Abstract:
A recoil converter for reducing the recoil shock of a gun by up to 95 percent is provided with a gun stock prepared to have a shorter length at its rear end by about 1 1/2″ from the intended overall length, a middle bore and two guide holes. A mixed gas chamber absorbs most of the recoil from shooting by having a hybrid tubular body of a stainless steel midsection and an aluminum head and tail sections welded together. The head section has a central hole for receiving a threaded plug to close and adjust the interior volume of the chamber under gas pressure and a side gas port for controllably injecting a predetermined amount of the mixed gas with the plug shifted behind the gas port. A plunger of the gas chamber takes the recoil into the pressurized interior volume.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    A. Field of the Invention 
         [0002]    The present invention relates to a gun. More particularly, the present invention relates to an improved recoil converter for eliminating major recoil action in place of factory installed recoil reducers. 
         [0003]    B. Description of the Prior Art 
         [0004]    Factory rifles necessarily have a stock at the shooter&#39;s end. Stocks are made of solid wood, plastic or metal form to give a firm hold by the shooter at the shoulder area. Soft recoil pads or butt pad were attached to the end walls of the stock to buffer the after effect of firing the rifle with an explosive launch of a bullet. To counter the recoiling forces and find the softest way of shooting, many recoil reducers were suggested to assist the pads for absorbing the unpleasant if not unhealthy reactions at firing the guns. Different shock absorbers have been adapted to make gun buffers to reduce the felt recoil. Some of them came in the form of a hydraulic cylindrical recoil buffer that looks like a miniaturized door buffer used for various applications. Others include a recoil tube with a mechanical steel spring inside. 
         [0005]    U.S. Pat. No. 3,039,222 to Hoge describes three pistons with a middle gas chamber. It has mounting screws that are co-axial to the piston rod. It also has a chamber stock attachment plate and a gas for shock absorption. The side pistons function as stabilizing guide. 
         [0006]    U.S. Pat. No. 1,964,649 to Stetson provides a middle compression area that is backed up by a spring. It also has two side stabilizing guides and a backing plate. 
         [0007]    Therefore, the purpose of the present invention is to provide a device to convert the felt recoil of the hard-hitting factory recoil systems into a negligibly mild, soft, and comfortable tap. 
       SUMMARY OF THE INVENTION 
       [0008]    Sportsmen and any other persons who are respectable and ethical shooters can receive the benefit of the inventive recoil converter incorporated into the existing guns and rifles. In the center of the recoil converter is a gas-operated chamber that is activated by the firing of the shotgun or the rifle. The converter also incorporates one and one half inches of controlled travel while not affecting the performance or the accuracy of the shotgun or rifle. 
         [0009]    The claimed recoil reduction by the recoil systems in practice on the current market is at best 50% indicating an elimination of the recoil has been impossible simply by mental trials with better looking designs but extensive performance tests to reach the ultimate combination of material, mechanics and dimension. The present invention now introduces such a recoil device to convert the guns in existence to provide a felt recoil reduction by an unprecedented 95% in the field. The 95% reduction means a pleasant shoulder tab replaces the recoil pain. For a lot of individuals with shoulder impairment, regaining the ability to hold guns in need may be important to have confidence in life. Also attained is a leap in the performance of each individual&#39;s own best gun. The recoil converter of the present invention permits longer practice in the field, improves the qualities of the outdoor activity with gun for hunting or simply sharpening one&#39;s shooting skills. 
         [0010]    The recoil converter of the present invention is constructed from a lightweight aerospace plastic, a durable aluminum chamber and stainless steel guide rods. The gas filled chamber reacts to the firing of the weapon by transforming the force into a graduated reduction by using the travel incorporated into the converter. 
         [0011]    According to the present invention, a recoil converter for reducing the recoil shock of a gun by 95 percent comprises a gun stock having generally oval cross sections of varying areas and its length shorter at its rear edge by about 1 ½″ from the intended overall length; a middle bore having a diameter on the order of 1″ extending about 4 ⅛″ deep; two guide holes positioned at both sides of and in line with the middle bore each having a diameter of ⅜″ extending about 2 ½″ deep; a mixed gas chamber having a hybrid tubular body of a stainless steel midsection and an aluminum head and tail sections welded together, the midsection having a majority of eccentric inner tubular wall with reference to the exterior wall of the gas chamber and a short concentric tubular wall with a stepped transition between them, the head section having a large central threaded through hole for receiving a threaded plug to close and adjust the interior volume under gas pressure in the gas chamber and a side gas port formed through the head section into the central through hole for controllably injecting a predetermined amount of the mixed gas with the plug shifted behind the gas port, the gas chamber having a plunger including a translating shaft passing through a bushing mounted inside of the tail section of the gas chamber and terminating at an outer end with an internally threaded bore and at the opposite end with an internal shaft for mounting a seal assembly consisting of at least two cup seals and at least a double quad seal for a pressurized translation through compression and expansion of the interior volume of the chamber by the seal assembly in response to the recoil shock and the tail section having an outwardly threaded mounting end; a main plate made of an aerospace grade plastic material machined to fit onto the end of the stock having a middle chamber mounting bore with a larger concentric nut relief for receiving the tail section of the gas chamber to fasten it with a hex jam nut and two guide holes positioned at both sides of and in line with the middle mounting bore corresponding in diameter and position to the respective guide holes of the stock so that upon fastening the main plate to the stock using two peripheral long screws the chamber body penetrates into the 1″ middle bore and the outer shaft extending rearward from the surface of the main plate; a shoulder attachment plate made similar to the main plate in material and shape having two stabilizer guides mounted by forward driven screws at the corresponding positions to the guide holes, the shoulder plate also having a middle shaft screw for operatively connecting the shoulder plate to the shaft of the gas chamber with 1 ½″ of distance to travel against the main plate and two peripheral screws backward driven to extend rearward of the shoulder plate; and a soft shoulder pad bearing against the shoulder of a shooter and shaped to fit the sides of the shoulder plate and fastened thereto by the backward driven peripheral screws of the shoulder plate. 
         [0012]    Embodiments of the invention will now be described by way of example with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a side elevational view of a recoil converter installed in a stock of a rifle according to the present invention. 
           [0014]      FIG. 2  is an exploded perspective view of the recoil converter of  FIG. 1  to show the respective components more clearly. 
           [0015]      FIG. 3  is a longitudinal cross sectional view of gas-operated chamber of the recoil converter of  FIG. 1  detailing the structure and proportion of the internal parts thereof. 
       
    
    
       [0016]    Similar reference numbers denote corresponding features throughout the attached drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]    With reference to  FIG. 1 , a recoil converter  10  according to the preferred embodiment of the present invention is adapted to replace an old recoil reducer or butt pad or any other gadgets mounted earlier but are short of providing a major reduction in the recoil shocks of a stock  12  at the rear end of a gun  14  that may be of any sizes and types involving a shoulder supported firing. The recoil converter  10  is shown in the drawing at rest before a recoiling travel that equals one and a half inches of controlled movement. The details for making the recoil converter is as follows. 
         [0018]    First, the recoil converter  10  is 11.4 oz in weight including a gas chamber  16  in the center and two side stabilizer guides  18 , all of which extend through a chamber/stock attachment plate  20 . The stabilizer guides  18  are made of  303  stainless steel into cylindrical rods each having a round tip and a flat rear end for the purposes as described below. 
         [0019]    The chamber/stock plate or main plate  20  is a solid structure made of one of aerospace grade plastics. Such a blank plate in a rectangular shape dimensioned 5 ½″×2″×0.375″ may be initially prepared so that it extends over most stock butts. The blank plate  20  after boring the required mounting holes weighs 2.8 oz. As better shown in  FIG. 2 , the main plate  20  is then shaped into an oval disc having a chamber mount bore  22  and a larger concentric nut relief  24  in the center sized to receive a hex jam nut  26  for fastening the chamber  16  onto the main plate  20  and two guide holes  28  for accepting the stabilizer guides  18 . Also drilled at the longer ends of the oval main plate  20  are screw holes  30  of for two long screws  32  for permanently fastening the plate  20  to the butt area of the stock  12 . The circumference of the plate  20  may be finished to conform exactly to the individual model of stock  12 . 
         [0020]    The best mode dimension of the described parts and areas in longitudinal length or diameter are as follows: 
         [0021]    Recoil converter  10 : 6 ¼″ 
         [0022]    Chamber mount bore  22 : DIA. 0.650″ 
         [0023]    Guide holes  28 : DIA. 0.375″ 
         [0024]    Long screw  32 : DIA. 1.500″ 
         [0025]    Stabilizer guides  18 : DIA. 0.375″ 
         [0026]    Jam nut  26 : thread DIA. ⅝-18 
         [0027]    Screw holes  30 : DIA. 0.192″ 
         [0028]    Referring to  FIG. 3 , the gas chamber  16  of the recoil. converter  10  has a cylindrical body comprising a main cylinder section  34  (2.739″-DIA. 0.750″) made of  304  stainless steel, a rear cylinder section  36  (1.367″) made of  76  series high strength aluminum alloy connected in line with a rear end  38  of the main cylinder section  34  and including a threaded mounting end  40  (0.375″-thread DIA. ⅝-18), and a chamber block  42  (0.339″-DIA. 0.750″/0.625″) made of 76 series high strength aluminum alloy connected in line with a front end  44  of the main cylinder section  34  and including a side gas port  46  (DIA. ⅛″ and 0.010″) and a port plug  47  threaded centrally through the chamber block  42  for opening and closing the port  46  in case a gas filling or discharging is necessary. When the gas chamber  16  is appropriately charged, it may be sealed externally using a sealant to cover the nooks and crannies of the whole chamber block  42 . At the proximal area of the threaded end  40 , a thread relief  48  (0.1875″) is formed. The main cylinder section  34  has a first inner tubular wall  50  that briefly extends concentric to its outer surface near the rear end  38  and a second inner tubular wall  52  that is expanded eccentrically from the first wall  50  with a circumferential step  54  formed between the two walls  50 ,  52 . Also, a backlash port  56  (DIA. 0.125″) is bored through the main cylinder section  34  near its junction with the rear cylinder section  36  to open a part of the inner chamber to the atmosphere. 
         [0029]    The gas chamber  16  also has a plunger comprising a shaft  58  (DIA. 0.250″) of  304  stainless steel, which may extend externally up to 1.500″ from the threaded end  40 . An internal thread  60  is formed at a rear end of the shaft  58  for mounting in the subsequent assembly of the recoil converter  20 . The shaft  58  also extends internally of the rear cylinder section  36  and is sleeved by an oil impregnated sintered bronze bushing  62 . Also connected integral to the front end of the shaft  58  are a retaining rod seal  64  of an enlarged diameter to limit the forward travel of the converter body sections  34 ,  36  relative to the shaft  58  and an internal shaft  66  of a reduced diameter extending concentrically of the shaft  58  beyond the backlash port  56  but terminating midway along the main cylinder section  34 . Attached to the front end of the internal shaft  66  is a seal assembly  68  to form and maintain a pressurized room  70  in association with the chamber block  42  while the other rear side of the seal assembly  68  is open to the atmosphere through the port  56  as described above. The seal assembly  68  comprises two U-shaped cup seals one  72  having an eccentric core post  74  made of metal or plastic and threaded through the other one  76  into the front end of the internal shaft  66 . In the space between the two cup seals  72 ,  74  a double quad seal  78  made of an elastomeric material is threaded. Quad seal  78  comprises an o-ring with an x shaped profile so that when squeezed upon installation, it seals with two small contact surfaces  80  on the top and bottom, respectively. 
         [0030]    For the purpose of assembly, the core post  74  of the cup seal  72  is dimensioned so that upon welding the chamber sections  34 ,  36  and  42  together the cup seal  76 , double quad seal  78  and cup seal  72  of the seal assembly  68  may be orderly introduced into the internal chamber  16  space through the chamber block  42  before placing the port plug  47 . By this sequence of assembly, the gas chamber  16  may be free of possible heat damage to the elastic seal assembly  68  due to the high welding temperature for making the metallic chamber sections. The gas chamber  16  is charged with mixed gas, which is non-toxic and non-flammable. A special charger is necessary to achieve a controlled filling as will be described below. Then, the seal assembly  68  may be threaded into the internal shaft  66  followed by screwing the port plug  47 . The main plate  20  is secured to the main body of gas chamber  16  using the hex jam nut  26 . 
         [0031]    Now, a quick and easy method to condition the factory stock  12  to accept the recoil converter  10  will be described. The stock  12 , shown with the factory recoil pad removed, is cut approximately 1 ½″ from the original rear edge to compensate at least the distance of travel of the recoil converter  10  to cover and then carefully drilled from the new edge to have 1″ DIA. middle bore  82  extending about 4 ⅛″ deep. If the stock already has a cylindrical rear bore with 1″ diameter, it can be bored further to extend 5″. Then, two ⅜″ DIA. holes  84  are formed on both sides of the middle bore  82  with a depth of about 2 ½″. 
         [0032]    To mount the main plate  20  on the stock  12 , the old screw holes should be filled with a substance that will then allow screwing in the new long screws  32 . A small wooden dowel rod (not shown) may be used for that purpose. They may be cut to size as glue is applied in the holes, into which the dowels are inserted. After the dowel is set the butt of the gun may be completely smoothed using a sanding device. Then, a template may be used for pre-drilling holes  86  for screwing in the recoil converter on the main plate  20  into the newly drilled holes  86 . After installation, shots become more accurate because the shooter is more relaxed. The tendency to hold the stock tightly to manually absorb the recoil will be eliminated since only 5% of the total recoil will be left to feel. Scientific testers were used to measure the effect objectively. Because of the precut one and a half inch length, the stock  12  will have no substantial difference in length before and after the installation of recoil converter  10 . After the cutting and boring, the stock  12  will replace approximately 5.8 oz of weight with the 11.4 oz of recoil converter  10  resulting in an additional weight of 5.6 oz to the gun  14 . 
         [0033]    Positioned rearward and in parallel to the main plate  20  is a shoulder attachment plate  90  made of an aero grade plastic similar to the one used for the main plate  20 . The similar plastic blank plate having a rectangular shape dimensioned 5 ½″×2″×0.250″ may be initially prepared to cut into an oval shape conforming the stock  12  and main plate  20 . The blank plate  90  after boring the required mounting holes weighs 2.0 oz. As better shown in  FIG. 2 , the shoulder plate  90  is positioned between the main plate  20  and a shoulder pad  92  to have the longitudinal shaft  58  of the gas chamber  16  transform into a latitudinal wide contoured area for effectively neutralizing most of the backward impact of the stock  12  at a gun firing. The shoulder plate  90  has multiple screw holes including a middle shaft hole  94  sized to accept an 8-32 screw  95  for fastening the shaft  58  to the shoulder plate  90  and two stabilizer holes  96 , which are aligned with the stabilizer receiving holes  84  of the stock  12  and sized to receive 8-32 or 10-32 stainless steel screws  98  for fastening the flat ends of the stabilizer guides  18 . The screw holes  94  and  96  have round relief areas for receiving the respective screw heads to join the opposing surfaces of the shoulder plate  90  and shoulder pad  92  over a perfect plane. Also, two threaded holes are formed close to the opposite ends of the shoulder plate  90  to accept 10-32 screws  100 , which secure the shoulder plate  90  and shoulder pad  92 . 
         [0034]    The best mode dimension of the described parts and areas in longitudinal length or diameter are as follows: 
         [0035]    Middle shaft hole  94 : DIA. 0.162″ 
         [0036]    Shaft screws  95 : thread DIA. 0.162″/0.600″ 
         [0037]    Stabilizer holes  96 : DIA. 0.162″ 
         [0038]    Stabilizer screws  98 : thread DIA. 0.162″/0.600″ 
         [0039]    Short screws  100 : thread DIA. 0.162″/0.600″ 
         [0040]    With the carefully machined components as above, three main steps of assembly will complete the installation of the recoil converter  10  to the gun  14 : the first subassembly of the main plate  20  and gas chamber  16  is attached by long screws  32  to the stock  12  followed by the second subassembly of shoulder plate  90  and the two stabilizer guides  18  being secured to the main plate  20  at the shaft  58  of the gas chamber  16 . Thirdly, the shoulder pad  92  is secured to the shoulder plate  90  by driving two short screws  100  backward through the shoulder  90  into the shoulder pad  92 . 
         [0041]    In operation, the gunstock  12  renovated according to the present invention substantially remains the same in extension and weight as the original structure except the functional clearance of the shoulder pad  92  from the stock  12 . The gun  14  made true to the specification above was tested to show the dramatic near perfection in recoil reduction. 
         [0042]    In manufacturing the effective recoil converter, a measured gas filling into the gas chamber and testing the actual performance of the chamber are of utmost importance. To this end, the present invention uses a digital force gauge with load cell manufactured by AMETEK located in 8600 Somerset drive, Largo, Fla. 33773 and sold under the Chatillon trademark and model No. DFS-R. The Chatillon® DFS-R Series is described as supplying accurate load measurement for capacities up to 1000 lbf, 5 kN. Ideal for handheld or test stand applications, measurement accuracy is better than 0.1% full scale. A large, easy-to-read, high resolution dot matrix LCD display supports a variety of standard gauge functions including normal and peak readings, high/low limits, set points, pass/fail results, statistical results, load averaging, load comparisons, % and sharp break detection, sensor actuation and direction. Measurements are displayed in ozf, gf, lbf, kgf and N units. The DFS-R gauge is also supplied with computer software. Thus, the gas chamber  16  of the present invention may be loaded in a charging station, where the load cell of the gauge is interposed between the shaft  58  of the gas chamber  58  and a lock-and-release arm for an accurate reading of the amount of gas in terms of foot-pound as compared to conventional PSI as it is injected from a gas tank through a cylinder work into the side gas port  46  leading to the pressurized room  70  of the gas chamber  16 . 
         [0043]    To heighten the quality of the recoil converter  10 , it is preferred that the gas charged chamber  16  be tested to insure the consistent recoil reduction before it is assembled into the converter product. At the next stage of chamber stroke testing, the gas chambers  16  are subjected to ten thousand simulated firings. The stroke stage may produce the actual firing of a shotgun or rifle. A particular gas chamber may pass the quality test only after this stroke stage. The tester is adapted to test ten gas chambers simultaneously incorporating an air compressor by employing a metered air plunger at the top to repetitively impact loaded gas chambers not pictured in the lower slots through the simulated main plate and shoulder plate. Each of the gas chambers may be visually checked after the operation of the tester for an insufficient extension of the shaft  58  so that the corresponding gas chamber may be taken to a troubleshooting or simply refilled with gas followed by another testing until it is in the perfect condition for installation on the customer&#39;s gun. 
         [0044]    Tests using the same stroke tester model CPST-4743 on a simulated shooter showed that each firing with a Remington Model 870 Shotgun equipped with the inventive recoil converter  10  averaged 168 foot-pound of felt recoil. 
         [0045]    Therefore, while the presently preferred form of the recoil converter has been shown and described, and several modifications thereof discussed, persons skilled in this art will readily appreciate that various additional changes and modifications may be made without departing from the spirit of the invention, as defined and differentiated by the following claims.