Patent Publication Number: US-6705195-B1

Title: Method and apparatus for gun barrel cooling

Description:
TECHNICAL FIELD 
     The present invention relates to the field of firearms and more particularly, to highly precise examples of such apparatus as used in competitive target shooting, wherein every variable factor influencing accuracy must be consistently maintained on successive shots. 
     BACKGROUND 
     Competitive target shooting is pursued at many levels, from that of an Olympic event to a recreational pastime. Serious competitors take great pains in their selection and fine tuning of equipment. Ballistic experimentation with different combinations of bullet weights, powder types and charges, together with painstaking preparation and hand loading of cartridges is a given. While the human aspects of maintaining an accurate point-of-aim, including compensation for cross-winds, are basic differentiating factors in scoring, other factors affect the accuracy with which a round strikes at the point-of-aim. It is the reduction of variation in these other factors that is essential to approaching the unattainable, “perfect marksmanship”. In the case of a rifle, bedding of the barrel and receiver in the stock may be critical to accuracy. Dynamic characteristics of the barrel, that is, tube vibrations induced by discharge, may also be critical. In short, any physical effect that can vary, ever so slightly, from one round to the next, will affect the point-of-aim accuracy achieved by a given rifle. Skilled marksmen know it is desirable to maintain a uniform barrel temperature for every group of shots, because barrel temperature variations, especially uneven barrel heating or cooling, will degrade accuracy. Thus, at the highest levels of competition, skilled marksmen prefer to sight their rifle in hot, fire several warm-up groups before shooting for score, and hope for cooling periods between firing sequences to hold fairly uniform barrel temperatures. Barrel temperature control may be quite difficult under match conditions, especially while trying to avoid uneven cooling. 
     Military requirements are more severe. Here accuracy is not the issue so much as barrel life. Rapid fire sequences, without adequate cooling periods, will overheat the barrel so much that the rifling grooves are washed out and the barrel is ruined. In military service, it is a common practice to carry a spare barrel as a back-up, or as an exchange to allow cooling periods. 
     Therefore, a first object of the present inventions is to provide method and apparatus for enhancing the rate of barrel cooling. A second object of the present inventions is to provide method and apparatus for uniform barrel cooling at this enhanced rate. A third object is to provide method and apparatus that can be implemented under actual field conditions. Another object of the present inventions is to provide readily usable apparatus for extending barrel life under field conditions. Yet another object is to achieve these results at a reasonable cost to the end user, while still allowing a profit incentive for commercial production and distribution. 
     SUMMARY OF THE INVENTION 
     The present inventions contemplate improved methods and apparatus for gun barrel cooling. These inventions relate to or employ some steps and apparatus well known in the arts and therefore, not the subject of detailed discussion herein. The present inventions comprise improved methods and apparatus for cooling the barrel of a gun providing that the gun has a receiver configured to receive a magazine. 
     In a preferred embodiment of the present inventions the shell of a magazine for a given firearm, normally holding a plurality of rounds, is gutted to provide an appropriate housing. As an alternative, a similar part can be formed in sheet metal or plastic. A small, DC fan, of the type commonly used for circulation of cooling air through the interior of electronic devices and of a size suitable for mounting within the transverse inside dimensions of the housing, provides air flow for cooling. The mounting location of the fan is such that its air outlet will be directed into the chamber of the firearm when the housing is installed in the manner of a magazine. A DC power supply, preferably included inside of the housing, in the form of one or more batteries and a circuit connector/disconnector, completes this embodiment of the present inventions. The circuit connector/disconnector may be located where it is automatically operated by insertion of the barrel cooler housing into the receiver, or it may be located where it is accessible for manual operation. A useful accessory, for firearms having a bolt that does not lock in a retracted position on an empty chamber, is a bolt stop plate at the rear of the housing. Another useful accessory is an indicator flag, which extends from the ejector port when the barrel cooler is inserted, making it obvious that the weapon is in a safe condition. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are incorporated into the specification to assist in explaining the present inventions. The drawings illustrate preferred and alternative examples of how the inventions can be made and used and are not to be construed as limiting the inventions to only those examples illustrated and described. The various advantages and features of the present inventions will be apparent from a consideration of the drawings in which: 
     FIG. 1 is a perspective view of a preferred embodiment of the barrel cooling apparatus of the present inventions; 
     FIG. 1A is a view, similar to the view of FIG. 1, of a prior art, multiple round magazine; 
     FIG. 2 is a cross-section view of the barrel cooling apparatus of FIG. 1, as seen along cutting plane  2 — 2 ; 
     FIG. 3 shows a detail view of a circuit connector/disconnector and battery arrangement; 
     FIG. 4 shows an alternative, manually operated circuit connector/disconnector for a second preferred embodiment of the present inventions; and 
     FIG. 5 shows a remote power supply and circuit connector/disconnector as used for another preferred embodiment of the present inventions. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The present inventions are described in the following by referring to drawings of examples of how the inventions can be made and used. In these drawings, reference characters are used throughout the views to indicate like or corresponding parts. The embodiments shown and described herein are exemplary. Some details are well known to those skilled in the art, and as such are neither shown nor described. 
     FIG. 1 is a perspective view of a preferred embodiment of gun barrel cooler  10  of the present inventions, showing housing  12 , with the working parts internally mounted in a manner best understood when considered in conjunction with following FIGS. 2 and 3. In order to appreciate the present inventions, it is necessary to understand the dimensional similarities of housing  12  to magazine housing  62  of the multiple round magazine  60  shown in prior art FIG.  1 A. Magazine  60  is adapted by size and shape to fit a specific model firearm, as are embodiments of the present inventions. Magazine  60  is a companion part which is inserted into the receiver of a given firearm to feed successive rounds for firing. After a round is fired, the empty casing is extracted by rearward retraction of a sliding member and spring  64  positions the next round  66  for insertion into the firing chamber. Forward movement of the sliding member then chambers round  66  for firing. For firearms having a sliding member that does not lock in a retracted position on an empty chamber, bolt stop plate  22  may be mounted to housing  12  behind fan assembly  14 , to hold the sliding member in a rearward position. Indicator flag  24  may also be provided, so that insertion of barrel cooler  10  will be obvious to range safety observers. Indicator flag  24  is flexible, and curved slightly to extend out of the ejector port of the receiver when the barrel cooler is inserted and should be colored orange, to make it as obvious as is possible. 
     FIG. 2 is a cross-section view taken through fan assembly  14 , along cutting plane  2 — 2 , at the center line of fan impeller  19  and fan motor  18 . Cooling fan assembly  14  includes fan motor  18  and shroud  16 . Shroud  16  has air inlet  40 , hidden in FIG. 1, but clearly shown here, and air outlet  50 . It is to be noted that air outlet  50  is located in much the same relative position to housing  12  as is next round  66  to magazine housing  62 . When barrel cooler  10  is inserted into a firearm in the place and manner of magazine  60 , with the sliding member in the retracted position, air outlet  50  is in alignment with the firing chamber. The rotation of impeller  19  is directed to draw air in through air inlet  40 , for discharge from air outlet  50 . Thus, a flow of cooling air is drawn from the open receiver and passed directly into and through the gun barrel. Fan assembly  14  is a close fit inside of housing  12 , so that adhesive bonding is a preferred means of attachment therein. Here also is shown the manner of mounting impeller  19  for rotation with the output of fan motor  18 . 
     FIG. 3 provides a clearer view of bracket  20 , which provides a suitable structure for the mounting of normally open circuit connector/disconnector  26  and battery  30  within housing  12 . Bracket  20  is made to fit closely to the internal dimensions of housing  12 , where it may be affixed by welding, riveting or bonding. Circuit connector/disconnector  26  is mounted to bracket  20  by panel mounting nut  21 , so that actuator  28  extends through housing  12 , where it is actuated when barrel cooler  10  is inserted into the firearm receiver. Battery  30  snaps into terminal clip  23  so as to be readily replaceable, and terminal clip  23  is attached to bracket  20  by adhesive bonding. Clearly, the mounting arrangement of the battery  30  and terminal clip  23  is a matter of the designer&#39;s choice. As shown in FIG. 1, insulated wire  33  provides connection for the negative terminal of battery  30  to fan motor terminal  38 . The positive terminal connection of battery  30  is by insulated wire  32 , by way of normally open circuit connector/disconnector  26  and insulated wire  34  to second fan motor terminal  36 . Thus, when circuit connector/disconnector actuator  28  is depressed, normally open circuit connector/disconnector  26  is closed and fan motor  18  is activated. 
     FIG. 4 shows a second preferred embodiment of the present inventions as barrel cooler  100  wherein housing  112  is equivalent to housing  12  of barrel cooler  10 . Fan assembly  114  is connected by insulated wires  132 ,  133  and  134  to battery  130  by way of terminal clip  123 . Barrel cooler  100  differs from barrel cooler  10  only in that circuit connector/disconnector  126  is manually operated by selectively positioning actuator  128  to electrically connect or disconnect wires  132  and  134  and provide air flow from outlet  150 . 
     FIG. 5 shows another preferred embodiment of the present inventions as barrel cooler  200  wherein housing  212  is equivalent to housing  12  of barrel cooler  10 . Fan assembly  214  is connected by insulated wires  233  and  234  to battery pack  230  by way of circuit connector/disconnector  226 , which is inserted into socket  225  where contacts  222  and  224  are connected, as are contacts  228  and  232 . In this manner, fan motor terminals  236  and  238  are connected by two conductor cable  239  to the positive and negative terminals of battery pack  230 . 
     The embodiments shown and described above are exemplary. It is not claimed that all of the details, parts, elements, or steps described and shown were invented herein. Even though many characteristics and advantages of the present inventions have been described in the drawings and accompanying text, the description is illustrative only. Changes may be made in the detail, especially in matters of shape, size, and arrangement of the parts within the scope and principles of the inventions. The restrictive description and drawings of the specific examples above do not point out what an infringement of this patent would be, but are to provide at least one explanation of how to use and make the inventions. The limits of the inventions and the bounds of the patent protection are measured by and defined in the following claims.