Abstract:
A turret knob comprises an adjustable member, an engagement member and a plurality of stop members. The adjustable member is capable of being adjustably positionable about an axis of rotation. The engagement member is coupled to the adjustment member, and a relative position of the engagement member with respect to the axis of rotation corresponds to a position of the adjustable member as the adjustable member is adjustably positioned about the axis of rotation. The plurality of stop members are each selectably positioned about the axis of rotation. Each stop member is capable of interfering with the engagement member and blocking movement of the adjustable member as the adjustable member is adjustably positioned about the axis of rotation. The adjustable member is adjustably positionable about the axis of rotation between adjacent stop member positions.

Description:
[0001]    CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
         [0002]    The present Patent Application claims priority to U.S. Provisional Patent Application Ser. No. 61/074,646, filed Jun. 22, 2008, entitled “Operator Selectable Stop (OSS) Turret Knob,” and PCT Patent Application PCT/US2008/048183, filed Jun. 22, 2009, entitled “Operator-Selectable-Stop Turret Knob,” both having been invented by Bernard T. Windauer, and the disclosures of both being incorporated by reference herein. 
     
    
     BACKGROUND 
       [0003]    The subject matter disclosed herein relates to an optical enhancing device, such as a telescopic observation sighting device or individual shoulder (or hand-fired) firearms sighting device (telescopic sight herein). Embodiments according to the subject matter disclosed herein may also be used with any optical enhancing device containing adjusters, such as a microscope, telescope, etc. For purposes of illustration, it will be assumed herein that the optical enhancing device is a telescopic firearms sight. 
         [0004]    A telescopic sight, typically used to aim a firearm, is usually mounted on the firearm. An adjustment knob on a telescopic sight is typically used for changing a setting of an adjuster, for example, elevation, crossrange (also “windage” herein), or parallax, of the telescopic sight. Parameters such as elevation, crossrange, and parallax, may be painstakingly set in order that the projectile fired from the firearm hit a specific target. Once set for a particular target parameter, the setting preferably remains unchanged until after a shot is fired at the target. 
         [0005]    Existing telescopic sighting systems for civilian, law enforcement, and military firearms typically utilize two types of adjustment knobs. The first type of adjustment knob is allowed to rotate freely. The knob is permanently exposed, or is uncovered by removing a cover cap to make an adjustment. The second type of knob is a locking knob in which the lock must be released prior making an adjustment. Around the circumference of both types of knobs are numerals and index marks to indicate the rotational setting of the knob with respect to a fixed datum mark. To adjust the knob of the telescopic sight so that the projectile impacts the target at a known distance requires an operator to visually check the reference marks against the datum mark to verify the settings are correct. In some circumstances, such as a military or tactical application in which the telescopic sight is used in the dark, the operator cannot visually check the telescopic sight setting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The subject matter disclosed herein is illustrated by way of example and not by limitation in the accompanying figures in which like reference numerals indicate similar elements and in which: 
           [0007]      FIG. 1A  depicts an exploded assembly cross-sectional view of an exemplary embodiment of an Operator Selectable Stop Turret Knob (OSSTK) according to the subject matter disclosed herein; 
           [0008]      FIG. 1B  depicts the down position and the up positions of the exemplary embodiment of an OSSTK according to the subject matter disclosed herein; 
           [0009]      FIG. 2A  depicts an exploded assembly cross-sectional view of an exemplary embodiment of a Set-Screw OSSTK (SSOSSTK) according to the subject matter disclosed herein; 
           [0010]      FIG. 2B  depicts an assembled cross-sectional view of the exemplary embodiment of the SSOSSTK according to the subject matter disclosed herein; 
           [0011]      FIG. 3A  depicts an exploded assembly cross-sectional view of an exemplary embodiment of a Spring Bar/Stop Ring OSSTK (SBSROSSTK) according to the subject matter disclosed herein; 
           [0012]      FIG. 3B  depicts an assembled cross-sectional view of the exemplary embodiment of the SBSROSSTK in a “zeroed” configuration according to the subject matter disclosed herein; 
           [0013]      FIG. 3C  depicts a top cross-sectional view of the exemplary embodiment of the SBSROSSTK at a first stop configuration taken at View A-A in  FIG. 3B  according to the subject matter disclosed herein; 
           [0014]      FIG. 3D  shows a top view of an exemplary embodiment of a stop ring for the exemplary embodiment of the SBSROSSTK according to the subject matter disclosed herein. 
           [0015]      FIG. 4A  depicts an exploded assembly cross-sectional view of an exemplary embodiment of a Pre-Set Stop Ring Turret Knob (PSSRTK) according to the subject matter disclosed herein; 
           [0016]      FIG. 4B  depicts an assembled cross-sectional view of the exemplary embodiment of the PSSRTK in a “zeroed” configuration according to the subject matter disclosed herein; 
           [0017]      FIG. 4C  shows a top cross-sectional view of the exemplary embodiment of the PSSRTK at a first stop configuration according to the subject matter disclosed herein; and 
           [0018]      FIG. 4D  shows a top cross-sectional view of an exemplary embodiment of a stop ring for the exemplary embodiment of the PSSRTK according to the subject matter disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not to be construed as necessarily preferred or advantageous over other embodiments. 
         [0020]    The subject matter disclosed herein provides an adjustment knob that has a mechanically or tactile indication of the desired sight setting. Additionally, the subject matter disclosed herein provides in one exemplary embodiment a knob having a settable mechanical/tactile setting that is selectably set by an operator for special-sighting applications. In another exemplary embodiment a knob having a pre-set mechanical/tactile setting for specific standard ammunition types. 
         [0021]    The subject matter disclosed herein also provides an adjustment knob that has either a single or multiple mechanical stops that can be set by an operator when a specific single or multiple sight settings are desired for specific factory or custom loaded ammunition types. The subject matter disclosed herein additionally provides an adjustment knob that has either a single or multiple mechanical stops that can be pre-set by an armorer for a specific ammunition type. 
         [0022]    The subject matter disclosed herein provides an adjustment knob for an optical setting, such as elevation, windage, parallax, or illuminated reticle power control for an optical-based instrument, such as a telescopic sighting system, a telescope or a microscope, that can be mechanically stopped at a single location or at multiple locations, thereby eliminating the need to view the numerical or linear index marks to indicate sight settings. Accordingly, one exemplary embodiment of the subject matter disclosed herein allows a user to mechanically set the stops of the adjustment knob, thereby permitting a desired adjustment of an optical or power setting without needing to visually observe the value of the adjustment during use. Thus, optical or power settings set by a user are reliably repeatedly made during use without the need for visual verification regardless of the environmental conditions. 
         [0023]    In one exemplary embodiment, the subject matter disclosed herein allows an operator (or shooter) the ability to adjust a turret knob to stop, or be “confined,” at a numerical (rotational) setting that corresponds to a desired projectile Point Of Impact (POI) at a desired range. The subject matter disclosed herein allows the operator to set a bottom stop position and multiple stops every ½ mil (or minute-of-arc) rotational position. Additionally, one exemplary alternative embodiment of the subject matter disclosed herein allows an operator (or shooter) the ability to adjust the turret knob to stop at a numerical (rotational) setting that corresponds to a desired projectile point of impact (POI) at a desired range. The design allows the operator to have a “zero” location for the bottom end of the scope adjustments and multiple stops at rotational settings chosen by the operator. 
         [0024]      FIG. 1A  depicts an exploded assembly cross-sectional view of a first exemplary embodiment of an Operator Selectable Stop Turret Knob (OSSTK)  100  according to the subject matter disclosed herein. As shown in  FIG. 1A , OSSTK  100  comprises a stop-knob sleeve  101 , a stem hub  102 , a hub cap-screw  103 , a turret-knob cap  104 , an index skirt  105 , and a release button  106 . 
         [0025]    Stop-knob sleeve  101  is affixed in a fixed position in a well-known manner to a scope body (not shown). Stem hub  102  is held to the rotating (movable) stem of the scope (not shown) via hub cap-screw  103  and is adjustably positionable in a well-known manner about an axis of rotation  126 . When the bottom position and desired stop points are determined through shooting, two turret knob cap cap-screws  107  are removed and turret-knob cap  104  and index skirt  105  are removed. Hub cap-screw  103  is loosened and stem hub  102  is rotated so that a stop pin  108  that is inserted through a hole  111  in release button  106  is pointing to the rear of the scope body so that it is in line with a fixed datum mark (not shown) on stop-knob sleeve  101 . Hub cap-screw  103  is then tightened to secure stem hub  102  to the scope rotating stem (not shown). 
         [0026]    Release button  106  comprises an aperture  111  that passes radially through the longitudinal axis of release button  106 , and a blind aperture  112  that extends along the longitudinal axis. A spring  113  fits inside blind aperture  112  and is held in place by a button-release plunger  114  that comprises an aperture  115  that corresponds to aperture  111  in release button  106  so that spring  113  and plunger  114  are held captive inside blind aperture  112  when stop pin  108  is inserted through apertures  111  and  115 . When assembled, release button  106  fits inside blind aperture  116  of stem hub  102  so that stop pin  108  protrudes through aperture  117  of stem hub  102 . An O-ring  118  fits into annular slot  119  to form a seal for release button  106  at turret-knob cap  104  when OSSTK  100  is fully assembled. 
         [0027]    Returning to the setting procedure, ball bearings  109  (of which only one ball bearing  109  is indicated) are then inserted into selected holes  110  of stop-knob sleeve  101  to provide stop locations for desired settings. It should be understood that in an exemplary alternative embodiment, stop members, such as a stop pins, could be substituted for ball bearings  109 . In yet another exemplary alternative embodiment, the stop members could be a combination of ball bearings  109  and stop pins. When a rotational setting is determined through shooting or predetermined through calculation, the assembly is rotated to that position. The knob cap  104  and index skirt  105  are removed and the relative position of stop pin  108  is compared to a hole  110  in stop-knob sleeve. Into this hole is placed a ball bearing  109  to create a stop position. This procedure is repeated for the desired number of stop positions. Index skirt  105  is then slipped over stop-knob sleeve  101  to retain ball bearings  109  in the selected holes  110 . 
         [0028]    Turret-knob cap  104  is then secured via cap screws  107 , thereby clamping index skirt  105  to stem hub  102  so that the numerical “zero” index mark (not shown) etched on the outside circumference of index skirt  105  aligns with the fixed datum mark (not shown) on stop-knob sleeve  101 . O-ring seal  120  fits into annular slot  121  in turret-knob cap  104 , thereby sealing the mechanical fit of turret-knob cap  104  onto index skirt  105  when OSSTK  100  is fully assembled. Similarly, o-ring seal  122  fits into annular slot  123  in stem hub  102 , and o-ring seal  124  fits into annular slot  125  when OSSTK  100  is fully assembled. 
         [0029]    OSSTK  100  is operated by rotating index skirt  106  and turret-knob cap  104  until stop pin  108  interferes with (bumps into) the ball bearing  109  located at the first stop position. At this setting, the scope allows the operator to fire the firearm and have the projectile impact the target at the desired position at the first target range. To continue on to the next stop setting, release button  106  is depressed by the operator (accessible on the top of the turret-knob cap  104 ) so that stop pin  108  drops below the ball bearing  109 , thereby allowing stem hub  102 , index skirt  105 , and turret-knob cap  104  to continue to rotate to the next setting. 
         [0030]      FIG. 1B  depicts the fully down position and the fully up positions of OSSTK  100  as OSSTK  100  is rotated from one extreme to the other. The left portion of OSSTK  100  shown in  FIG. 1B  is depicted in the fully down position, while the right portion of OSSTK  100  is depicted in the fully up position. As OSSTK  100  is rotated in the direction from the fully down position towards the fully up position or in the direction of the fully up position to the fully down position, each operator-selectable stop provides a stop position that can be overridden by pressing release button  106 . Between operator-selectable stops, OSSTK  100  can be rotated for fine adjustments. To move beyond an operator-selectable stop, the release button must be pressed. 
         [0031]    A second exemplary embodiment of the subject matter disclosed herein provides the ability to “confine” the rotating assembly into a desired stop position with the ability to rotate a predetermined number of “clicks” on either side of the stop position. In particular, the second exemplary embodiment allows intermediate adjustments between stops. 
         [0032]      FIG. 2A  depicts an exploded assembly cross-sectional view of an exemplary embodiment of a Set Screw OSSTK (SSOSSTK)  200  according to the subject matter disclosed herein.  FIG. 2B  depicts an assembled cross-sectional view of the exemplary embodiment of Set Screw SSOSSTK  200  according to the subject matter disclosed herein. 
         [0033]    As shown in  FIG. 2A , SSOSSTK  200  comprises a turret base assembly  201 , a hub assembly  202  and a knob assembly  203 . Turret base assembly  201  comprises a turret base  204 , a base zero pin  205 , and a plurality of knob base screws  206 , of which only one knob base screw is shown. Turret base assembly  201  is affixed in a well-known manner to a scope body (not shown) in a fixed position, such as by knob base screws  206 . An O-ring  207  is used to form a seal between the bottom of turret base assembly  201  and the scope body. An O-ring  208  is used to form a seal between turret base assembly  201  and hub assembly  202  when hub assembly  202  is inserted into turret base assembly  201 . 
         [0034]    Hub assembly  202  comprises a turret adjustment hub  209 , a hub adjustment cap  210 , a spade screw  211 , a cap-screw  212  and a hub cap-screw spring  213 . Hub assembly  202  also comprises a primary ratchet pin  214  and corresponding spring  215 , a secondary ratchet pin  216 , a hub adjustment cap dowel pin  217  and a hub adjustment cap guide pin  218 . Hub assembly  202  is adjustably positionable in a well-known manner about an axis of rotation (not shown) in order to make adjustments to the scope (not shown). 
         [0035]    Knob assembly  203  comprises a turret knob  219 , a knob cover cap  220 , a knob zero pin  221 , a plurality of knob stop-screws  222 , of which only one knob stop-screw is shown, and a plurality of knob set-screws  223 , of which only one knob set-screw is shown. An O-ring  224  is used as a seal when knob cover cap  220  is mounted to turret knob  219  to prevent knob stop screws  222  from becoming environmentally contaminated. 
         [0036]    Hub assembly  202  is inserted into turret base assembly  201 . An internal ring gear  225  is placed over the hub assembly  202  and on top of the turret base assembly  201  and located in position by the zero pin  205  and screws  227 . Internal ring gear  225  encircles the hub assembly  202 . Internal ring gear  225  comprises a plurality of gear teeth that are arranged around the 360° inside circumference of the ring gear. The spacing or the number of gear teeth determine how many degrees of rotation there are for each tactile “click.” The pitch (the number of threads per inc) of the threads on spade screw  211  and the degrees of rotation of hub  209  determine the movement (either extension or retraction of spade screw  211  from hub  209 ) in an axial direction to move the reticle (crosshairs) lens assembly with the scope. The spade of spade screw  211  protrudes through a slot in the scope body, therefore it does not rotate with adjustment hub  20 , but can only move vertically based on the rotation of hub  209 . Internal ring gear retainer  226  is then installed and held in place with four retainer screws  227 , of which only one retainer screw  227  is shown, that pass through apertures  228  in the internal ring gear  225  and engage apertures  229  in turret base  204 . Hub adjustment cap  210  is then inserted into turret adjustment hub  209  and held in place by hub cap-screw spring  212  and cap-screw  213 . Knob assembly  203  is then installed and held in place with two knob set screws  223 , of which only one knob set screw  223  is shown. O-ring  231  provides a seal between knob assembly  203  and turret base  204 . 
         [0037]    To zero the exemplary embodiment of the SSOSSTK  200 , the firearm is shot at the desired closest distance to the target. Knob set screws  223  are loosened and knob assembly  203  is rotated so that the base zero pin  205  and knob zero pin  221  “bump” one another at which point the “zero” numeral (not shown) etched on the outer circumference of knob assembly  203  aligns with the datum mark (not shown) of turret base assembly  201 . Knob set-screws  223  are then tightened. Knob assembly  203  can then be returned to this “zero” setting at any time to assure the projectile impacts at the same desired point of impact at the same “zeroed” distance. In some situations, approximately two “tactile” clicks are desired below the “zero” setting for an occasional shot to be taken closer than the “zero” setting or for fine “zero” sight settings due to changed ambient climatic conditions. If the two (or greater) “tactile” clicks are desired the orientation of zero pin  205  relative to the “zero” numeral on turret knob  219  can be changed. 
         [0038]    The exemplary embodiment of the SSOSSTK  200  allows an operator to have a “zero” location for the bottom end of the scope adjustments and multiple stops every ½ mil (or minute-of-arc) rotational position. 
         [0039]    To set the “number one” (or first) stop position, the knob cover cap  220  is removed and the firearm is shot at the distance desired for the first stop location. The knob assembly  203  is rotated counter-clockwise (or clockwise if the system is designed for the opposite direction) so that the “crosshair” reticle coincides with the desired projectile point of impact location at the distance for the first stop location. The knob stop screw  222  that is located directly above the datum mark (not shown) of turret base assembly  201  is screwed down (clockwise) until it stops in its hole  230 , and thereby creating an interference between knob stop screw  222  and base zero pin  205 . Knob assembly  203  can then be returned to this “stop” setting at any time to assure the projectile impacts at the same desired point at the same “stop” distance. 
         [0040]    To set the next desired stop position, the knob assembly  203  is lifted to eliminate the interference between the knob stop screw  222  and base zero pin  205  and rotated to the next desired projectile point of impact stop location at the next farthest distance. The knob stop screw  222  that is located directly above the datum mark (not shown) of turret base assembly  201  is screwed down (clockwise) until it stops in its hole. Knob assembly  203  can then be returned to this “stop” setting at any time to assure the bullet impacts at the same desired point at the same “second stop” distance. 
         [0041]    The above-described stop-setting procedure is used to set stops at any desired distance. 
         [0042]    To return to the “zero” setting, an operator only needs to lift knob assembly  203  to eliminate the interference of the knob stop screws  222  and the base zero pin  205 , and turn knob assembly  203  fully clockwise until the “zero” numeral (not shown) etched on the outer circumference of knob assembly  203  aligns with the datum mark of turret base assembly  201 . Returning to “zero” can also be “felt” when the knob no longer rotates clockwise (or counter-clockwise) when the knob assembly  203  is lifted to eliminate the interference of the knob stop screw  222  and base zero pin  205 . To return to a previously selected stop setting from the “zero” position, the operator only needs to lift knob assembly  203  to eliminate the interference of the knob stop screw  222  and base zero pin  205 , and rotate knob assembly  203  clockwise slightly. Knob assembly  203  can be released and allowed to retract, and the operator can continue to rotate knob assembly  203  clockwise until the next selected stop position is encountered, in which a knob stop screw  222  “bumps” into base zero pin  205 . If a lower stop location is desired, the operator need only repeat the stop-setting procedure until the desired stop location is achieved. This procedure is used when the knob setting numbers (etched on the outer surface of the knob assembly  203 ) cannot be visually observed. 
         [0043]    Another technique of returning to a different stop location is to lift knob assembly  203  to eliminate the interference of knob stop pins  222  and base zero pin  205 , and turn knob assembly  203  clockwise (or counter clockwise) until the corresponding “stop location” number (or intermediate number) etched on the outer circumference of knob assembly  203  aligns with the datum mark (not shown) of turret base assembly  201 . 
         [0044]    As SSOSSTK  200  is rotated in the direction from the fully clockwise position towards the fully counter-clockwise position or in the direction of the fully clock-wise position to the fully counter-clockwise position, each operator-selectable stop provides a stop position that can be overridden by lifting turret knob  219 . Between operator-selectable stops, SSOSSTK  200  can be rotated for fine adjustments. To move beyond an operator-selectable stop, turret knob  219  must be lifted. It should be understood that the exemplary embodiment of the SSOSSTK  200  can be used as a normal turret knob by not engaging (lowering) knob stop screws  222  so that they interfere with base zero pin  205 . 
         [0045]      FIG. 3A  depicts an exploded assembly cross-sectional view of an exemplary embodiment of a Spring-Bar/Stop Ring Operator-Selectable-Stop Turret Knob (SBSROSSTK)  300  according to the subject matter disclosed herein.  FIG. 3B  depicts an assembled cross-sectional view of the exemplary embodiment of SBSROSSTK  300  in a “zeroed” configuration according to the subject matter disclosed herein.  FIG. 3C  depicts a top cross sectional view of the exemplary embodiment of SBSROSSTK  300  at a first stop configuration taken at View A-A in  FIG. 3B  according to the subject matter disclosed herein.  FIG. 3D  shows a top view of an exemplary embodiment of a stop ring  323  for the exemplary embodiment of SBSROSSTK  300  according to the subject matter disclosed herein. 
         [0046]    SBSROSSTK  300  comprises a turret base plate assembly  301 , an adjustment hub assembly  302  and a turret knob assembly  303 . 
         [0047]    Turret base assembly  301  comprises a turret base  304 , a plurality of screws  305  and a zero pin  306 . Turret base  304  is fixedly attached in a well-known manner to, for example, a telescopic sight (not shown) or other optical enhancing device (not shown), such as by screws  305 . A zero pin  306  is inserted into an aperture  307  in turret base  304 . 
         [0048]    Adjustment hub assembly  302  comprises an adjustment hub  309 , internal ring gear  310 , internal ring gear retainer  311 , and a spade screw  312 . The lower portion of adjustment hub  309  fits inside an aperture  308  that passes through turret base  304 . The lower section of adjustment hub  309  threadably engages the upper portion of spade screw  312 . Spade screw  312  passes through a slot in the body of the telescopic sight (not shown) and mechanically engages in a well-known manner an optical adjustor (not shown) of the telescopic sight. Hub assembly  302  is adjustably positionable in a well-known manner about an axis of rotation (not shown) in order to make adjustments to the scope (not shown). 
         [0049]    Internal ring gear  310  fixedly fits around a larger diameter flange  313  of adjustment hub  309  and retains a spring-loaded tactile plunger  314  and a spring  315  within flange  313  of adjustment hub  309 . Internal ring gear retainer  311  retains adjustment hub  309  and spring-loaded tactile plunger  314 . Internal ring gear retainer  311  is held in place by screws  316  that extend through holes (not shown) in flange  317  of internal ring gear retainer  311  and internal-ring gear  310  to thread into turret base  304 . Three spring-loaded stop plungers  318 - 1  through  318 - 3  and springs  319 - 1  through  319 - 3  are positioned in a slot  320  in internal ring gear retainer  311 . 
         [0050]    Turret knob assembly  303  comprises a turret knob  321 , two knob locking set-screws  322  (of which only one is shown), six stop rings  323 - 1  through  323 - 6 , six stop ring set screws  324 - 1  through  324 - 6 , a retaining ring  325  to retain stop rings  323 - 1  through  323 - 6  within turret knob  321 , a stop-ring clamp screw  326 , and a stop pin  327 . Turret knob assembly  303  is installed over the assembled adjustment hub assembly  302  and retained to the top groove of adjustment hub  309  with knob-locking set screws  322 . 
         [0051]    To “zero” the exemplary embodiment of the SBSROSSTK  300 , the firearm is shot at the desired closest distance to the target with knob set screws  322  tightened. The knob assembly  303  is rotated so that the aiming point of the telescopic sight coincides with the projectile point of aim at the desired “zero” distance. Rotation of turret knob assembly  303  during the “zeroing” process rotates the adjustment hub assembly  302  to extend and/or retract the adjustment spade screw  312  which, in turn, adjusts the internal components of the optical sight (not shown). Knob set screws  322  are then loosened and knob assembly  303  is rotated clockwise (or counter clockwise) so that the base zero pin  306  and knob zero pin  327  “bump” one another at which point the “zero” numeral (not shown) etched on the outer circumference of knob assembly  303  aligns with the datum mark (not shown) of turret base assembly  301 . Knob set-screws  322  are then tightened. Knob assembly  303  can then be returned to this “zero” setting at any time to assure the projectile impacts at the same desired point of impact at the same “zeroed” distance. It should be understood that the exemplary embodiment of SBOSSTK  300  could operate in either a clockwise or a counter-clockwise matter. 
         [0052]    To set the “number one” (or first) stop position, stop-ring clamp screw  326  is loosened as are stop ring set screws  324 - 1  through  324 - 6 . The firearm is shot at the distance desired for the first stop location. The knob assembly  303  is rotated counter-clockwise (or clockwise if the system is designed for the opposite direction) so that the “crosshair” reticle coincides with the desired projectile point of impact location at the distance for the first stop location. After the knob is rotated so that the reticle point of aim coincides with the projectile point of impact, protuberance  323 -A ( FIG. 3D ) of stop ring  323 - 1  is engaged with spring-loaded stop plunger  318 - 1 , and stop ring set screw  324 - 1  is tightened. Tightening of the stop ring set screw  324 - 1  prevents further rotation of stop ring  323 - 1 , thereby creating the first rotational stop location. 
         [0053]    The second selectable stop is set by rotating turret knob  321  to adjust the bullet impact with the point of aim on the target at the second desired distance. When the point of impact matches the point of aim at the second desired distance, protuberance  323 -A of stop ring  323 - 2  is engaged with spring-loaded stop plunger  318 - 2 , and the stop-ring set screw  324 - 2  for selectable-stop number  2  is tightened so that stop-ring number  323 - 2  does not rotate. This procedure is repeated for all six stop rings. 
         [0054]    If fewer than six selectable stops are desired, the remaining stop rings are positioned at the full rotation position and their corresponding set screws are tightened. It should be understood that alternative exemplary embodiments can provide less than or greater than six stop-ring set screws for a corresponding number of selectable stops. At the completion of setting the selectable stops, stop-ring clamp screw  326  is tightened to ensure that the stop rings do not rotate during use. 
         [0055]    For field operation, the distance to a target is first determined, then SBSROSSTK  300  is rotated to the (user set) stop corresponding to the target distance. When the stop is encountered there will be a definitive resistance to rotation (i.e., a relatively large tactile click) when the stop lobe of stop ring  323 - 1  interferes with spring-loaded stop plunger  316 - 1 . If the target distance is slightly greater than or slightly less than the distance corresponding to the stop location, SBSROSSTK  300  can be appropriately rotated a few (relatively small) tactile clicks past or back from the stop lobe. Stop lobes can be over ridden by applying additional rotational force to turret knob assembly  303  to allow the stop lobe to depress stop plunger  316 - 1  against its corresponding plunger spring  318 - 1 . 
         [0056]    If SBSROSSTK  300  is used during darkness and viewing the numerical index values (not shown) on the outside circumference of the turret knob  321  is not possible or is difficult, SBSROSSTK  300  can be operated by tactile feel alone. In the situation in which an operator forgets the rotational position of the SBSROSSTK  300  or becomes otherwise confused, the SBSROSSTK  300  can be rotated in a clockwise direction to return to the “zero” position where fixed zero pin  306  and zero pin  326  stop rotation of SBSROSSTK  300 . Once at the “zero” position, the operator can then start from the “zero” position and count selectable stops and clicks to achieve the desired rotational position of SBSROSSTK  300 . 
         [0057]    As SBSROSSTK  300  is rotated in the direction from the fully clockwise position towards the fully counter-clockwise position or in the direction of the fully counter-clockwise position to the fully clockwise position, each operator-selectable stop provides a stop position that can be overridden by applying additional rotational force to turret knob assembly  303 . Between operator-selectable stops, SBSROSSTK  300  can be rotated for fine adjustments. To move beyond an operator-selected stop, additional rotational force must be applied to turret knob assembly  303 . 
         [0058]    Another exemplary embodiment of the subject matter disclosed herein permits a user to insert a multi-stop ring, which has pre-set mechanically stops for the adjustment knob to make a desired adjustment of an optical or power setting without the need to visually observe the value of the adjustment. Thus, optical or power settings made by a user are reliably made or repeated without the need for visual verification regardless of the environmental conditions. 
         [0059]      FIG. 4A  depicts an exploded assembly cross-sectional view of an exemplary embodiment of a Pre-Set Stop Ring Turret Knob (PSSRTK)  400  according to the subject matter disclosed herein.  FIG. 4B  depicts an assembled cross-sectional view of the exemplary embodiment of PSSRTK  400  in a “zeroed” configuration according to the subject matter disclosed herein.  FIG. 4C  shows a top view of the exemplary embodiment of SBPSTK  400  at the first stop configuration according to the subject matter disclosed herein.  FIG. 4D  shows a top view of an exemplary embodiment of a stop ring  423  for the exemplary embodiment of PSSRTK  400  according to the subject matter disclosed herein. 
         [0060]    PSSRTK  400  comprises a turret knob base assembly  401 , an adjustment hub assembly  402  and a turret knob assembly  403 . Turret base assembly  401  comprise a turret base  404 , a plurality of screws  405  and a zero pin  406 . Turret base  404  is fixedly attached in a well-known manner to, for example, a telescopic sight (not shown) or other optical enhancing device (not shown), such as by screws  405 . A zero pin  406  is inserted into an aperture  407  in turret base plate  404 . 
         [0061]    Adjustment hub assembly  402  comprises an adjustment hub  409 , an internal-ring gear  410 , an internal ring gear retainer  411 , and a spade screw  412 . The lower portion of adjustment hub  409  fits inside an aperture  408  that passes through turret base  404 . The lower section of adjustment hub  409  threadably engages an upper portion of spade screw  412 . Spade screw  412  passes through a slot in the body of the telescopic sight (not shown) and mechanically engages in a well-known manner an optical adjustor (not shown) of the telescopic sight. Hub assembly  402  is adjustably positionable in a well-known manner about an axis of rotation (not shown) in order to make adjustments to the scope (not shown). 
         [0062]    Internal Ring Gear  410  fixedly fits around a larger diameter flange  413  of adjustment hub  409  and retains spring-loaded tactile plunger  414  and a spring  415  within flange  413  of adjustment hub  409 . Internal ring gear retainer  411  retains adjustment hub  409 , internal ring gear  410 , and spring-loaded tactile plunger  414  and is held in place by screws  416  (of which only one screw  416  is shown) that extend through holes in a flange  417  of internal ring gear retainer  411  and internal-ring gear  410  to thread into turret base  404 . A spring-loaded stop plunger  418  and a corresponding spring  419  are positioned in a slot  420  in internal ring gear retainer  411 . 
         [0063]    Turret knob assembly  403  comprises a turret knob  421 , two knob-locking set screws  422  (of which only one is shown), a pre-set stop ring  423 , a pre-set stop-ring set screw  424 , a retaining ring  425  to retain pre-set stop ring  423  within the turret knob  421 , a stop-ring clamp screw  426 , and a stop pin  427 . Turret knob assembly  403  is installed over the assembled adjustment hub assembly  402  and retained to the top groove of adjustment hub  409  with knob-locking set screws  422 . 
         [0064]    To “zero” the exemplary embodiment of PSSRTK  400 , the firearm is shot at the desired closest distance to the target with knob set screws  422  tightened. The knob assembly  403  is rotated so that the aiming point of the telescopic sight coincides with the projectile point of aim at the desired “zero” distance. Rotation of turret knob assembly  403  during the “zeroing” process rotates the adjustment hub assembly  402  to extend and/or retract the adjustment spade screw  412  which, in turn, adjusts the internal components of the optical sight (not shown). Knob set screws  422  are then loosened and knob assembly  403  is rotated clockwise (or counter clockwise) so that the base zero pin  406  and knob zero pin  427  “bump” one another at which point the “zero” numeral (not shown) etched on the outer circumference of knob assembly  403  aligns with the datum mark (not shown) of turret base assembly  401 . Knob set-screws  422  are then tightened. Knob assembly  403  can then be returned to this “zero” setting at any time to assure the projectile impacts at the same desired point of impact at the same “zeroed” distance. It should be understood that the exemplary embodiment of PSSRTK  400  could operate in either a clockwise or a counter-clockwise matter. 
         [0065]    Stop pin  430  locations on pre-set stop ring  423  are determined by first “zeroing” the firearm. 
         [0066]    The firearm is then fired with the desired ammunition at the desired distances for any number of stop positions. When knob rotation is determined such that the bullet impact point matches the point of aim at the first desired distance, the index reading from the outside of turret knob  421  is recorded. To determine the location of the second stop pin location, the firearm is again fired with the same ammunition at the desired distance for the second stop position. When knob rotation is determined so that the bullet impact point matches the point of aim at the second desired distance, the index reading from the outside of turret knob  421  is recorded for that distance. The procedure is repeated for each distance for which pre-set stops are desired. 
         [0067]    Pre-set stop ring  423  is then assembled with stop pins  430  inserted into holes corresponding to the rotational position of the turret knob  421  based off of a “zero” position.  FIG. 4D  shows a top view of an exemplary embodiment of a stop ring  423  for the exemplary embodiment of PSSRTK  400  in which stop pins  430  are depicted in selected exemplary locations. Once pre-set stop ring  423  is assembled, it is installed within turret knob assembly  403  by rotating turret knob  421  to a zero position and loosening knob-lock screws  422  and removing turret knob  421  from adjustment hub assembly  402 . Pre-set stop ring  423  is then inserted into the bottom of turret knob  421  and is retained in place by retaining ring  425  and indexed to a “zero” position by stop-ring set screw  424 . Without rotating adjustment hub assembly  402 , turret knob assembly  403  is installed over adjustment hub assembly  402  and aligned to the “zero” position. Knob-lock screws  422  are then tightened to secure turret knob  421  to adjustment hub assembly  402 . 
         [0068]    PSSRTK  400  is operated by first determining the distance to the target and then rotating turret knob  421  to the selected stop corresponding to the target distance. When the stop is encountered, there will be a definitive resistance to rotation (i.e., a relatively large tactile click) when stop pin  430 - 1  of stop ring  423  interferes with spring-loaded stop plunger  418 . If the target distance is slightly greater than or slightly less than the distance corresponding with the stop location, the knob can be appropriately rotated a few tactile clicks past or back from stop pin  430 - 1 . Stop pins  430  can be over ridden by applying additional rotational force to turret knob  421  to allow stop pin  427  to depress the stop plunger  418  against its corresponding plunger spring  419 . 
         [0069]    As PSSRTK  400  is rotated in the direction from the fully clockwise position towards the fully counter-clockwise position or in the direction of the fully counter-clockwise position to the fully clockwise position, each operator-selectable stop provides a stop position that can be overridden by applying additional rotational force to turret knob  421 . Between operator-selectable stops, PSSRTK  400  can be rotated for fine adjustments. To move beyond an operator-selectable stop, additional rotational force must be applied to turret knob  421 . 
         [0070]    If PSSRTK  400  is used during darkness and viewing the numerical index values on the outside circumference of turret knob  421  is not possible or is difficult, PSSRTK  400  can be operated by tactile feel alone. If the rotational position of PSSRTK  400  is forgotten or the operator becomes otherwise confused, PSSRTK  400  can be rotated in a counter-clockwise direction to return to the “zero” position where zero pins  406  and  427  stop rotation of the knob. The operator can then start from a beginning “zero” position and count stops and clicks to achieve the desired knob rotational position. 
         [0071]    Although the foregoing disclosed subject matter has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced that are within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the subject matter disclosed herein is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.