Abstract:
This invention is directed to a rifle barrel and a method for modifying a pre-existing rifle barrel comprising dissembling said pre-existing rifle so that said barrel is removed from said pre-existing rifle placing said barrel in a sleeve having an inner diameter larger then said diameter of said barrel for receiving said barrel thereby defining a void arranged between said barrel and said sleeve when said barrel is placed in said sleeve reducing the outer diameter of said barrel near the breach end of said barrel so that said sleeve will cover said barrel up to the action of said rifle when said barrel is placed in said sleeve filling said void defined by said barrel and said sleeve with filler material attaching a weld-on thread assemble to said sleeve at the muzzle end of said barrel and assembling said pre-existing rifle with said barrel placed in said sleeve.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims priority on U.S. provisional patent applications: Ser. No: 61/176,200; Ser. No. 61/230,450 and Ser. No. 61/287,785. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention is directed to a weapons system having a rifle, shotgun or cannon barrel. This invention is directed to the construction of a rifle, shotgun or cannon barrel and method of modification providing a sandwich barrel design for reducing heat and harmonics and for improving accuracy. 
       BACKGROUND 
       [0003]    It has been long understood that a rifle&#39;s barrel changes shape and moves in multiple directions every time the rifle is fired. This effect is also found in shotgun and cannon barrels. In some instances, this movement of the barrel has been coined “barrel whip” and is when a weighted object (bullet) travels down the tubular barrel under intense gas pressure generally defined as when the barrel away from its “static” state. Barrel whip can occur when the bullet accelerates into a rapid spin, when the stock drops significantly so the muzzle rises when the rifle is fired, or when a pressure wave travels the length of the barrel. In the case of shotguns and unrifled cannon barrels, the “barrel whip” largely results from the pressure wave traveling along the barrel. 
         [0004]    Barrel whip reduces the accuracy of the projectile expelled from the barrel and, therefore, the ability of a shooter to hit a target. Historically, manufacturers of barrels have simply accepted that the barrel&#39;s movement can&#39;t be eliminated. The remedy was to manufacture the barrel so that at least the movement was consistent with each shot. With a combination of cartridge loads and a consistently moving barrel whip, a rifle can be made more accurate by matching the load with the barrel. However, this requires that cartridge loads be customized to match each individual barrel and requires a high degree of customization. 
         [0005]    Further, with each shot, the chamber can swell and produce an annular wave that travels between the muzzle and the breech. As the annular wave travels down the barrel, the bore diameter changes slightly as a result of the wave. If the bullet exits the barrel coincidentally with the wave at the muzzle, the bullet accuracy is greatly reduced since the bore and the bullet will be ejected through a bore that is made larger due to the wave. Traditional attempts to avoid this problem have been to change the cartridge load so that the bullet does not exit the barrel when the annular wave is at the muzzle. Again, this involves a high degree of customization and requires that cartridge loads match each individual barrel. 
         [0006]    Further, as rounds arc shot through a barrel, the barrel heats and the metal expands, becomes more flexible, and, therefore, the effect of barrel whip and any annular waves increases. Some tests have found that the center of the bore can change as much as 0.001 inches between the barrel temperatures of 77° F. (ambient) and 122° F. While the number of rounds that it takes to heat a barrel from ambient to over 120° F. varies greatly with the type for round, the type of barrel and other factors, such temperature changes can occur in as little as four or five rounds. Therefore, for multiple shots, the heat generated by the shots can adversely affect the accuracy of the barrel. This effect is exemplified in  FIG. 4 . 
         [0007]    It would be advantageous to have a weapons system that was manufactured or modified to reduce the effects of barrel whip, annular or pressure waves, and heat produced when firing. Additionally, it would be advantageous to a weapons system that was manufactured or modified so that it would not be necessary to match cartridge loads with barrel characteristics so that barrel accuracy was not necessarily cartridge specific. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is accomplished by providing a sleeve for enclosing a weapons system barrel; a void defined between the weapons system barrel and the sleeve; and filler material filling the void. This invention also includes an outer sleeve positioned around a plurality of barrels in a circular configuration thereby encircling the barrels; an inner sleeve positioned in the space defined by the barrels and internal to the circular configuration thereby defining a void between the outer and inner sleeve; and filler material placed within the void. 
         [0009]    This invention also includes the method of removing external fitting from an existing weapons system barrel; placing a sleeve around the barrel thereby defining a void between the sleeve and the weapons system barrel; and placing filler material within the void. This invention also includes the method of providing a weapons system barrel; placing a sleeve around the barrel thereby defining a void between the sleeve and the weapons system barrel; and placing filler material within the void. This invention also includes providing a plurality of barrels arranged in a circular configuration; placing an outer sleeve around the barrels encircling the barrels; placing an inner sleeve in the space defined by the barrels and internal to the circular configuration thereby defining a void between the outer and inner sleeve; and placing filler material within the void. 
     
    
     
       DESCRIPTION OF THE DRAWINGS  
         [0010]    This invention is more readily understood by referring the following drawings: 
           [0011]      FIG. 1A through 1C  are schematics of a traditional barrel; 
           [0012]      FIG. 2A through 2E  are schematics illustrating the need for the invention; 
           [0013]      FIG. 3A through 3B  are schematics illustrating the need and results of the invention; 
           [0014]      FIG. 4  is a chart illustrating heat building in a barrel; 
           [0015]      FIG. 5A through 5D  are schematics of the invention; 
           [0016]      FIG. 6A through 6F  are schematics of the invention; 
           [0017]      FIG. 7  is a flowchart illustrating the invention; and, 
           [0018]      FIG. 8A through 8B  are schematics of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Referring to  FIG. 1A through 1D , a barrel  10 , which may be part of a shotgun, rifle, or cannon weapons system, is used as an example in describing this invention to one skilled in the art. It should be understood that this invention can be used with and applied to weapons systems using a barrel for expelling a projective, and in particular for a shotgun, rifle, or cannon barrel. For example, the Ruger 10/22 firing .22 caliber rounds to 12 gauge shotguns and to large caliber cannons such as the 120 mm smooth bore cannon of the United State M1A1 Abrams. 
         [0020]    Generally, such weapons systems include a barrel  10  having a receiver  12  and muzzle  14 . Open sights  16   a  and  16   b  can be included optionally carried by barrel  10 . Round  18   a,  which may be a shotgun shell containing multiple shot or a single slug projectile cartridge round, is received by barrel  10 . Rounds can be either inserted individually into the breech or through a magazine configuration  20  for holding multiple rounds as is well known to those skilled in the art. In the magazine configuration, the rounds are biased in a direction such as shown by  22  so that when the action of the rifle or shotgun is cycled, rounds are inserted into the breech and can be filed. The barrel defines a bore  24 . The bore can be a smooth bore, such as in a shotgun or cannon, or contain rifling as is common in most rifles and smaller single projectile fire arms such as handguns. 
         [0021]    Referring specifically to  FIG. 1B , in one embodiment, the outer diameter of a portion of the barrel near the breach end of the barrel can be reduced through metalworking such as machining, routing, etc. The outer diameter of the barrel can be reduced to allow the sleeve to fit over this portion of the barrel. In one embodiment, it may be necessary to press the sleeve onto the barrel due to the fit between the barrel and the sleeve. In one embodiment, the outer diameter portion of the barrel shown as  15  has its diameter reduced to that less than the portion of the barrel shown as  13  so that the sleeve has a tighter fit at portion  13  than the rest of the barrel. In one embodiment, a shoulder stop can be cut into the barrel to allow the sleeve to be placed over the barrel where one end of the sleeve is proximate to the shoulder stop so that the portion of the barrel behind the shoulder stop and the outer diameter of the sleeve are generally flush. 
         [0022]    Referring to  FIG. 2A  through  FIG. 2E , a cartridge (or shotgun shell/round)  26  is shown having case  28  and bullet  30 . In the case of a shotgun, bullet  30  may be a single projectile (slug) or a plurality of small projectiles commonly referred to as shot. The construction of shotgun shells is well known to those skilled in the art and thus not specifically illustrated. It should be understood by those of ordinary skill in the art that the present invention is applicable to any and all weapons systems utilizing a barrel to eject a projectile(s) regardless of the form of the round or number of projectiles contained in a single cartridge. Case  28  can contain gunpowder or other explosive  6  that when ignited, expands and pushes the bullet through the bore. In the case where the bore contains rifling, the bullet is caused to rotate in a direction illustrated as  32  which causes the bullet to spin within and upon leaving the bore. When the bullet is pushed out the bore, torque is applied to the barrel and the barrel can experience barrel whip shown as  34 . As previously explained, barrel whip adversely impacts the accuracy of the barrel as the bullet can leave the muzzle when the bore is “off target.” It should be noted that the barrel whip can be in a linear direction or circular so that the barrel can whip in two or three dimensions. 
         [0023]    Additionally, the expanding gas from the ignited explosive in the case can create an annular wave  36  that initially travels in a direction  38  down the barrel and will rebound in a direction opposite  38  and “bounce” back and forth for some period of time along the barrel. When the annular wave reaches the muzzle, the muzzle of the barrel can “whip” so that the bore moves “off target”. This effect is particularly undesirable when bullet  30  and annular wave  38  reach the muzzle approximately contemporaneously. The barrel whip effect is equally undesirable in smooth bore barrel weapons such as shotguns and cannons. 
         [0024]    Given the multiple undesirable forces on the barrel, the accuracy of any rifle, shotgun or cannon is significantly compromised, particularly after multiple rounds are fired in relatively quick succession. Referring to  FIG. 3A and 3B , the results of a rifle barrel that has not been modified or manufactured with the present invention is illustrated as  40 . The following test results accompany the illustration shown as  40 : 1942 Lee Enfield .303 cal bolt action resulted in a grouping of five shots spanning 22 inches; 1944 Tula, Mosin Nagant 7.62×54 cal Russian bolt action resulted in a grouping of five shots spanning 18 inches; and 1991 Remington Model 700 .7 mm cal magnum bolt action resulted in a grouping of five shots spanning 6.5 inches. In the case of a shotgun, the shot pattern also wanders unpredictably as a result of the barrel whip effect. 
         [0025]    Once the invention was applied to the above rifle barrels, the results are illustrated as  42 . The following test results accompany the illustration shown as  40 : 1942 Lee Enfield .303 cal bolt action resulted in a grouping of five shots spanning 3.5 inches; 1944 Tula, Mosin Nagant 7.62×54 cal Russian bolt action resulted in a grouping of five shots spanning 2.5 inches; and 1991 Remington Model 700 .7 mm cal magnum bolt action resulted in a grouping of five shots spanning 1 inch. Therefore, this invention resulted in an accuracy improvement of approximately 84%, 86% and 85% respectively per each of the above rifles. Application of the barrel treatment to shotguns (single or double barrel) shows notable improvement in accuracy as well, either for shot or slug projectile cartridges. 
         [0026]    Referring to  FIG. 5A through 5D , the invention&#39;s application and construction will be described in more detail. A sleeve  44  is placed over barrel  10  of a shotgun, rifle or cannon. Sleeve  44  defines a muzzle sleeve opening  46  and a breech sleeve opening  48 . In one embodiment, the breech opening is proximate to the receiver or breech of the barrel so that the sleeve approximately seals around the barrel shown as  48   a.  In another embodiment, the breech sleeve opening is a predetermined distance  49  from the breech or receiver such as five to twelve inches as shown in  48   b.  The muzzle sleeve opening is fit to generally be flush with the muzzle of the barrel. The sleeve and the outer boundary of the barrel define a void  50 . In one embodiment the sleeve is manufactured from stainless steel. The sleeve can also be manufactured from other metals, composite plastics, or a fibrous material sufficient to maintain its structure while being exposed to the heat and vibrations of a weapons system barrel. The sleeve can be generally circular or polygonic in shape. 
         [0027]    In one embodiment, the sleeve is generally twice the diameter of the rifle, shotgun or cannon barrel. In one embodiment, the barrel is machined to reduce the diameter of the barrel prior to installing the sleeve. This allows for the use of a smaller diameter sleeve and can assist with replacement of the modified barrel back in the stock of the rifle or other component of the weapons system. It should be noted that the sleeve need not be circular in shape and can be any shape including hexagon, oval, square and such. 
         [0028]    In some configurations, it may be necessary to apply a sealant such as epoxy or putty at the sleeve breech opening so as to generate a seal between the sleeve and the barrel. Once the sleeve is in place, the barrel and sleeve are placed in a vertical position, in one embodiment as shown in  FIG. 6A through 6F . A barrel centering member  52  is used to center the barrel in the sleeve. In one embodiment, the barrel centering member  52  contains a distal member  54  that is received in bore  24 . Spacing members  56   a  through  56   c  carried by spacing member  52  positions the barrel generally parallel to the center axis of the sleeve wherein the center axis of the sleeve coincides with the center axis of the barrel. It should be noted that placement of the barrel in the sleeve need not be exact to achieve the benefits of this invention. 
         [0029]    In one embodiment, a realignment tool  84  is used to align the barrel in the sleeve. In this embodiment, the muzzle end  86  is placed in the bore of the barrel. The end cap or weld-on threads are placed on the muzzle end generally at  88  so that when the alignment tool in placed in the bore, the end cap or weld-on threads can be aligned with the sleeve. A muzzle brake can be placed generally at  90  over the alignment tool and attached to the end cap so that weld-on threads, muzzle brake and alignment tool, carried within the muzzle brake and weld-on tool, so that when the alignment tool is inserted into the bore, the barrel can be aligned within the sleeve and the sleeve can be aligned with the weld-on tool and muzzle brake. 
         [0030]    Once the sleeve is in place and the barrel is positioned with the sleeve, filler material  58  is placed in void  50  defined by the sleeve and the barrel. In the case of double barrel shotguns, the sleeve is constructed and arranged to enclose both barrels and the filler material  58  is then simultaneously placed in the void surrounding both barrels in the same manner as described above for a single barrel. In one embodiment, the filler material is a hydraulic type cement that when mixed with water will harden rapidly to produce a permanent bond. The filler material can be applied in a semi-fluid state and poured between the sleeve and the barrel. 
         [0031]    In one embodiment the filler material is hydraulic cement comprising at least 50% calcium sulfate and 48% or less portland cement and may contain amorphous silica, alumina, limestone dust, clay, quartz, calcium hydroxide and calcium sulfo aluminate. In one embodiment the filler material is hydraulic cement comprising at least 90% calcium sulfate and 10% or less portland cement. The filler material can also be epoxy or resins that are able to withstand the heat generated from the firing of a barrel of a weapons system. In one embodiment, the filler material is mixed with metal shavings to enhance the filler materials ability to absorb and quickly dissipate heat from the barrel. 
         [0032]    In one embodiment, a muzzle brake  60  can be installed after the sleeve and filler material have been installed. In one embodiment, a weld-on end cap  61  can be attached to the muzzle end of the sleeve. This weld-on end cap can be simply and end cap defining a center opening that is the same diameter of the bore of the barrel. The opening of the end cap can also be slightly larger than the barrel diameter. In one embodiment, the weld-on end cap has a threaded portion  65  that can receive a corresponding threaded portion (not shown) of a muzzle brake, or other attachment to attach the muzzle brake of other attachment to the threaded end cap allows for its attachment and removal without having to attach or remove the end cap. 
         [0033]    In another embodiment, this invention can be used in a Gatling gun configuration. The Gatling gun configuration fires during a rotating cycle that reaches speeds of up to 3000 revolutions per minute. This centrifugal force causes the barrels to flex away from the axis of the circumference defined by the plurality of barrels. This force causes an undesirable U-shape to form along the length of the barrels creating a form of barrel whip, perpendicular to their axis during firing, reducing accuracy. Further, the rate of fire for the Gatlin gun configuration generates a tremendous level of heat further exacerbating the U-shape formation. One application of the Gatling gun confirmation is the Avenger used by the A10 aircraft. In practice, the cannon of the A10 is limited to one- and two-second bursts to avoid overheating and to prevent barrel wear due to the U-shape flexing. 
         [0034]    In application for the Gatling gun configuration, an outer sleeve  84  surrounds a plurality of barrels  10   a  through  10   g.  An inner sleeve  86  is placed interior of a circumference defined by barrels  10   a  through  10   g  thereby defining a void  88  between the outer sleeve and the inner sleeve. Filler material can be placed in void  88  as described herein. 
         [0035]    Referring to  FIG. 7 , the method of practicing this invention will be explained in more detail. External filling are removed from the barrel at  62 . The barrel can be de-greased and painted at  64 . The portion of the stock that received the barrel can be routed to increase its size so that is can accommodate the increased diameter of the rifle barrel placed in the sleeve at  66 . If the barrel diameter needs to be reduced at  68 , the barrel is reduced at  70 . In one embodiment, the barrel exterior surface is roughed to promote a more cohesive bond between the filer material and the barrel. Such roughing can be accomplished through the use of abrasive mean such as sandpaper. In one embodiment, the barrel diameter is only reduced toward the action end to allow a tighter fit of the sleeve at the action end than the muzzle end. In one embodiment, circumferential grooves, such as  92   a  ( FIG. 8B ) are cut into the barrel to provide larger void between the sleeve and the barrel for receiving filler material. The barrel can be re-crowned at  71 . The barrel can also be painted at  71 . 
         [0036]    The sleeve is measured and cut to the appropriate length based upon the barrel being modified. In one embodiment, the action end of the sleeve is beveled and squared so that it fits square against the action end of the barrel. A sleeve is placed over the barrel at  72 . In one embodiment, the sleeve is pressed against the barrel using a press. If there is a gap between the sleeve breech opening and the barrel as determined at  74 , the gap should be closed at  76 . The action of the weapons system is locked and the muzzle centering device is installed at  78 . The bore of the barrel is plugged and filler material is placed in the void defined by the barrel and the sleeve at  80  and the filler material is allowed to cure. In one embodiment, the twelve inches or so at the muzzle end of the sleeve is heated prior the filler material curing. The external fittings are replaced at  82  which can include tightening the muzzle brake to insure proper clocking (alignment), welding on the end cap, weld-on threads or muzzle brake. In one embodiment, clamps are used to secure the end cap, weld-on threads, or muzzle brake to the sleeve to assist with proper attachment when welding. The sleeve and some of the exposed portion of the barrel can be finished through painting, polishing, etc. The end cap, weld-on threads or muzzle brake, if used, have the center opening drilled to insure that there is no grazing when a bullet leaves the muzzle of the rifle barrel. The sleeve can be marked for maximum caliber and the muzzle brake can be marked for the specific chambering of the rifle. 
         [0037]    While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.