Patent Publication Number: US-4321737-A

Title: Gunsmith&#39;s tool

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to gunsmith&#39;s tools, and more particularly relates to a tool by which a gunsmith may more precisely and efficiently perform surface-finishing work upon the muzzle of a shotgun or similar firearm. 
     A substantial part of the average gunsmith&#39;s business activity is devoted to shortening the barrels of firearms brought to him by customers. In the case of firearms of the shotgun type, this is necessary when the customer desires to change the &#34;choke&#34; of his gun, either merely by reducing the barrel length or by the addition of a POLYCHOKE® or similar muzzle device to it. In both of the foregoing cases the gunsmith must first cut off a portion of the muzzle of the gun&#39;s barrel, which step is customarily performed by use of a lathe or the like, and then must hand-finish the cut end surface of the muzzle for the purpose of smoothing the same and of producing a &#34;square&#34; (i.e., perpendicular) relationship between it and the barrel&#39;s axis. The finishing may at times also include some further shortening of the barrel to bring it to precisely the desired reduced length. When the foregoing muzzle-finishing work is done by the use of a conventional metal-cutting file, as is now the customary practice, it is exceedingly laborious and time-consuming. It requires considerable alternate filing and gauging, and even then frequently fails to produce a precisely &#34;square&#34; muzzle surface. 
     DESCRIPTION OF THE PRIOR ART 
     While not pertaining to tools used by gunsmiths for the finishing of gun muzzles, the following U. S. patents disclose tools usable in association with generally cylindrical work of diverse types: U.S. Pat. Nos. 3,942,289, 3,870,429, 3,532,010, 2,598,765, 1,988,411, 1,946,416, 1,839,391, 1,715,546 and 992,437. 
     SUMMARY OF THE INVENTION 
     The gunsmith&#39;s tool of the present invention comprises an elongate shank that is rotatable about its central axis by means upon one of its end portions. Upon its opposite end portion the shank has a generally cylindrical guide member closely receivable within the barrel of a firearm whose muzzle is to be finished. File means, which preferably is in the form of a disc-like member having filing teeth upon its bottom surface, is connected to and rotatable with a medial portion of the shank of the tool and projects radially outwardly therefrom into overlying engagement with the muzzle end surfaces of a gun barrel within which the guide member is received. The guide member insures that the teeth upon the disc-like member &#34;square&#34; the muzzle end surfaces, as well as otherwise finish the same, when the shank of the tool is rotated. 
     In a preferred embodiment both the file means and the guide member of the tool are releasably secured to its shank, and the radial projection of the file means from the shank is sufficiently great for it to simultaneously overlie and finish the muzzle end surfaces of both barrels of a double-barreled gun. 
    
    
     DESCRIPTION OF THE DRAWING 
     Other features and benefits of the invention will be apparent from the following description of an illustrative embodiment thereof, which should be read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a partially-exploded side elevational view of a gunsmith&#39;s tool in accordance with the invention, one component of the tool being partially broken away; 
     FIG. 2 is a view taken approximately along the line 2--2 of FIG. 1 and showing components of the tool, one of which is partially broken away, in bottom plan and in horizontal cross-section; 
     FIG. 3 is a fragmentary elevational view showing components of the tool in operative association with the muzzle of the barrel of a shotgun or similar firearm, the barrel being partially broken away; and 
     FIG. 4 is a fragmentary elevational view similar to FIG. 3 and showing the same components of the tool in association with the muzzle of a double-barreled shotgun or similar firearm. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1 of the drawings the numeral 10 designates a gunsmith&#39;s tool having an elongate shank 12 adapted to be rotated about its longitudinal axis by drive means upon its upper end portion. The drive means illustratively comprises a manually operable crank-like member 14 formed integrally with shank 12 and having handle members 16, 18 that are grasped and manipulated, in a well known manner, by a person using the tool. A generally cylindrical &#34;pilot&#34; or guide member 20, preferably and illustratively formed of nylon or similar smooth and wear-resistant plastic material, is releasably mounted upon and in concentric encircling relationship with the lower end portion of shank 12. More specifically, the lower end portion of shank 12 is closely received within and abuts the bottom of a blind bore 22 extending centrally of guide member 20 and opening from its upper end. A smaller diameter bore extends centrally through the bottom of guide member 20 and is aligned with a threaded bore within the bottom of shank 12. The aforesaid bores receive a screw-type fastener 24 which, when tightened, prevents displacement of member 20 from shank 12. Member 20 is adapted to be closely and concentrically received within the muzzle end portion of the barrel of a firearm, and its outer diameter therefore is only slightly less than the inner diameter of such barrel portion. Additional guide members, not shown in the drawings but corresponding to the illustrated member 20 except for their having differing outer diameters, preferably are provided so that the one of appropriate corresponding size may be mounted upon shank 12 when tool 10 is used in association with a firearm having a different muzzle diameter. Substitution of another guide member for member 20 may be easily accomplished simply by removing fastener 24, sliding member 20 from shank 12, and then mounting the substitute guide member upon the shank in the same manner. 
     Filing means, illustratively in the form of a flat disc-like member 26 having file teeth 28 upon substantially all of its undersurface, extends in concentric relationship to and projects radially outwardly from a medial portion of shank 12. Member 26 is releasably connected to shank 12, for rotation in unison with it, by mounting means that includes a disc-like backing plate 30 fixedly and concentrically secured in any suitable manner upon the aforesaid medial portion of shank 12. A plurality of screw-type fasteners 32 extend through respective ones of a corresponding plurality of bores provided within plate 30 and into aligned threaded bores provided within the upper part of member 26. When fasteners 32 are tightened, the upper surface of member 26 is firmly engaged and fully &#34;backed&#34; by the equal-diameter bottom surface of plate 30. This enables member 26, which usually will be formed of somewhat brittle steel, to better withstand the vertical stresses imposed upon it during use of tool 10. The releasable mounting of member 26 permits the substitution for it of another disc member which may be identical to member 26 or which may have coarser or finer file teeth upon its bottom surface. Such substitution, if desired, may be readily effected following disengagement of fasteners 32 and removal of guide member 20 from shank 12. 
     The bottom surface of member 26 preferably is spaced vertically from the upper end of guide member 20, as shown in FIG. 1 of the drawing. 
     Tool 10 may be used to finish the muzzle end surfaces of either single barrel or double-barrel firearms. FIG. 3 of the drawing shows use of tool 10 in association with the barrel 34 of a shotgun of the former type. Guide member 20 has been inserted into the illustrated muzzle end of barrel 34 and tool 10 has been moved downwardly to bring the file teeth 28 upon the bottom surface of member 26 into overlying engagement with the end surface of the barrel&#39;s muzzle. The concentric relationship between guide member 20 and barrel 34 insures that the bottom surface of member 26 is perpendicular to the projected longitudinal axis of the barrel. Upon rotation of shank 12 of tool 10, via the previously described drive means shown in FIG. 1 and secured to its upper end portion, the file teeth 28 upon the bottom surface of member 26 therefore precisely &#34;square off&#34; and smoothly finish the muzzle end of barrel 34. If further reduction in the length of barrel 34 should be required, the use of tool 10 is continued until the barrel has been shortened to the desired extent. The previously mentioned vertical spacing between member 26 and guide member 20 permits escape in a radially-inwardly direction, as well as in a radially-outwardly direction, of the metal filings and the like produced during use of tool 10. The smoothness of the nylon or similar material of which guide member 20 is formed prevents the latter from marring the interior surfaces of barrel 34, during use of tool 10, notwithstanding the close fitting relationship between member 20 and the barrel. 
     FIG. 4 of the drawings shows use of tool 10 in association with the two barrels 36, 38 of a double-barreled shotgun. The diameter of member 26 is sufficiently great that when guide 20 is inserted into either barrel 36 or 38 of such gun, member 26 overlies the end surfaces of both barrels and of a rib-like member 40 customarily secured thereto. Use of tool 10 therefore simultaneously finishes the end surfaces of both barrels and of rib 40. 
     While a preferred embodiment of the invention has been specifically shown and described, this was for purposes of illustration only, and not for purposes of limitation, the scope of the invention being in accordance with the hereinafter presented claims.