Ballistic optimizing system for rifles

Abstract: A ballistic optimizing sytem for use on a preferably bedded rifle comprising a movable weight element secured to the end of a rifle barrel such that said weight element can be moved axially along said barrel to change the effective weight applied for dampening purposes and having an indicator for indicating the relative position of said weight element on said barrel and further including an additional weight releasably secured to said movable weight element and ports through said weight element to allow gas escape.

Description: This invention relates to a method for optimizing the firing accuracy of a rifle being charged with a particular ammunition type. There has long been a desire among marksmen for firearms to be as accurate and consistent as possible during firing. This desire is particularly characteristic of marksmen who engage in rifle target shooting competitions. Consequently, considerable effort has made to eliminate or at least minimize those factors that adversely affect accurate shooting. It is well recognized that two of the factors adversely affecting accurate rifle marksmanship are (1) the barrel vibration which inevitably occurs upon firing of the weapon and (2) the recoil to which the marksman is subjected upon firing. Attempts to eliminate such barrel vibration and recoil have involved the use of various types and kinds of bedding materials as shock absorbers and dampeners between the barrel and the action assemblies and stocks of a rifle. the kinds and positioning of mounting screws associated with the components of a rifle have been the subject of design scrutiny. Different stock and barrel configurations have been tried. Nevertheless, inconsistent paths of trajectory of ballistic slugs discharged from their muzzles remain inherently characteristic of rifles. These inconsistencies are particularly objectionable with the firing of certain factory loaded cartridges, due to the vibrations of the barrels which are inevitably set in motion upon discharge of a firearm which is not designed specifically for use with that cartridge. It has been recognized that, in some cases, it is possible to "match" a particular rifle with a particular cartridge to minimize barrel vibration, thereby to increase accuracy. To "match" a cartridge with a particular rifle, it may be necessary to vary slug weight, the type and amount of powder used, or other factors, such as the center of gravity of the rifle. A best match of ammunition will result in the exiting of a slug from the barrel muzzle at or as near as possible to the peak of the vibration curve for the barrel vibrations induced by the firing of the rifle. When the exit of the bullet is at a peak of the vibration curve, minimal bullet path deflection occurs. Weights have been heretofore attached to the muzzle ends of rifle barrels as a means of dampening barrel vibrations set in motion by discharge of the firearm. U.S. Patent No. 4,726,280, for example, discloses mounting a muzzle member, which serves as a counterweight on the muzzle end of a gun barrel. The muzzle member is threaded onto the barrel, and is locked in place. Anschutz and co. G.M.B., through the 1989 catalog of its distributor, Precision sales International, Inc of Westfield, Mass., discloses, at pages 11 and 16, barrel extensions for rifles that include removable weights. Interchanging these weight enables a marksman to vary selectively the amount of weight used for dampening purposes. Muzzle brakes have also been used in the past with rifles. The known muzzle brakes function to exhaust propulsion gases as a means of reducing recoil and of dissipating propulsion gases in a direction or directions other than out the muzzle of the barrel. The muzzle brakes heretofore known characteristically cause a noticeable increase in noise and concussion to the marksman. The known muzzle brakes have been attached to the muzzle end of a rifle barrel, and thus inherently add a dampening weight. Such muzzle brake is amongst others disclosed in US-A-2.712.193. This patent concerns a choke mechanism for reducing the recoil and the noise and comprises therefore a sleeve with openings. This sleeve carries on one end a compression nipple and is fixed by means of a collar and a locking ring on the barrel which is provided with slits and slots. This mechanism has no dampening effect and has no influence on the precision of the firing. US patent No 4.635.528 discloses a device for controlling the muzzle climb, comprising a body provided with screen ports and gas vent slots and a cap adjustably screwed on the body for covering more or less the gas vents slots and the screen ports to reduce or increase the volume of the chamber inside the body and to control the quantity of gas escaping through the ports and the slots from the chamber. The ballistic optimizing system (BOS) of the present invention is for the purpose of increasing the shooting accuracy achievable with rifles. The invention provides an adjustable structural means to dampen barrel vibrations. Preferred embodiments additionally provide structural means to reduce recoil without generation of any significant sound increase, and in some instances with a slight sound reduction. The system of the invention adds a weight element to the muzzle end of a rifle barrel. The effective center of gravity of the barrel is adjustable changed by positioning the weight element axially along the barrel, either toward or away from its muzzle end. By this means, it becomes possible to "match" the rifle to a particular ammunition. That is, the slug of a bullet for which the weight element is properly positioned will exit the muzzle at the optimum time to experience minimum travel deflection. Thus, it is unnecessary to select a cartridge based upon the inherent responses of a particular rifle. Accordingly, factory loaded ammunition can be shot with accuracies heretofore unobtainable. Moreover, different factory loaded cartridges can be fired accurately from the same riffle by merely making appropriate system adjustments. According to the present invention, the weight element is repositioned selectively forwardly toward or rearwardly away from the muzzle end of a rifle barrel. The mass of the weight element thus becomes a critical mass. An appropriate mechanism, such as a lock nut, is used to retain the weight element in selected position and contributes some mass to the weight element. For purpose of this disclosure, the locking mechanism is regarded as a portion of the weight element, and its mass is a part of the critical or adjustable mass. The rifle is matched to a particular ammunition by positioning of the weight element to an empirically determined location, referred to as the "sweet spot". The "sweet spot" is that location of the weight element along the axis of a rifle barrel at which the trajectories of a series of substantially similar ballictic slugs discharged from the muzzle of the rifle held in a stationary position exhibit a minimum deviation. The weight element may need to be repositioned to find the "sweet spot" of the rifle for a different cartridge. It has been found that in some instances even very small movements of the critical mass will effect a significant change in the accuracy of a rifle fitted with the present ballistic optimizing system. In one presently preferred embodiment of the invention a lock nut is threaded onto a rifle barrel and an interiorly threaded, tubular weight is also threaded onto the barrel to engage and lock against the lock nut. The lock nut has a skirt that telescopes over a portion of the rifle barrel. A graduated linear scale on the barrel cooperates with an edge of the skirt to provide an indication of the position of the lock nut relative to the muzzle of the riffle barrel. A scale around the edge of the skirt is indicative of the extent to which the lock nut and skirt are rotated between full rotations, which full rotations are indexed on the linear scale. In another presently preferred embodiment of the system of the invention, the wall of an interiorly threaded, tubular weight is provided with angled ports and straight ports therethrough to allow escape of propellant gases. The weight then additionally functions as a muzzle brake to reduce recoil of the rifle when it is fired. A tubular end plug/weight may be threaded into the end of the tubular weight remote from the muzzle end the rifle to allow passage of a fired ballistic slug while also providing a deflector for concurrently discharging propellant gases. The plug/weight additionally provides a means for making major changes in the "effective weight" (an alternative designation of the position of the center of gravity of the rifle) applied to the muzzle end of the barrel. Plug/weights of varying size, weight and dimensions can be selected for use. The shape and pattern of the ports and the shape of the deflecting surface of the plug/weight provide for gas escape to minimize recoil without significant change in noise resulting from firing. Preferred constructions arrange the ports so that the propulsion gasses escaping through adjacent ports mutually impinge. In the drawings, which illustrate what is currently regarded as the best mode for carrying out the invention: figure 1 is a top plan view of a first preferred rifle barrel vibration dampener of the system of the invention, mounted on a rifle barrel that is shown fragmentarily; figure 2 is a view in transverse section taken through the dampener of fig 1, but with the rifle barrel shown in elevation, for clarity; figure 3 is a pictorial view of a series of six test targets as actually fired upon with a fixed rifle equipped without the vibration dampener of the invention and with the dampener on the rifle and adjusted to provide different location settings of the weight; figure 4 is a view like that of fig 3, but showing seven test targets fired upon with a different rifle and using different ammunition than that of fig 3; figure 5 is a view like that of fig 2, but showing another preferred embodiment of the invention including a variable weight and a replaceable weight/plug that additionally functions as a muzzle brake; figure 6 is a fragmentary perspective view of a presently muzzle brake element; figure 7 is a fragmentary perspective view of a portion of a rifle barrel mounted to float on a layer of bedding material. In the illustrated preferred embodiment of figures 1 and 2, the system of the invention includes a rifle barrel vibration dampener, shown generally at 10, threaded onto a rifle barrel 11. The barrel 11 is stepped down at a shoulder 12 to a threaded section 13 that terminates in a muzzle 14 having a distal end 15. A lock nut 16 is threaded onto the section 13 and a skirt 18 of the lock nut extends therefrom to telescope around the barrel 11. The skirt 18 has an edge 19 and the skirt extends over the shoulder 12 so that edge 19 cooperates with a graduated linear scale 20 that has indices on the exterior surface of barrel 11. A linear scale 22 has indices in increments equally spaced around and marked on the skirt 18, adjacent to the bottom edge 19. The relationship between the indices on the linear scale 20, the threads between barrel section 13 and lock nut 16 and the indices of the linear scale 22 are preferably selected such that turning of the lock nut to turn the skirt one full turn will move the skirt axially, with respect to the barrel, a distance equal to that between adjacent index markings along the linear scale 20. A tubular weight 24 has one end interiorly threaded at 25, is telescoped over the distal end 15 and is threaded onto the threaded section 13 of the barrel to engage and to be tightly locked against lock nut 16. The weight 24 must be loosened before lock nut 16 can be turned to change the position of the lock nut relative to distal end 15 and must thereafter be tightened against the lock nut 16 to affix the position of the weight relative to the distal end. To ensure a secure locking engagement between the thread section 13 of the rifle barrel 11, lock nut 16 and threads 25 of tubular weight 24 that will not release upon firing of the gun, a nylon strip 26 is inserted into a groove provided across the threads 13. Thus, when the lock nut and tubular weight are threaded onto the barrel the threads 13, 25 cut into and deform the nylon strip 26, wedging it between the threads to prevent undesired release of the tubular weight and lock nut from the barrel. A typical target set of six targets 30-35, used for test firing of a particular rifle in this case a 22-250 Browning A-Bolt, using Federal 2.6 g (40 grain) ammunition, from a fixed location, is shown in figure 3. All firing was done at a range of 91.44 m (100 yards) and in three round groups. The 2.342 cm (0.922 inches) shot group of target 30 was fired from the test rifle before the vibration dampener 10 was installed on the rifle. The shot groups of test targets 31-35 were obtained using the same rifle with the vibration dampener 10 installed. The vibration dampener setting for each of the targets 31-35 were 3.0, 4.0, 5.0, 6.0 and 7.0 turns, respectively. The "sweet spot," for the rifle and ammunition tested was found to be at 6.0 turns, where a grouping of 0.543 cm (0.214 inches) was obtained. The same Browning 22-250 A-Bolt rifle was fired in the same manner at another target set of seven targets 40-46, figure 4, using Winchester 3.37 g (52 grain) ammunition. When the rifle was fired at the target 40, with the vibration dampener removed, a 1.55 inch shot group was obtained. The shot groups of the targets 41-46 were obtained using the rifle with the vibration dampener 10 installed. The vibration dampener settings for each of the targets 41-46 were 4.0, 5.0, 6.0, 7.0, 8.0 and 9.0 turns, respectively. The "sweet spot" for the rifle and ammunition tested was found to be at 8.0 turns where a grouping of 1.006 cm (0.396 inches) was obtained. In another test, a Browning A-Bolt, 30-06 caliber rifle was fired for accuracy at a range of 91.44 m (100 yards) and a three round group of 3.427 cm (1.349 inches) was obtained using Winchester 150 grain ammunition. The rifle was thereafter fitted with the vibration dampener of the invention and firing, using the same ammunition at a series of targets, until the "sweet spot" was found to be at 5.0 turns, where a group of 1.727 cm (0.680 inches) was observed. The same rifle, with the vibration dampener removed, was fired using Winchester 14.26 g (220 grain) ammunition to obtain a 4.862 cm (1.914 inches) group. The vibration dampener was refitted and at the 5.0 turns position a group of 1.221 inches was obtained. The "sweet spot" with this ammunition was found to be at the 6.0 turns position, where a group of 0.986 cm (0.388 inches) was obtained. Additional tests were conducted with 7mm Remington Magnum, .223 Winchester, 30-06 Springfield, .338 Winchester Magnum and .270 Winchester calibers. The test results were consistent with those reported previously in this disclosure. Another preferred embodiment for the vibration dampener of the system of the invention is shown generally at 50 in figure 5. The dampener 50 includes a rifle barrel 51, having a shoulder 52 and an exteriorly threaded portion 53 at the distal end 54 of the barrel. A lock nut 55 is threaded onto the threaded portion 53 and includes a projecting skirt 56. As in the previously disclosed embodiment, a linear, graduated scale 57 is provided on the outer surface and extends along the length of the rifle barrel 51. the skirt 56 has an edge 58 and another linear, graduated scale 59 is provided on the skirt at the edge 58. Also, as in the previously disclosed embodiment, a preferred relationship between the linear scales, the threads on section 53 and the lock nut are such that one full rotation of the lock nut 55 and scale 59 will move the lock nut along the length of the rifle barrel for a distance equal to that between index marks of the scale 57. The edge 58 of the skirt 56 serves as an indicator cooperating with the scale 57 to indicate the number of turns made to position the nut 55 relative to the distal end 54 of the barrel 51. A tubular weight element 60 has one end 61 interiorly threaded at 62 so that it can be threaded onto the threaded portion 53 of the barrel 51. The weight element 60 is eventually moved into locked engagement with a lock washer 63 that also engages the lock nut 55 to prevent undesired movement of the weight element 60 relative to the lock nut. The other end 64 of the weight element 60 is interiorly threaded to receive an exteriorly threaded boss 65 of a plug/weight 66. A lock washer 67 on the boss 65 engages the weight element 60 when the boss is fully inserted to prevent undesired movement of the plug/weight 66 relative to the weight element 60. Nylon strips 71 corresponding to the nylon strip 26 previously described in connection with the embodiment of figures 1 and 2 are also preferably inserted in grooves provided in the threads 62 and the threads 65a of boss 65. The strips 71 function more securely to lock the locking nut 55 and tubular weight element 60 to the rifle barrel and the plug/weight 66 to the tubular weight element 60. Spaced apart ports 68 extend at ninety degrees with respect to the central axis of the rifle bore. Three rows of eight equally spaced ports 68 are provided through the wall of tubular weight element 60. An additional row of eight ports 69, each of which is directed away from the central axis of the rifle bore at a thirty degree angle and extends rearwardly from the distal end 66a of the plug 66, is also provided through the wall of the element 60. The ports 68 and 69 allow propulsion gases to be discharged as a bullet is propelled through the barrel and out a bore 72 through the plug/weight 66. The weight element 60 thus additionally acts as a muzzle brake for the rifle on which it is used, and reduces recoil of the rifle when it is fired. The inserted end 65b of boss 65 helps divert through the ports 68 and 69 gases released upon firing of a bullet as the slug of the bullet travels through bore 72. The end 65b may be tapered, typically at a thirty degree angle with respect to the central axis of the bore 72 through the plug/weight 66. Plug/weight 66 increases the overall weight applied to the end of barrel 51 and the plug/weight 66 can be interchanged with other similarly constructed plug/weights to vary the overall weight applied to the end of the barrel 51. It is therefore possible to provide for major weight changes, such as may be necessary as the vibration dampener 50 is used with rifles manufactured by different manufacturers, different models of rifles, different caliber rifles, and different ammunitions. Tests were conducted to determine the effectiveness of the ballistic optimizing system shown in figure 5 with a variety of production rifles. for data recording purposes, the test rifles were identified as: Test Rifle Caliber A 30-06 Springfield B .270 Winchester C .300 Winchester Magnum D 7mm Remington Magnum E 22-250 Remington F .338 Winchester Magnum The rifles were test fired as received from production and were then re-bedded and test fired after installation of the ballistic optimizing sound suppressing system (BOS). The use of bedding has long been common and it is well recognized that proper bedding will increase the accuracy of a rifle. The rifle barrel is preferably mounted to float within a mounting well of the stock. The bedding is installed to fill the floating space between the barrel and well. As so positioned, it functions as a shock absorber. "Bedding" refers to a shock absorbent or stabilizer material, which is usually a synthetic rubber or similarly resilient elastomeric material. In the case of the test rifles, a two part pourable liquid urethane rubber bedding compound supplied by Devcon Corporation of Danvers, main under the tradename "FLEXANE 94" was used, as best illustrated by figure 7. The rubber bedding 80 between the barrel 82 and the stock 84 enhanced the accuracy of the BOS system in the rifles tested. The BOS was mounted to each test rifle after removal of two inches from the end of the respective barrels. The resulting configuration is shown in figure 5. The removal of the barrel end and addition of the BOS resulted in a net overall increase to each rifle of approximately one ounce in weight. All test firing was performed at 91.44 cm (100 yards). The rifles were cooled every nine rounds when fired with standard calibers and every six rounds when fired with magnum calibers. The results are set forth in TABLE I. ACCURACY TESTS Positions Shot/Index Reading Sweet Spot GROUPS Rifle Caliber Ammunition No BOS BOS A 30-06 Fed. 150 gr. 0 thru 10 10 1.453 .546 Win. 220 gr. 0 thru 6 4 - .252 B .270 Win. Fed. 130 gr. 0 thru 8 1 1.447 .441 Fed.P. 150 gr. 0 thru 7 7 1.571 .183 C .300 Win.Mag. Fed. 180 gr. 0 & 1 1 1.698 .190 Win. 220 gr. 1 1 1.951 .404 D 7 mm Rem. Mag Fed. 150 gr. 5 5 1.174 .149 Fed.P 165 gr. 0 0 1.238 .342 Horn. 175 gr. 3 3 - .489 E 22-250 Fed. 40 gr. 1 thru 9 3 .972 .280 Win. 52 gr. 1 thru 8 4 1.191 .171 F .338 Win. (BAR) Fed. 210 gr. 0 thru 9 7 3.9 .654 Fed. 250 gr. 0 thru 10 3 - .894 It was observed that a single full turn of the adjustable weight element 60 and thus also plug/weight 66 can cause a shot group to spread by as much as one inch, or more. In obtaining the data for Table I, the positions shot were at full turn markings on the scale 57 of the BOS. Microadjustments, less than one full turn, were not tested, but based on the test results obtained it is apparent that even tighter groups can be obtained after smaller incremental changes are made to the position of the adjustable weight element 60 and plug/weight 66. A significant recoil reduction was obtained using the BOS. Time/force curves were generated for each rifle tested and peak recoil reduction percentages obtained are as set forth in TABLE II. RECOIL REDUCTION Rifle Caliber Ammunition % Reduction A 30-06 Fed. 150 gr. 34% B .270 Fed. 150 gr. 25% C .300 Win. Mag. Rem. 180 gr. 31% D 7mm Rem. Mag. Rem. 175 gr. 33% E 22-250 Rem. 55 gr. 48% F BAR .338 Win. Mag. Fed. 250 gr. 34% As previously noted, most muzzle brakes heretofore available result in a very noticeable increase in noise and noise concussion to the marksman. TABLE III reports sound test results of rifles fired both with and without the BOS installed. Sound values are given in decibels. The noise meter used was placed identically with respect to the muzzle of each of the tested rifles. SOUND TESTS BOS POSITION Rifle Caliber Ammo. No System O 5 10 A 30-06 Win. 180 gr. 101.50 102.50 102.00 101.50 B .270 Win. Fed.P. 130 gr. 102.50 102.50 102.00 102.00 C .300 Win. Mag. Rem. 180 gr. 102.00 103.75 102.00 103.50 D 7mm Rem.Mag. Fed. 165 gr. 101.75 101.75 101.50 101.25 E 22-250 Rem. 55 gr. 101.00 101.50 100.75 101.50 F .338 Win.Mag. Fed. 210 gr. 102.25 103.25 102.00 103.00 From TABLE III it can be seen that only minor variations in sound volume occured in test firings of the rifles without the BOS and the rifles after the BOS had been added. In the few instances where a slight increase in sound was measured, it was not discernable to the marksman. Figure 6 illustrates a muzzle brake element 88 incorporating a preferred exhaust port arrangement which assures impingement of the emissions from aligned exhaust ports. The specifically illustrated pattern positions radial bores 90 in a first row and similar radial bores 92 in a second row, the two rows being approximately parallel with individual bores 90 radially offset, as shown, from individual bores 92. A third set of exhaust ports 94 is arranged in a third row approximately parallel the rows defined by bores 90 and 92, respectively. The individual ports 94 are aligned with respective individual bores 90 in a fashion which assures that the discharge from each port 94 impinges upon the discharge from the adjacent aligned bore 90. As illustrated, the paired ports 94 and bores 90 are aligned parallel the axis 96. A fourth row of ports 98 is arranged in similar paired arrangement with respective bores 92. Thus, the discharges from respective ports 98 impinge upon the radial discharges from corresponding paired individual bores 92. The illustrated and equivalent arrangements provide good muzzle break characteristics without an appreciable increase in discharge noise. While preferred embodiments of the invention have been disclosed, it is intended that the invention be limited only by the appended claims, including reasonable equivalents.

Claims: Method for optimizing the firing accuracy of a rifle being charged with a particular amunition type, characterized in that it comprises the mounting of an axially displaceable weight element (24,60) on the barrel (11,51) of the rifle, near its muzzle (14) and adjustably positioning of said weight element (24,60) on the barrel (11,51) in a position depending on the particular amunition type in order to dampen the vibration. Method according to claim 1, characterized in that it includes releasably locking said weight element (24,60) against further movement toward and away from said distal end (15,54) of said barrel (11,51), at a selected position on said barrel (11,51) by means of releasable locking means (16,55). Method according to claim 2, characterized in that it includes indicating, by means of indicator means (20,57), the position of said weight element (24,60) relative to said distal end (15,54) when said weight element (24,60) is locked against further movement toward and away from said distal end (15,54) of said barrel (11,51). Method according to claim 2 or 3, characterized in that a tubular weight element (24,60) is used which comprises interior threads (25,62) and mounting said weight element (24,60) on said rifle barrel (11,51) comprises screwing the weight element (24,60) on said barrel (11,51) which is provided with exterior threads (12,53). Method according to claim 4, characterized in that releasably locking said weight element (24,60) against further movement toward and away from said distal end (15,54) at a selected position comprises threading a lock nut (16,55) threaded onto said barrel (11,51) and engaged by said weight element (24,60). Method according to claims 3 and 5, characterized in that indicating said position of said weight element (24,60) relative to said distal end (15,54) when said weight element (24,60) is locked against further movement toward and away from said distal end (15,54) is made by a linear scale (20,57) having equally spaced indices formed on said barrel (11,51) and means carried by said lock nut (16,55) and forming an indicator cooperating with said indices. Method according to claim 6, characterized in that said indicating said position of said weight element (24,60) comprises the use of means carried by said lock nut (16,55) and forming an indicator, which means comprises a skirt (18,56) projecting from said lock nut (16,55) and telescoping over a portion of said barrel (11,51) and having an edge forming an indicator cooperating with said indices. Method according to any one of claims 4 to 7, characterized in that a weight element (60) is used which includes a portion extending beyond said distal end (54) of said barrel (51) and provided in its wall with spaced apart ports (68,69). Method according to either one of claims 1 to 8, characterized in that it includes removably securing an additional weight (66) to said weight element (60). Method according to claim 9, characterized in that securing an additional weight (66) comprises screwing said plug/weight (66) provided with a bore (72) therethrough to an end of said tubular weight element (60) which is provided with interior threads. Method according to claim 10, comprising using a lock washer (63) surrounding threads (53) on said barrel (51) and between said lock nut (55) and said tubular weight element (60) and a lock washer (67) surrounding threads on said plug/weight (66), between said plug/weight and said tubular weight element (60). Method according to claims 5 or 6 or 7, characterized in that releasably locking said weight element (24,60) comprises using a lock nut (16,55), the threads (25,62) of which cooperate with threads (13,53) on said barrel (11,51) in such way that one full rotation of said lock nut (16,55) relative to said barrel (11,51) moves said lock nut (16,55) axially along said barrel (11,51) a distance equal to the spacing between adjacent indices on said barrel (11,51). Method according to claim 7, characterized in that indicating the position of said weight element (24,60) comprises the use of another linear scale (22,59) having equally spaced indices around said skirt (18,56) of said lock nut (16,55) adjacent to said edge. Method according to claim 8, characterized in that a tubular weight element (60) is used which is provided with rows of ports (68) having each a central axis extending normal to the axis of said barrel (51) and encircling the wall of said tubular weight element (60) and a row of ports (69) each having a central axis extending at an angle of twenty degrees to said axis of said barrel (51) and encircling the wall of said tubular weight element (60).

Inventors: ROSE CLYDE E, ROSE, CLYDE E.
Applicants: BROWNING SA, BROWNING S.A.
Application year: 1993
Main classification: F41A21
IPC codes: F41A21, F41C27