used in combination with the front sight unit 10 of FIGS. 1–3, or with other front sights. The rear sight unit 200 comprises a rear sight pivotal assembly 210 and a rear sight base assembly 212 (see FIG. 8). The bottom surface of the rear sight base assembly 214 is preferably mounted to the top surface 202 of the firearm 201 with screws or other fasteners through holes 219 in the rear sight base assembly 212, as shown in FIGS. 7 and 8. The rear sight unit 200 is typically positioned with its longitudinal axis L parallel with the longitudinal axis L′ of the firearm 201. The rear sight pivotal assembly 210 is attached to the rear sight base assembly 212 at a pivot axle 220, as shown in FIG. 9.

[0062] In this embodiment, the pivot axle 220 is a generally cylindrical, rotatable shaft that extends between opposing walls of the rear sight base assembly 212. In this embodiment, the pivot axle 220 is treatably engaged with a female surface of the rear sight pivotal assembly 210 (see FIG. 11). Preferably, the pivot axle 220 is rotated manually by turning a knob 218 that is operably connected to the pivot axle 220 on an external side of the rear sight base assembly 212, as shown in FIGS. 8 and 11. As the pivot axle 220 rotates, the rear sight pivot assembly 210 moves transversely in relation to the longitudinal axis L′ of the firearm 201, which allows for windage adjustment of the rear sight pivot assembly 210.

[0063] The rear sight pivotal assembly 210 comprises a pivot arm 222, a close range sight assembly 231, and a long range sight assembly 232. The pivot arm 222 pivots on axle 220 and pivots between angles generally perpendicular to the firearm's longitudinal axis L′ and generally parallel to the firearm's longitudinal axis L′. When the pivot arm 222 is in a perpendicular position, the long range sight assembly 232 is in optimum position for sighting-in long range ammunition, such as a slug cartridge. As the pivot arm 222 is moved to angles more parallel to the firearm's longitudinal axis L′, the close range sight assembly 231 is in optimum position for sighting-in short range ammunition, such as a buckshot cartridge. A detent system 221 frictionally engages the rear side of the pivot arm 222 to limit the pivot arm's 222 rotation and/or to latch the arm 222 in the generally vertical position; other latches or locks may be used.

[0064] The close range sight assembly 231 may be attached to the front side of the pivot arm 222 either as an integral part of the pivot arm, as shown in FIG. 8, or with the close range sight assembly 231 attached to the pivot arm 222 by a screw or other fastener. The long range sight assembly 232 may be attached to the rear side of the pivot arm 222 with a screw 234, as shown in FIG. 11, or with other fastening mechanisms that allow for height adjustment of the long range sight assembly 232.

[0065] The long range sight assembly 232 preferably includes a long range elevation adjustment frame 233, a screw 234 for locking and releasing the frame 233 in a desired position, a left flap 235 of the long range elevation adjustment frame 233, a right flap 235′ of the long range elevation adjustment frame 233, and a long range sight notch 238 (see FIG. 11). Preferably, when the pivot arm 222 is in a position perpendicular to the longitudinal axis L′ of the firearm 201, the long range sight assembly 232 is fully visible to the user for lining up the notch 238 with the front sight 10. The windage is adjusted for the long range sight assembly 232, by manually turning the knob 218, which moves the pivot arm 222 transversely, in turn moving the long range sight assembly 232 transversely. The long range elevation adjustment frame 233 is secured in a position on the front side of the pivot arm 222 with a screw 234. In this embodiment, the long range sight notch 238 is located at the bottom of the frame 233, as shown in FIG. 11. To adjust the elevation of the long range sight notch 238, the firearm 201 user unscrews the screw 234 and raises or lowers the frame 233 depending on the desired elevation, as shown in FIGS. 12 and 13. In this embodiment, the left 235 and right 235′ flaps of the frame prevent the frame from tilting when the screw 234 is loosened (see FIG. 11). The user secures the frame 233 and notch 238 at the desired elevation by tightening the screw 234, and then is able to aim the firearm 201 by looking through the long range sight notch 238. Preferably, once the elevation and windage of the long range sight assembly 232 have been adjusted, the user can adjust the windage and elevation for the close range sight assembly 231.

[0066] The close range sight assembly 231 preferably includes a housing for close range windage adjustment 224, a close range sight member 226, a close range sight notch 228, and a close range windage adjustment 230 (see FIGS. 8 and 10). Preferably, the close range windage adjustment 230 is located in the housing 224, and may be a threaded rotatable shaft that treatably engages the close range sight member 226. As the close range windage adjustment 230 is rotated, the close range sight member 226 moves transversely in relation to the pivot arm 222 and, hence, the firearm 201 longitudinal axis L′, in turn moving the close range sight notch 228. The transverse movement of the close range sight member 226 and notch 228, permits the firearm 201 user to adjust the windage of the close range sight 231.

[0067] In order to adjust the elevation of the close range sight assembly 231, the firearm 201 user pivots the pivot arm 222 to a desired angle more parallel to the firearm 201 longitudinal axis L′. The pivot arm 222 is secured at the desired angle by resistance from the detent system 221 and with a sliding elevation adjustment member 216 that the user moves longitudinally along the top surface of the rear sight base assembly 215, so it abuts against the long range sight assembly 232 at various locations depending on the desired elevation, as shown in FIGS. 14–17. The sliding elevation adjustment member 216 is held in the desired position along the top surface of the rear sight base assembly 215 with a set screw 217 (see FIG. 9). The edges of the channel in which the member 216 slides may overhang the member 216 to retain the member 216 from falling out of the base 213. Once the close range elevation and windage have been adjusted, the user can aim the firearm 201 by looking through the close range sight notch 228.

[0068] An alternative apparatus my be used to adjust the acute angle of the pivot assembly 210 to the base assembly 212. For example, instead of the sliding member 216 “holding up” the pivot assembly 210, a different latch, lock, or wedge member may adjust or secure the assembly 210 at any location within a desired continuous range of acute angles, or at incremental locations within a desired non-continuous range of acute angles. Typically, the pivotal assembly 210 will be (for long range) either in a generally vertical position (preferably vertical±20 degrees) or (for close range) at various angles in the range of about 0–25 degrees from the firearm 201 longitudinal axis L′.

[0069] While notches 228 and 238 are illustrated as rectangles, other shapes and styles of sight surfaces may be used, for example, peeps, rings, or V-shaped notches. Further, frame 233 may be redesigned to be a different shape and have a different attachment or elevation system. For example, a U-shaped frame with a notch or simply a bar with a notch may be used with a screw, screws, pins, ratchets, clips, latches/locks, or other fasteners adjustably connecting the frame or bar to a surface of the pivot arm 222, preferably not blocking the aperture 240. Using a U-shaped frame, bar, or other sight member of smaller/shorter dimensions than the illustrated frame 233, and/or using adjustment mechanisms other than the screw 234, may reduce obstruction of the aperture 240. Aperture 240 is one embodiment of an opening/hole through the pivot arm 222, which serves as a “window” through the arm 222. This aperture/window allows the user to see through the arm, so that he/she may see both the notch 238 and the front sight 10 at the same time and align them, during both sighting-in of the firearm and aiming for shooting with the chosen ammunition.

[0070] In use, the firearm 201 user will sight-in the firearm 201 using a first-type ammunition, for example, slug-type cartridges. He/she may begin with the basic form of the front sight 10 (without extension fin 100). If this front sight configuration does not allow the user to sight-in (“zero”) the firearm properly by adjusting elevation and windage of the rear sight unit 200, then the front sight 10 may be extended upwards to make an incremental, gross adjustment in the position of the front end of the firearm 201 (for example, lowering of the front end when the front sight is raised, for a given rear sight unit configuration). Then, with the front end of the firearm grossly adjusted by the extended front sight unit, the new grossly-adjusted position of the firearm will typically be such that rear sight unit 200 can be adjusted for elevation and windage to give the desired zeroing results. Typically, for many slug applications, the front sight unit will be extended and the pivot arm 222 in the vertical position.

[0071] To sight-in the second “zero”, ammunition may then be switched, and the rear sight pivotal assembly 210 may be pivoted to the proper angle relative to the base assembly 212, controlled by the sliding member 216 and determined by trial and error. Windage is also adjusted via adjustment 230. The front sight 10 may also be adjusted or switched-out to another fin 17 if needed for the second ammunition.

[0072] The result is a dual-zero sight system, with two zeroing systems for two types of ammunition. While the system may be used for different ranges and a single ammunition, the specials features are especially effective for the very different trajectories that different ammunition can exhibit.

[0073] Other adjustment mechanisms are envisioned for the elevation and windage adjustments. For example, see earlier comments on alternative mechanisms for locking/latching the pivot arm at various angles for elevation adjustment. Further, while it is preferred that the sight member 226 does not slide longitudinally along the pivot arm, some embodiments may include such an elevation adjustment for sight member 226 instead of, or in addition to, the elevation adjustment provided by the pivoting arm. Other mechanisms may move/secure the second sight member (frame 233) up and down on the pivotal frame, for example, as in the above comments regarding embodiments of U-shaped frames and/or bars. For windage adjustment, other mechanisms besides the worm-style, threaded adjustments (220/218 and 230) may move the sight member 226 transversely to the pivot arm and the pivot arm 222 transversely to the base assembly 212: for example, a ratchet mechanism, a slide and lock mechanism, a slide mechanism wherein the user unlocks the sight member 226 and slides the member 226 to align with pre-marked calibration indicia and re-locks the member 226, or others.

FIGS. 18–22:

[0074] Some embodiments may include a rear sight unit 300 that has two moveable sight elements, wherein only one of said sight elements is adjustable for windage and adjustable for elevation. In such embodiments, the front sight unit 310 may have a single sight element that is adjustable for windage and for elevation. Thus, the two separate windage and two separate elevation adjustments are separated into two sight units (300, 310) that are distanced from each other. This sighting system preferably consists of one windage and one elevation adjustment on a sighting element of each of the rear and the front sight units, and the rear sight unit further comprising a second sighting element that moves into the line of sight but is otherwise not adjustable. Referring to FIG. 18, one may see the rear sight unit 300 and the front sight unit 310, generally at opposite ends of the firearm barrel.

[0075] Rear sight unit 300 has first sight element 311 and second sight element 312 provided on an L-shaped frame with a first leg 315 and a second leg 320 at approximately 90 degrees to each other. The L-shaped frame is rotatably connected to a base 316, which may be attached by screws 317, for example, to the firearm.

[0076] Sight element 311 may comprise a V-notch, aperture, ring, or other sight shape. In FIGS. 18, 19, and 21, the element is portrayed as having a V-notch 313. Element 311 is preferably not adjustable in its transverse position or its longitudinal position on the first leg 315.

[0077] Sight element 312 is attached to second leg 320 and is provided with an aperture ring 314, but other sight elements may be used. Sight element 312 is adjusted by windage adjustment system 330 and elevation adjustment system 340. Adjustment system 330 may comprise a threaded shaft 332 with a head 333 on which the sight element 312 rides. By turning head 333, threaded shaft 332 moves the sight element 312 transversely either way (up or down in FIG. 21), depending upon which way the head 333 is turned. Separately, screw 334 may be used to loosen and allow adjustment of the connection between element 312 and its holding bracket 335, so that the element 312 may slide longitudinally on the bracket 335 (with slot 336 sliding on screw 334).

[0078] Front sight unit 310 comprises a base 350, a housing or guard walls 352, 353, and adjustable post system 354. The post system rides on a threaded shaft 356, which is rotated by screw head 358 and, upon rotation, moves the post system 354 transversely (up and down in FIG. 22, depending upon which way the head 358 and shaft 356 are turned), for windage adjustment. Other windage adjustment methods and apparatus may be used.

[0079] The post 360 may also be raised and lowered (up and down in FIG. 20) for elevation adjustment. The elevation adjustment shown in FIGS. 20 and 22 comprises a spring-loaded detent button 362 that may be pushed down, to move the button 362 out of the way of rotation of the post on its threaded axis. By rotating the post 360 in one direction or the other, it will be raised or lowered, depending on the direction of the threads. Post rotation is facilitated by gripping/turning prongs 364 that protrude radially from the post. When the desired adjustment is completed, the detent button 362 may be released and it will pop up between two of the prongs to maintain the post 360 in the desired position by preventing further rotation of the post. Other post, blade, or fin sight element designs may be used, and other ways of raising or lowering said element may be used.

[0080] In use, the rear sight unit 300 and the front sight unit 310 are installed on a firearm. A first ammunition is loaded into the firearm, and the first zero system is sighted-in. This will typically comprise pivoting the rear sight unit 300 into the position shown in FIG. 19, with the first sight element 311 in the upward position, and the firearm is sighted-in by adjusting the front sight unit 310 for both windage and elevation. Then, an alternative ammunition of interest is loaded, and the second zero system is sighted-in. This will typically comprising pivoting the L-shaped frame of the rear sight unit 300 to its other position, with the second element 312 in a raised position (90 degree rotation clockwise from the position shown in FIG. 19). Then, without changing the front sight unit 310 windage or elevation adjustments, the rear right unit 300 is adjusted. That is, the windage adjustment (via head 333 and shaft 332) is conducted and elevation adjustment is conducted (via screw 334, slot 335 and bracket 336). Thus, zeroing a single firearm for each of two types of ammunition is possible.

[0081] One will note that alternative arrangement are also possible. There are several configurations of the multiple-zero sighting system that may group, for example, two separate windage adjustments and two separate elevation adjustments on a single sight unit or distribute said two separate windage adjustments and two separate elevation adjustments between the front and rear sights.

[0082] For example, a front sight unit could have two moveable/pivotal sighting elements, and each could have separate windage and elevation adjustments. Such a front sight could cooperate with a fixed rear sight or a rear sight with only elevation adjustment. In other words, this embodiment would be similar to switching the position (rear to front) of the sight units 20 and 10 in FIGS. 1–6, and 210 and 10 of FIGS. 7–17. The inventor envisions that such arrangements would be clumsy and less desirable.

[0083] Also, a front sight unit with two moveable/pivotal sighting elements could be used, with only one of the sighting elements having a windage adjustment and a elevation adjustment. Such a front sight could cooperate with a rear sight unit with a single sight element having both windage and elevation adjustment. In other words, this embodiment would be similar to switching the position (rear to front) of the sight units 300, 310 in FIGS. 18–22. The inventor envisions that such arrangements would be clumsy and less desirable.

[0084] The preferred sighting units are operated manually, without power sources other than the user of the device, and without a motor or electronics. The user may grasp various parts of the sighting unit to affect the switch between sighting elements, as long as the parts or provided handles/grips are sturdy enough to prevent damage from normal operation. The interchanging of sight elements may be done by manually rotating, flipping, or sliding the desired sight element into the operable/usable position, which, due to the linkage/connection between the elements, moves the unnecessary element out of the sight path. Alternatively, the interchanging may be done by manually moving the unnecessary element out of the way, which, due to the linkage/connection, moves the desired element into the operable/usable position.

[0085] While the terms “long range” and “close range” are used in the Detailed Description, for example, to describe first and second sight members installed on the pivot arm of the preferred embodiment, these terms are not necessarily intended to limit those sight members or the operation of the invented devices to long range shooting with the pivot arm in the upright, generally vertical position, or to close range shooting with the pivot arm in a lowered/generally-horizontal position. Depending upon the characteristics of the ammunition being selected and the desired application/range, the two sight or zero systems on the rear sight unit, or the sight or zero systems of the combined front and rear sight units, may be used differently and/or for different ranges. After viewing the Figures and the Description, one may see that the general principles of the invention may be applied with other shapes, positions, movements, and operations for the multiple sights, while still being within the scope of the invention. For example, one may see that many embodiments of the rear sight unit may be rotated 180 degrees on the firearm so that the pivot arm pivots down toward the front end of the barrel, rather than pivoting down toward the butt of the gun. Some changes in shape and/or dimensions of the pieces-parts of the device might then be needed, for example, to account for the slightly nearer location of the sights to the user's eye, but many or all issues related to the orientation on the firearm may be accommodated during the sighting-in process and/or by modifications in the front sight unit. Therefore, the terms “front” and “rear” of the sighting device are used for clarity in describing the especially-preferred embodiment of the invention, but are not necessarily intended to limit the invention to the particulars disclosed in the Drawings and Detailed Description.

[0086] Although this invention has been described above with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to these disclosed particulars, but extends instead to all equivalents within the scope of the following claims.