Abstract:
An apparatus is provided for traversing a barrel of a gun and disposing at a select position therein. The apparatus includes a bore-rider assembly and a sight-mount assembly. The bore-rider assembly enters a muzzle of the barrel, slides within a bore of the barrel, and anchors to the select position. The sight-mount assembly projects a line-of-sight from the select position to the muzzle. The bore-rider assembly includes a rod having wedges, first and second bore-riders with proximal and distal ends, a sleeve couple that joins at axial ends the bore-riders in tandem from their proximal ends. Each bore-rider has a rim at the distal end and an extension at the proximal end. The rim has an outer diameter adjustable by expansion. The sleeve couple joins in tandem at each axial end each bore-rider from the proximal end. The rod passes through each bore-rider and the couple. The rod includes first and second wedges that engage their corresponding bore-riders. The rim includes an angularly symmetric plurality of slits therethrough. The slits continuously extend into the extension. The extension includes an axial chamber through which a spring passes through to provide tension for the rod. Cables extend fore and aft of the device and at a slit of the nearest bore-rider and loop around the corresponding extension.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. §119, the benefit of priority from provisional application 61/137,465, with a filing date of Jul. 24, 2008, is claimed for this non-provisional application. 
    
    
     STATEMENT OF GOVERNMENT INTEREST 
     The invention described was made in the performance of official duties by one or more employees of the Department of the Navy, and thus, the invention herein may be manufactured, used or licensed by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 
    
    
     BACKGROUND 
     The invention relates generally to bore sight alignment of a gun. In particular, the invention provides an apparatus using commercially available components with modest modification to enter the muzzle and traverse the bore of the gun. 
     A muzzle bore sight enables precise alignment of a gun onto a specified target by ballistic trajectory. Such tasks are routinely conducted by engineers and gun crews to precisely align the gun. Gun alignment is pivotal to any type of testing being conducted with naval gunnery. Historically, naval guns were sighted by placing a bore telescope at the breech of the gun and aligning the telescope with cross hairs contained at the muzzle. The cross hairs are then aligned on a target within the guns range, allowing for the gun sight to be zeroed in on target. 
     Utilizing the ability to bore sight a gun gives gunners and engineers precise gun alignment with which to evaluate a guns performance. Empirically measuring gun performance, against theoretically engineered specifications, is crucial for proper evaluation of the gun&#39;s design and construction. Conventionally, precision fabrication of any device used to align the gun is of utmost importance, requiring precision machining of any bore sight device used to sight in any gun. 
     SUMMARY 
     Conventional gun-alignment devices yield disadvantages addressed by various exemplary embodiments of the present invention. In particular, various exemplary embodiments provide an apparatus for traversing a barrel of a gun and disposing at a select position therein. The apparatus includes a bore-rider assembly and a sight-mount assembly. These assemblies can optionally be fabricated from commercially available components. 
     In various exemplary embodiments, the bore-rider assembly enters a muzzle of the barrel, slides within a bore of the barrel, and anchors to the select position. The sight-mount assembly projects a line-of-sight from the select position to the muzzle. 
     In various exemplary embodiments, the bore-rider assembly includes a rod having wedges, first and second bore-riders with proximal and distal ends, a sleeve couple that joins at axial ends the bore-riders in tandem from their proximal ends. Each bore-rider has a rim at the distal end and an extension at the proximal end. The rim has an outer diameter adjustable by expansion. The sleeve couple joins in tandem at each axial end each bore-rider from the proximal end. The rod passes through each bore-rider and the couple. The rod includes first and second wedges that engage their corresponding bore-riders. 
     Various exemplary embodiments also provide for the rim to include an angularly symmetric plurality of slits therethrough. The slits continuously extend into the extension. The extension includes an axial chamber through which a spring passes through to provide tension for the rod. Cables extend fore and aft of the device and at a slit of the nearest bore-rider and loop around the corresponding extension. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and various other features and aspects of various exemplary embodiments will be readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, in which like or similar numbers are used throughout, and in which: 
         FIG. 1  is a pair of isometric views of a star gauge alignment carrier; 
         FIGS. 2A and 2B  are a pair of isometric exploded views of a camera bore sight assembly; 
         FIG. 2C  is an elevation view of the camera bore sight assembly; 
         FIG. 3  is an isometric exploded view of a camera clamp assembly; 
         FIG. 4  is an isometric exploded view of a bore rider assembly; 
         FIG. 5  is an elevation and isometric view of a pipe fitting; 
         FIG. 6  is an elevation and isometric view of a tapered nut; 
         FIG. 7  is an isometric view of a wedge shaft; 
         FIG. 8  is an isometric assembly view of the camera bore sight; 
         FIG. 9  is an isometric exploded view of bore sight installation in a gun; and 
         FIG. 10  is an isometric exploded view of an experimental configuration for alignment calibration. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of exemplary embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized, and logical, mechanical, and other changes may be made without departing from the spirit or scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
     Cantilever moment due to the length of the gun barrel introduces an error caused by barrel droop. For a gun bore sighted at the muzzle, the projectile fires higher than alignment indication, resulting in target overshoot. This trajectory raising is caused by the barrel straightening as the gun fires due to gun blast pressure and the projectiles movement through the gun. Placement of a bore sight at the origin of bore (breech end) to negate barrel droop, reduces trajectory error to accurately align the gun on target. 
     Disposing the bore sight at the bore&#39;s origin has conventionally been accomplished with custom-designed precision-tolerance components, thereby raising expenditure. Universalizing an origin of bore sight reduces cost by reducing the number of instruments required for aligning various guns for test firing. Adaptability can include most guns sizes depending on the dimensions of instrument mounted on the bore sight. Cameras and lasers can be readily mounted on the bore sight depending on the test required of the gun. These specifications can be incorporated in various exemplary embodiments of the universalized origin of bore sight using a camera or a laser. 
     Conventional bore sights are of one solid machined component, disposed at the muzzle of the gun. This device employs three extendible contact pins, each pin having first and second positions for engagement and disengagement with the barrel interior surface. Depending on the model, each point of contact is of hardened steel or anodized aluminum allowing for smooth motion over the rifling of the barrel. 
     Several conventional techniques are employed to provide a concentric fit between the barrel and bore riders, while maintaining mobility in the bore. One method utilizes a spring-loaded contact pin at each support position, which creates an interference fit aligning the bore riders concentrically within the barrel. This design is complimented by its adaptability to changes in the inner bore diameter due to barrel fowling or erosion. Other designs that do not utilize the spring contact point require precise machining and tight tolerances to obtain a concentric fit. Such tight tolerance complicates insertion of the bore sight and often requires lubricants for installation. 
       FIG. 1  shows a pair of isometric views of a conventional star gauge alignment carrier. The star gauge assembly depicts the components for measuring inner bore diameter. The left view  100  shows a bore segment  110  along the axial centerline of a 57 mm barrel. A center star support  120  concentric to the centerline is disposed within the segment  110  and contains a triplet of equal-distant contact pins  130 , shown disengaged from the inner diameter of the segment  110 . A tapered rod  140  having cylindrical proximal and conical distal ends is disposed along the centerline. As the rod  140  translates towards the support  120 , the distal end engages the pins  130  extending them radially outward, as shown in the right view  150 . Moving the rod  140  linearly forward forces the pins to the exact inner bore diameter of a 57 mm barrel, thereby enabling alignment. 
     Another conventional configuration uses two positions of contact but incorporates six contact pins at each position. These bore-riders include metal tongs forming a tapered conical shape. The tongs allow for equal displacement when inserted into a barrel maintain concentricity within the barrel regardless of inner diameter. 
     Various types of bore sights use either an optic eye piece or laser for target alignment. An example of an optic eye piece would be a telescope with 90°-view attached to the bore rider. This enables an operator to view the desired target from the muzzle and align the gun accordingly. Replacing the telescope with a laser enables targeting by positioning the reflection dot on the target, which can accelerate gun target alignment. Camera bore sights use lenses and sophisticated closed couple device cameras mounted in line with the telescope relaying video back to personnel that control gun movement. This technique enables precise target tracking viewed from within the barrel. 
     Incorporating the previously cited above features into a universal bore sight provides the rationale for the configuration represented in various exemplary embodiments. Such a bore sight device can preferably be designed and fabricated for adaptation to multiple bore sizes. This device preferably also contain features to mount a camera and lens capable of viewing the target range of the gun being sighted, or alternatively to mount a laser for a secondary measure to sight the gun on target. The universal bore sight is capable of being disposed in any position along the axis of the barrel, from the muzzle to the origin of the bore. 
     Researching and examining several preexisting bore sight designs led to the option of adapting the star gauge to act as bore-riders, which would center within the bore of any gun placed in. The star gauge represents a device used to precisely measure the inner bore diameter of guns, ranging from 3-inch to 16-inch with accuracy to a ten-thousandth of inch. The gauge operates by inserting a head socket, attached to a connecting rod to a desired depth within the barrel. Upon reaching this depth, the connecting rod pushes a conical wedge into a head socket extruding out measuring points equally. These measuring points then contact the lands of the barrel and an inner bore diameter can then be measured. Assuming self-centering during this process, the star gauge provides a useful mechanism for aligning either a camera or laser within the bore of a gun. By varying the lengths of contact pins, the star gauge could be easily adaptable to multiple guns. 
     A pair of coupled star gauges can be combined with the ability to expand simultaneously. The camera or laser can be attached to the star gauges to produce a bore sight capable of centering itself within the bore of a gun. Due to the reliability placed on the star gauges ability to accurately measure inner bore diameters to within ten-thousandths of an inch, this design was considered to be precise and a feasible design. This particular configuration is discarded for these purposes due to design complicity and resultant time needed for manufacture. 
     Various exemplary embodiments provide Step-Collet Bore Riders with a Couple. Artisans of ordinary skill will recognize that a collet constitutes a holding device—specifically, a subtype of chuck—that forms a collar around the object to be held and exerts a strong clamping force on the object when tightened via a tapered outer collar to hold a workpiece or a tool. Generally, a collet chuck, considered as a unit, includes a tapered receiving sleeve (often integral with the machine spindle), the collet proper (usually composed of spring steel), which is inserted into the receiving sleeve, and (often) a cap that screws over the collet, clamping it via another taper. 
     Typically in shop-floor terminology, the terms “collet” and “chuck” are used in contradistinction; users describe holding a workpiece or tool with either a collet or a chuck. This usage refers to the same distinction as does a collet chuck or alternatively another type of chuck (scroll chuck, independent-jaw chuck, etc.). The terms collet and chuck are substantially interchangeable. The principle difference involves conceiving the overall chain of connection between the machine spindle and the item being attached thereto (workpiece or tool). Generally, the overall system of holding constitutes a chuck, but practically, the receiving sleeve for a collet is often integral with the machine spindle, and from the point of view of naming the parts that are added on to the spindle, they are either a collet (with or without a cap) or a chuck (such as a scroll chuck). 
     Components from various exemplary embodiments of the universal bore sight can be examined at  FIGS. 2A and 2B  in isometric exploded views  200 .  FIG. 2A  shows the exploded view looking somewhat aft from the fore.  FIG. 2B  shows the exploded view looking somewhat forward from the rear. A camera assembly  210  at the fore includes a 100 mm lens  215 , a 2× magnification lens  220 , an XC-555 camera  225 . A camera-mount module assembly  230  is disposed behind the camera assembly  210 , including a securing bolt  235 , a washer  240  and a camera tube  250  with several set screws  255  arranged in cruciform pattern along the exterior of the tube  250 . Artisans of ordinary skill will recognize that the camera  225  can be replaced with a laser-sight without departing from the scope of the invention. 
     The bore sight assembly also includes a wedge rod  260 , a fore bore-rider  265 , a rider coupler  270 , an aft bore-rider  275 , a helical spring  280 , a spring pin  285  and a tapered wedge nut  290 .  FIG. 2C  shows an elevation cross-sectional view of a universal bore sight assembly  295 . The camera  225  inserts into the tube  250 , which attaches to the rod  260  passing through the bore-riders  265 ,  275  and the couple  270 . The nut  290  attaches to an aft end of the rod  260 . 
       FIG. 3  shows an exploded isometric view  300  of the module assembly  230 , which primarily includes the wedge rod  260  and the camera tube  250  aligned to each other and to the bore-riders  265 ,  275 . The tube  250  includes an insertion cavity with an inner surface  310  to receive the 2× lens  220 , an annular landing  320  initiating a chamber having an inner surface  330  to receive the camera  225 . The tube  250  includes orifices  340  into which the set screws  255  can be inserted to secure the camera  225 . 
     The rod  260  includes a fore button  350  with a truncated conical wedge or flare  360  that extends beyond the diameter of the shaft  370 . The rod  260  includes an orifice  380  into the cylindrical exterior through which the pin  380  can be inserted. The orifice is disposed near an aft end  390  opposite to the fore button  350 . The aft end  390  receives the nut  290  to inhibit axial translation. 
       FIG. 4  shows an exploded isometric view  400  of the pair of collets concentrically connected by the couple  270 , to form bore-riders  265 ,  275  upon assembly for the bore sight. Each collet includes an outer rim  410  at its proximal end, bounded axially by an aft chamfer  420  and a fore chamfer  425 . An axial channel  430  extends through the rim  410  to receive the rod  260 . The rims  410  represent the portions of the bore-riders  265 ,  275  that engage the barrel&#39;s bore. 
     A triplet of proximal slits  440  divides the rim  410  into equal angular portions to form 120° angular separation. The proximal slits  440  are continuous with distal slits  445  on an extension  450  that engages the couple  270  at the collet&#39;s distal end. The distal slits  445  linearly diminish their depths with increasing distance from the rim  410 . The extension  450  includes male screw threads  455  along the outer extent at the distal end and a cavity having an inner surface  460  with a diameter not less than that of the channel  430 . 
     The couple  270  includes an inner surface  470  with female screw threads  475  to receive the counterpart male screw threads  455  of the collet&#39;s extension  450 . The couple  270  also includes a landing  480  for the collet&#39;s distal end and an inner annular chamber  490  for the rod  260 .  FIG. 5  illustrates an isometric view  500  and an elevation cross-section view  510  of the couple  270 , which has axial ends  520  defined by a cylindrical rim  530 . 
       FIG. 6  illustrates an isometric view  600  and an elevation cross-section view  610  of the nut  290 . The tapered outer surface  620  is defined by a frustum, whereas the inner surface  630  is cylindrical. The nut&#39;s outer surface diminishes from its fore end  640  towards its aft end  650  by an angle slope of 95° from vertical rendering a radial 5° wedge from aft to fore that engages the channel  430  of the aft bore-rider  275 . 
       FIG. 7  illustrates an isometric view  700  of the rod  260 . The fore button  350  includes an outer rim extent  710 , an inner bore  720  and screw threads  730  to receive the screw  240 . The flare  360 , tandem to and terminating at the button  350 , includes a radial 5° wedge from aft to fore so that its ridge engages the channel  430  of the fore bore-rider  265 , and an annular land at the forward end of the flare  360  abuts against the aft surface of the tube  250 . 
     The bore-riders  265  and  275  employ collets as a practical solution to the design criteria, after consideration of several alternate bore sight designs. Collets are used in a metal lathe to hold irregularly sized objects while being turned in the lathe. Typically, these are made from relatively soft metal allowing for them to be machined fitting the desired size of the irregularly dimensioned object. The collets also have the unique ability to clasp objects by the partial separation into three sections. This allows the collets outer diameter to increase or decrease to some limited amount. This feature enables the collet&#39;s rim to match any diameter of the bore, while being moved throughout the gun. 
     By coupling two collets in tandem, end to end, provides the bore-riders sufficient support for concentric fit in the gun barrel. Also, staying within the dimensional boundary conditions of the straightness gauge, ensures the bore-riders fit throughout the bore length. This design takes advantage of cost off the shelf items, significantly reducing the cost of fabricating the exemplary designs. Commercially available collets can be purchased in a variety of sizes, enabling the device to be adaptable to multiple bore sizes. 
     Collets can be purchased in a variety of outer diameter sizes, allowing them to fit most guns, which gives the bore sight adaptability. The collets incorporated for the bore-riders  265 ,  275  are standard items from the auto industry at about $37 apiece, and as originally purchased have rims  410  with 3-inch outer diameter. The exemplary bore-riders  265 ,  275  were obtained by modification of Lyndex 550-003 step collets. These can be obtained from Lyndex-Nikken, Inc., 1468 Armour Blvd., Mundelein, Ill. 60060, Tel: 800-543-6237, Fax: 847-367-4815. The original outer diameter of 3.00-inch for the rim  410  was machined down to 2.983-inch for the 76 mm bore to be tested. Machining of the collets was accomplished by a lathe using a ½-inch dowel for insertion in the channel  430  to inhibit rim deflection. 
     The distal slits  445  terminate prior to farthest extent of the threads  455 , which are set to 1.238-inch male. The coupling  270  is configured to correspond with female threads  475 . The coupling  270  includes an external rim  530  having an outer diameter, a distal inner diameter (both ends) terminating in the flat shoulder  480  perpendicular to longitudinal axis, and the annular chamber  490  of ½-inch diameter to enable the rod  260  to slide through. The rod  260  terminates at the fore with the flare  360  and the button protrusion  350 . The rod  260  terminates at the aft end with the lateral orifice  380  to receive the pin  385  (to adjust spring tension) and an elongated threaded extension for the nut  290  with a radial 5° wedge. The nut  290  unscrews to remove the rod  260  from the assembly of bore-riders  265 ,  275  and couple  270 . 
       FIG. 8  illustrates an isometric view  800  of the bore sight assembly  395  in cooperation with cables to present an assembly package  810  to slide within the bore. The package  810  includes a bore-sight assembly  815  with the bore-riders  265 ,  275  connected to the couple  270 . A front control cable  820  extends forward of the lens  215  towards insertion into a slit  445  of the fore bore-rider  265 . Similarly, a camera module cable  830  also extends forward of the lens  215 . The camera module cable  830  splits adjacent the camera tube  250  at a fork  835  into two slits  440  and around the flare  360  of the rod  260 . The front control cable  820  passes through the slit  445  of the fore bore-rider  265  and splits behind the rim  410  to wrap around the extension  450  by cable loop portions  850  and  855 . 
     Loop cable portions  860  and  865  join together through a slit  445  of the aft bore-rider  275  extending rearward to a rear control cable  870 . The front cable  820  attaches to the front bore-rider  265  in a similar manner the rear cable  870  loops around the aft bore-rider  275 . By tensile forces  880  pulling on the cables  820 ,  830 ,  870 , the bore-riders  265 ,  275  disengage from the rod  260  for loosening against the bore to enable retrieval of the package  810  from the barrel  920 . The front and rear control cables  820  and  870  loop around their respective bore-riders  265  and  275  through one of three slits  445 . Such looping ensures lack of interference between the cables and their corresponding bore-riders during positioning the assembly package  810  in the gun bore. 
       FIG. 9  depicts an isometric sectional view  900  of a gun turret  910  with the bore sight assembly package  810  with cables. A gun within the turret  910  includes a barrel  920  having an origin  930  and a muzzle  940 . The assembly package  810  is disposed within the barrel  920  with the cables  820 ,  830  extending beyond the muzzle  940  and terminating with respective muzzle cable handles  950 ,  960 . The rear cable  870  extends through the origin  930  beyond a breech  970  terminating with a breech cable handle  980 . 
     The rear cable  870  traverses the barrel  920  through the muzzle  940  and exits the gun through the breech  970 , terminating at the handle  980 . The front cable  820  follows the assembly package  810  through the barrel  920 , and terminates at the handle  950 . An operator at the breech  970  of the gun controls the rear cable  870 , enabling the operator to pull the assembly package  810  through the gun bore during installation of the assembly package  810  by pulling the handle  980 , and subsequently apply tensile force  880  to the cables  830  and  870  when removing the assembly package  810 . 
     The tensile force  880  applied to the rear cable  870  can be used to secure the bore-rider assembly  815  in position from the handle  980 , while the front cable  820  applies an opposite tensile force  880  to the module assembly  230  from the handle  950 , which dislodges the aft-facing wedges from their respective channels  430  of the corresponding bore-riders  265 ,  275 . Once dislodged, the rims  410  of the bore-riders  265 ,  275  relieve to their initial diameter and for extraction of the assembly package  810  from the gun bore. The front and module cables  820 ,  830  loop around aft of the module assembly  230 , following the assembly package  810  into the gun bore during installation. 
     An operator at the muzzle  940  can subsequently pull the assembly package  810  out of the barrel  920 . Alternatively, the operator can disengage the bore riders  265 ,  275  by pulling the module assembly  230  away from the bore-rider assembly  815 , while maintaining the assembly package  810  within the barrel  920 . The camera module cable  830  also follows the assembly package  810  through the muzzle  940  as a precautionary measure to enable additional force being applied for removing the assembly package  810  from the barrel  920 . 
     Pulling the breech cable handle  980  rearward away from the breech  970 , enables the assembly package  810  to traverse the bore from the muzzle  940  to the origin  930  of gun. Pulling either muzzle cable handle  960  or  950  forward away from the muzzle  940  (from forward of the gun) enables the assembly package  810  to traverse the bore towards the gun&#39;s muzzle  940 . Engaging the bore-rider rims  410  against the bore requires the breech cable handle  980  be held in tension. 
     The muzzle cable handle  960  pulls until module assembly  230  separates from the bore-rider assembly  815 . The spring  280  contacting the center of the inner shoulder  480  of the couple  270  inhibits further motion of the muzzle cable handle  960 , which releases in response to achieve the spring-loaded position, thereby causing the module assembly  230  to spring back into the bore-rider assembly  815 . This action forces the flare  360  and the nut  290  against the channels  430 , thereby radially expanding the rims  410  to conform to and fit against the bore. 
     The bore-rider assembly  815  secures and aligns the assembly package  810  within the barrel  920  by expanding their outer rims  410  until tightly pressed radially against the bore. This is accomplished by pressing the bore-riders  265  and  275  axially by the flare  360  and nut  290 , respectively at the fore and aft of the rod  260 . The nut  290  secures to the aft end of the rod  260  by a threaded connection, thereby enabling the nut  290  to self-align along the longitudinal axis of the bore sight as the male screw threads  455  of the aft bore rider  275  rotates into female screw threads  475  of the couple  270 . This process ensures that the both the flare  360  on the rod  260  and the nut  290  together contact the corresponding channels  430  on their respective bore-riders  265 ,  275  concurrently. Maintaining simultaneous contact with bore-riders  265 ,  275  ensures equal expansion and concentric fit within the bore of the barrel  920 . 
     Removal of the secured bore-riders  265 ,  275  from the channel  430 , requires the forces applied by the nut  290  and the flare  360  be displaced from their interference-fit positions merely by pulling the rod  260  out away from the bore-rider assembly  815 . Within the barrel  920 , this task can be accomplished with the two control cables  820  and  870 , the rear cable  870  looped around the aft bore-rider  275  and the forward cable  820  looped around the fore bore-rider  265  past the aft portion of the module assembly  230 . 
     The rear cable  870  attached to bore-rider  275  provides a resistive force as the module assembly  230  pulls away from the bore-rider assembly  815 , therefore displacing the rod  260 , relieving pressure against the bore-rider assembly  815 . Upon release, the outer rims  410  of the bore-riders  265 ,  275  return to their original diameter (neutral state) to provide sufficient clearance for smooth removal of the bore sight assembly  810  from the bore of the gun barrel  920 . The nut  290  secures to the rod  260  with a 0.375-16 UNC -2B- THRU - THREAD  readily being screwed on or off. 
     The muzzle terminals of entry for a bore sight device determines facility for traversing through the bore. Depending on the gun design, entering from the breech  970  requires only a short distance to be traveled before final position is reached at the origin  930  of bore. There, the bore-riders  265 ,  275  only encounter a small portion of rifling; extremely tight tolerances may be used without the possibility of the device jamming due to fowling of the barrel  920  from fired rounds. However, installing the bore-sight assembly  810  from the breech  970  requires extruding video and power cables through the complicated machinery used to operate the gun. In many cases, to access the breech  970  of a gun is impractical for operational applications. 
     Therefore, considering the design of the universal bore sight, insertion from the muzzle  940  is the most accessible choice of entry, involving less time to integrate the device within the origin  930  of bore. However, inner diameter changes along the length of the barrel  920 , which introduces altering tight tolerance for the bore-rider through the inconsistencies of the bore. Although, moving the bore sight device through the muzzle  940  may be difficult, this represents the only practical point of entry to the origin  930  of bore. 
     Due to the accessibility of 76 mm barrels, an analysis of bore diameters was accomplished using data obtained from the star gauge, showing that a newly manufactured barrel changes one-thousandths of an inch from the muzzle  940  to the origin  930  of bore. In addition, naval regulations permit some increase in bore diameter at the muzzle  940 . From these data, the bore-riders  265 ,  275  can be adapted to a variety of bore diameters to ensure concentricity and accurate gun alignment. 
     Placement of the bore sight at the origin  930  of bore depends on whether barrel droop extent suffices to introduce unacceptable error into tests. The error occurs under conditions of the bore sight mounted at the muzzle aligns the gun lower than the gun&#39;s actual aim point. A straightness gauge can be used to ensure that barrel droop remains within appropriate limits. The straightness gauge used for a 76 mm gun has the diameter of 75.92±0.03 mm, length of 330.2 mm, and straightness of ±0.03 mm. The bore-riders  265 ,  275  are designed within those limits to ensure uninterrupted movement of the bore sight throughout the bore of the 76 mm gun. 
     The flare  360  provides the compression to slam against the assembly to expand the rims  410  and wedge them in the barrel  920  of the gun being aligned. The flare  360  contacts the fore bore-rider  265 . To set the assembly package  810  into position, the rod  260  is pulled forward and released —the spring  280  provides the tension force to ram the rod  260  rearward so that the flare  360  engages the edge of the channel  430  of the fore bore-rider  265 . The force is provided by the cables  820 ,  830  connected to fore bore-rider  265  behind the module assembly  230 . The rear cable  870  prevents the assembly package  810  from being pulled out of the bore, while the fore cable  820  provides tensile force. Upon relieving tensile force on the front cable  820 , the rod  260  springs back into bore-rider assembly  815 . 
     The exemplary couple  270  secures the bore-riders  265 ,  275  in tandem. Due to the unique threads on select exemplary collets (as modified for the bore-riders), a specialized coupling  270  was designed and machined. The exemplary couple  270  incorporates tight 1.238″×20 right-hand (RH) internal threads and a perpendicular resting shoulder. These qualities ensured a tight and true alignment of the bore-riders  265 ,  275  as they are joined by the couple  270  to form the bore-rider assembly  815 . A precise ½-inch hole for the annular chamber  490  drilled through the couple  270  provides secondary support for the rod  260 , ensuring precise alignment for attachment to the module assembly  230 . 
     The exemplary rod  260  at ½-inch diameter extends through the half-inch channels  430  in both rims  410  of the bore-riders  265 ,  275  and the annular chamber  490  of the coupling  270 . The rod  260  has tapered wedges on each end: the flare  360  fixed at the fore and the detachable nut  290  at the rear. Upon translation, these wedges concurrently contact the respective collets  265 ,  275  expanding the outer diameter of their rims  410 . 
     The exemplary rod  260  includes a ⅜-inch threaded end that facilitates precise positioning of the nut  290  to adjust its axial position on the rod  260 . The rod  260  can be precisely machined to ensure perfect concentric fit and alignment between the flare  360  and module assembly  230 . The fore button  350  has an axial ¼-inch hole  720  tapped in the tip  710  allowing for the rod  260  and module assembly  230  to be bolted together. A ⅛-inch hole can be drilled through the aft end of the rod  260  just ahead of the threads, enabling insertion of the spring pin  285 , which secures the spring  280  that applies constant force on the rod  260  to maintain integration within the bore-rider assembly  815 . 
     The exemplary module assembly  230  includes an aluminum tube  250  with a length of six-and-one-half inches and an outer diameter of two inches. The lenses employed for this bore sight enable the module assembly  230  to contain only the camera  225  and a partial lip of the lens  215 . The module assembly  230  attaches to the wedge rod  260  through a concentric ½-inch hole. To ensure precise alignment, the fit between both parts can be an interference fit, held together by the bolt  235  and washer  240 . To ensure precise alignment of the camera and bore-riders, eight set screws  255  are disposed around the camera tube  250 ; enabling fine calibration of the optical assembly. 
     Camera and laser analysis have been employed to select the most appropriate sensor size for providing a clear view of distant targets. Research indicated that a charge-couple device (CCD) camera provided the best video signal due to pixel&#39;s charge conversion to voltage, which can be buffered and transferred through a single node as an analog signal. Another aspect of the camera  225  to be determined was the sensing area and number of pixels needed for a quality picture. The smallest camera currently available with standard sensing and pixel specifications yielded a sensing area of 6.4 mm×4.8 mm and pixels 768×494. Selection led to the Sony XC-555 Color CCD camera being the preferred available and cost-effective option. 
     The desired field of view necessary for current range testing required the camera  225  to view a target at 300 yards with considerable accuracy. To obtain the desired field-of-view, camera characteristics include accounting for pixel count and sensing area. Utilizing a 100 mm lens and a 2× fixed focal length lens extender that increases the lens power to 200 mm provides a field of view of 31-feet×31-feet. This enables the camera  225  adequate view power to observe an object ¾-inch×1.5-inch in size, which satisfies the desired field-of-view for the camera bore sight. Consequently, the outer diameter of the 100 mm lens being used is 1.927-inch, so the smallest muzzle the bore sight can be inserted into corresponds to a 57 mm gun. This gives the bore sight an adaptable range of 57 mm to a 155 mm gun barrel range. However, this range could be lowered depending on the outer diameter of the optic or laser being used. 
     With many lasers available on the market, selecting a preference involves small size with ability to be mounted concentrically. A tube-mounted laser facilitates calibration for mounting on a bore sight device. Helium-neon and diode lasers are the prominent choice because of their concentric placement within a tube. Due to extended range operations the laser may be preferred, necessitating a beam expander on the laser. The specific type of beam expander may be a Galilean beam expander using a Plano-Concave lens and an achromatic lens to collimate the beam for reducing the laser spot size at a given distance. 
     Depending on the type, both gas and diode laser presumably perform comparably in range and accuracy. With the helium-neon laser averaging ±1.0 mrad parallel to outer cylinder and a beam divergence of ±1.2 mrad. The diode laser averaging beam versus housing alignment &gt;3 mrad and a beam divergence of &gt;3 mrad. Although gas lasers may perform slightly better than diode lasers, there are some draw backs with their use in bore sight application. Gas lasers are considerably larger than the diode lasers, averaging around ten-inches in length by 1.74-inch in diameter. A gas laser&#39;s operational life span may also be considerably less than that of a diode lasers; averaging around 40,000 hours compared to a diode&#39;s life of 50 hours to 100,000 hours of operation. Incorporating high-performance structured light laser diode modules represents the preferred selection for adapting a laser to any bore sight device. 
     The camera bore sight assembly package  810  includes two major sections: the aft portion including the bore-riders and the fore portion that houses the sight-mount. The aft portion with the bore-rider assembly  815  includes bore-riders  265 ,  275  that are assembled by joining two collets end-to-end in tandem with a steel couple  270 . The fore portion consists of the module assembly  230  and the camera assembly  210 . The two sections join by the center wedge rod  260  bolted to the module assembly  230 . 
     To ensure both sections remain intact, a spring  280  is disposed within the extensions  450  of collets to secure the rod  260  to the coupling  270 . The joining of both sections by the spring  280  provides a force to pull the module assembly  230  into the fore bore-rider  265 . The spring  280  engages the wedges as the flare  360  and the nut  290  in corresponding channels  230  of their respective bore-riders  265 ,  275 . Upon completion of the assembly package  810 , the bore sight is ready for integration within the desired gun. 
     Integration process of the bore sight assembly package  810  to within the origin  930  of bore employs cables  820 ,  830 ,  870  of 3/16-inch diameter that span the length of the gun barrel  920 . The process of integration begins by pulling the rear cable  870  through the barrel  920  by the retraction of an extendable tape measure attached to the rear handle  980 . The rear cable  870  can then be secured around the aft bore-rider  275 , with which to pull the assembly package  810  through the barrel  920 . The front cable  820  attaches to the front handle  950  and around the fore bore-rider  265 , providing bidirectional control in the barrel  920  for the bore sight. The module cable  830  can be wrapped around the module assembly  230  at the flare  360 , enabling control to withdraw the bore-rider assembly  815  from the barrel  920 . 
     To secure the bore sight within the barrel  920 , the assembly package  810  is pulled to the origin  930  of bore and held in place by the cables  820 ,  830 ,  870 . The camera module cable  830  is then pulled, separating the module assembly  230  from the bore-riders  265 ,  275  by several inches. The module cable  830  is then released, causing the module assembly  230  to spring back lodging the wedges (flare  360  and nut  290 ) into the channels  430  by the rod  260  snapping back due to the spring  280 . This fixes the bore sight within the barrel  920 . In the secure configuration, the gun can either be sighted in or used for target tracking. 
     Removing the bore sight can be accomplished by pulling the camera module cable  830 , which separates the wedges from the channels  430 , relieving their force. This collapses the rims  410  to reduce their relaxed outer diameters, returning mobility of the assembly package  810  within the barrel  920 . In the release configuration, the bore sight can be readily removed from the barrel  920 , completing the integration process. 
     Hardware associated with camera and laser can be translated with the bore sight along the barrel  920  from the muzzle  940  during installation. Electrical power and video-signal cables can extend from the point of entry at the muzzle  940  to the bore sight. Cables can be attached to exterior surfaces of the gun, enabling the gun to slue about without concern of damaging any connection that may exist between video monitors and bore sight. 
       FIG. 10  is an isometric view  1000  of an alignment calibration exercise for determining error associated with the bore-riders and bore of a 76 mm gun barrel  1010  on a support stand  1020 . A mirror mount  1030  at one end of the gun barrel  1010  secures a mirror  1040 . A subcollimator  1050  is mounted on a tripod  1060  with a line-of-sight to the mirror  1040  opposite. 
     Testing was conducted in order to determine the alignment of the bore-riders within the bore of the 76 mm gun. This involved mounting the mirror  1040  on the front face of the bore-riders and measuring concentricity with the autocollimator  1050 , which constitutes an optical instrument used to measure angles by projecting a reticle on a surface of the mirror  1040  and measuring the displacement of the return image. 
     The experimental setup included the 76 mm barrel  1010 , mirror mount  1030 , mirror  1040 , bore riders, and autocollimator  1050 . The bore-riders were disposed within the muzzle of the 76 mm barrel  1010 , the mirror  1040  mounted on the front face of the bore-riders with a screw, and then aligning the autocollimator&#39;s image on the mirror  1040 . After alignment, the return image was viewable from the optical objective on the rear side of the autocollimator  1050 . To determine alignment, the bore-riders remained not engaged, leaving two-thousandths of an inch clearance between the bore-riders and the bore. The clearance permitted free rotation, which revealed an area-of-run out between the two reticles. Further testing was conducted by sliding the bore-riders down the entire length of the 76 mm gun barrel  1010  to identify any error that might occur throughout the barrel. 
     Test results indicated a one-arc-minute displacement, as the bore-riders were being rotated, and no displacement as the bore-riders were translated (without rotation) throughout the bore length. This indicates that for the gun to be sighted in on a target at 300 yards, there would be a three-inch misalignment on the target. However, the displacement is expected to significantly diminish upon engagement of the bore-riders, which centers them within the bore. Further testing may include mounting the camera in the bore sight and measuring alignment with a similar process as mentioned previously. 
     Various embodiments described configure the initially fabricated bore sight for use with a camera. However, future adaptabilities include mounting a laser in lieu of the camera for quick target alignment. Other prospects include mounting a wide-angle lens on the camera to enable the bore sight to be transformed into a bore scope. 
     This would provide gun crews the ability to quickly inspect the bore for any indications of wear on the lands or chrome lining. The bore sight can also be adapted to smaller guns depending on the size of lens needed for target alignment. Artisans of ordinary skill will recognize that these represent only exemplary embodiments for modifications, and that others can be envisioned without departing from the scope of the claims to enable the bore sight adaptability to various guns by precise and interchangeable bore riders. 
     Various exemplary embodiments provide an adaptable bore sight capable of fitting at any linear position within multiple sized gun bores. The device has the capability of mounting either a laser or camera for target alignment. The incentive for such a design developed from the error introduced in conventional muzzle-mounted bore sights. Due to barrel droop, muzzle mounted bore sights align the gun to fire higher than intended. Disposal of the bore sight at the origin of bore rather than the muzzle reduces error associated with barrel droop, thereby drastically improving gun alignment on targets. 
     While certain features of the embodiments of the invention have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the embodiments.