WATER RESISTANT SHOT WAD

Abstract: A water resistant shotshell (10) has an internal moisture seal (32, 86) to preclude moisture intrusion into the propellant charge (26). The seal is at least one flexible tapered lip (32, 86) on the plastic shot wad (12) which is compressed against the inside surface of the shotshell tube over the powder charge. The preferred embodiment is a two piece shot wad having a shot cup portion (22) and a wad portion (24). The wad portion (24) has a central disk portion (28) and a tubular rim (30) terminating in a pair of opposing flexible lips (32) which provide a dual moisture seal.

Description: WATER RESISTANT SHOT WAD This invention generally relates to shotshells and more particularly to a water resistant shot wad/shot cup, and preferably to such a wad/cup for steel shot loads. 5 Shotshells for water fowl hunting have increasingly utilized steel shot loads to avoid the alleged toxicity problems claimed to be associated with lead shot. Waterfowl hunting is normally done near the water. Duck hunting is normally done from a duck blind 10 or a boat and often in wet conditions. Accordingly, it is not unusual for shotshells to get wet during waterfowl hunting. One of the banes of waterfowl hunters is wet shotshells which fail to function properly due to wet powder. One manner in which wet 1 5 powder can occur is by water penetrating the shotshell fold crimp, passing between the shot cup and the shell, then between the over-powder-cup and the shell and eventually reaching the powder charge. Conventional shotshells, such as are described in 20 U.S. Patents Nos. 3,289,586; 3,469,527; 3,623,431; 3,670,650; 3,788,224; 4,220,090; 4,233,903; 4,669,385; 4,676,170; and 4,679,505 have over powder wad columns which are not waterproof or water resistant. The over powder wad is designed to provide adequate pressure » 25 sealing against forwardly directed pressure acting ■^ against the rear of the wad due to the ignition gases , but is not effective to seal against low pressure rearwardly flowing water or high humidity gas entering from the front of the wad column. One solution, for moisture exclusion in roll crimped shotshells, is to provide a sealing top wad over the shot cup as in described in U.S. Patent No. 5,138,950, assigned to the assignee of the present invention. Another is to provide a thermoplastic seal over the top of the star or roll crimp as described in U.S. Patent No. 4,991,512, also assigned to the assignee of the present invention. From a manufacturing point of view, it would be more desirable to provide a moisture seal which is integral with a component that normally will be installed in the shotshell such as an over powder wad or shot cup to eliminate the necessity for providing an additional component to the shotshell. In addition, from a shooter's standpoint, it is preferable to seal from behind the shot so as to avoid having any extra components in front of the shot which might interfere with the shot patterning or clog gas ports of semi-automatic shotguns. However, there is no existing shotshell which has this ability to any degree of reliability, and reliability is of overriding concern to hunters who do not want to miss their target on account of ammunition failures. Accordingly, it is an object of the present invention to provide a reliable moisture seal behind the shot load, preferably a seal which is integral with the shot wad so as to eliminate the necessity for extra components. The shotshell in accordance with the present invention includes a plastic shot wad having a cup shaped over powder portion terminating in an annular, outwardly extending flexible lip having an outer diameter greater than the inside diameter of the shotshell case into which it is installed over the powder charge. This is applicable whether that tube is an injection molded tube, a compression-formed tube or reifenhauser-for ed tube. This flexible, resilient lip, compressed by the inside surface of the shotshell wall, provides a reliable moisture seal against water leakage past the shot column into the powder chamber. The shot column in accordance with the present invention may also include a shot cup which is either separate from, interengaged with, or even integral with the shot wad of the invention. The moisture sealing capabilities are further enhanced in the preferred embodiment by incorporating a second annular outwardly extending flexible lip above the lower lip. The sealing is even further enhanced by making this second lip project outwardly and upwardly to a greater diameter than that of the shot cup wall. Still further enhancement is preferably provided by causing the shot cup and over-powder wad to be separate yet interengaged by mating camming surfaces which tend to force the second lip outwardly into increased engagement with the inner wall of the shell case. In this last case a two piece shot cup and wad is utilized. Figure 1 is a side elevational view of a shotshell in accordance with the present invention with portions broken away to illustrate the shot wad in accordance with a first preferred embodiment of the present invention. Figure 2 is a longitudinal sectional exploded view of the wad portion and shot cup portion shown in Figure 1. Figure 3 is a longitudinal sectional exploded view of a second embodiment of a two piece shot wad and cup in accordance with the present invention. Figure 4 is a longitudinal sectional view through a third embodiment of the shot wad in accordance with the present invention. A shotshell 10 using a shot wad in accordance with the first embodiment of the present invention is shown in Figure 1. Figure 2 shows the wad and cup portions of the shot wad separate from the shotshell 10. Referring now to Figure 1, shotshell 10 has a metal head 14 enclosing a basewad and primer (not shown) closing one end of the reifenhauser tubing 16. The other end of the tube 16 is closed by a conventional star crimp 18. Crimp 18 of shotshell 10 encloses a load of shot 20 inside the cup portion 22 of the shot wad 12. Beneath the shot cup portion 22 is a wad portion 24 followed by a propellant charge 26. Referring now to Figure 2, the shot wad 12 in accordance with the first embodiment of the present invention comprises a generally tubular cup shaped shot cup portion 22 and an over powder wad portion 24. Wad portion 24 has a central domed disk portion 28 which terminates in a tubular rim 30. Rim 30 has a diameter of about 15 thousandths i.e. .015 inches less than the inside diameter of the reifenhauser tubing 16, which, for a 12 gauge shotshell, is approximately .744 inches. The tubular rim 30 terminates in annular upper and lower lips 32 which extend and taper outwardly from rim 30 to a diameter of from about .010 to .015 inches greater than reifenhauser tubing internal diameter. Accordingly, lips 32 have an outer diameter of about .755 inches. The tapered lips 32 are compressed into engagement with the inside surface of the tube 16 when the wad portion 24 is inserted into the shotshell 10. Insertion of the wad portion 24 into the tube 16 is assisted by use of an axially internally ridged bushing through which the wad portion is pressed to temporarily resiliently, partially compress the lips 32 of wad portion 24 to form grooves with a diameter between .030 and .035 inches less than the wad's free diameter prior to insertion of the wad into the reifenhauser tube 16. Temporary compression of lips 32 allows air pass the wad during assembly to prevent air being trapped under the wad portion. The wad portion is then inserted into the reifenhauser tube 16, allowing trapped air in the tube 16 to be released as the wad portion is inserted. The wad portion 24 then relaxes to its original diameter of about .729 inches, with the lips 32 compressed and resiliently biased against the inside surface of the reifenhauser tube 16. The lips 32 provide a dual moisture seal against moisture intrusion because both the upper and lower lips 32 are resiliently compressed against the inside surface of the reifenhauser tube. The upper surface 34 of the central disk portion 28 of the wad portion 24 has a dome shape to nest within a concave bottom 36 of the shot cup portion 22 inside the reifenhauser tube 16. In addition, the bottom 36 has a tapered outer margin 38 which acts as a rearwardly tapered outer camming surface 39 which matches and accommodates a corresponding inner forwardly flared camming surface 41 on the upper portion of the rim 30 of the wad 24 when the shot cup and wad portions are nested together. These matching camming surfaces 39 and 40 also assist in proper alignment of wad portion 24 and shot cup portion 22 during assembly of the shotshell 10. Similarly, the bottom surface 40 of the central disk portion 28 has a downwardly convex surface and a tapered outer margin and thus an overall cup shape over the powder chamber. This cup shaped surface, against which the gases generated by the propellant charge 26 press and expand upon charge ignition, produces an adequate gas seal between the wad and the reifenhauser tubing 16 and between the wad and the gun barrel during acceleration of the shot charge through the barrel and out the muzzle of the shotgun. The wad portion 24 is symmetrical about its actual axis. It is preferably also symmetrical in cross section about its central transverse axis so that assembly does not involve a determination of orientation. That is, the top side and bottom side of the wad portion are preferably identical so that the wad portion 24 is just as effective if inserted upside down. A second embodiment of the shot wad assembly of the present invention is shown in Figure 3. In the second embodiment, a two piece shot wad assembly 50 comprises a tubular closed bottom shot cup portion 52 and a wad portion 54. The bottom 56 of the shot cup portion 52 has a central, flat, disk portion 58 surrounded by an annular channel 60. Bottom 58 also has a tapered outer margin 62. The wad portion 54 is an axially and transversibly symmetrical circular, generally disk shaped body having a central flat disk portion 64 with a central axial bore 66. The disk portion 64 has a tubular rim 68 and a pair of tubular flanges 70 extending in opposite axial directions from the central disk portion 64 and spaced inwardly from the tubular rim 68. The tubular rim 68 of the wad portion 54 has flexible resilient tapered lips 72 extending outward from the upper and lower ends of the tubular rim 68. The lips 72 operate identically as described in the first embodiment. When the shot wad 50 is assembled together, the tubular flange 70 fits within the channel 60 in the bottom 56 of the shot cup 52. Outer margin 62 fits in between flange 70 and rim 68. This arrangement provides a tortuous leakage path and thus a good seal against combustion gas leakage through bore 66. This tortuous path extends from bore 66 past tubular flange 70 tapered margin 62, and lip 72 to the outside of the shot cup portion 52 thus precluding gas leakage during propellant ignition. The symmetrical design of the wad portion 54 enables orientation independent insertion of the wad into the shotshell case after having been precompressed as described in the first embodiment. In this second embodiment, it is not necessary to precompress the wad portion 54 by passing it through a bushing. The central bore 66 permits the escape of trapped air as the wad portion 54 is inserted in the tube 16 over the powder charge 26. The cup portion 52 is then inserted along with the shot load and seated against the wad portion 54. Finally, the open end 18 of the shotshell is conventionally crimped. A third embodiment of the shot wad in accordance with the present invention is shown in Figure 4. In this embodiment, shot wad 80 is a unitary body having an upper tubular cup portion 82 and an integral over powder cup portion 84 which terminates in an outwardly extending annular flexible, tapered lip 86 which functions identically to the lips 32 and 72 in the first two embodiments described above. However, in this embodiment the upper lip is dispensed with. The moisture seal is effected by the resilient lip 86 pressing outwardly against the inside surface of the reifenhauser tube 16. As in the first two embodiments, lip 86 has an outer diameter about 10 to 15 thousandths greater than the inside diameter of the reifenhauser tube 16. Compression of the wads in the first embodiment by passing the wad through a bushing, causes the high or low density polyethylene wad to remain compressed when it is released from the bushing for a period of time called its "relaxation time". This relaxation time is on the order of several minutes, during which time the wad slowly returns to its original uncompressed diameter. During this period immediately following compression in the bushing, the wad is inserted into the shotshell over the charge of propellant powder and seated at an appropriate distance from the base wad to enclose the propellant charge 26. Following insertion of the wad 24, 54, or 80, the shot cup 22 or 52 is inserted along with the required load of steel shot. Finally, the end 18 of the shotshell is closed in a star crimp or roll crimp in a conventional manner. Referring back to Figures 1 and 2, the first embodiment of the shot wad in accordance with the present invention has been extensively immersion tested as indicated by Tables 1, 2 and 3 set forth below. Table 1 represents pressure, velocity and pattern data for test lots of 10 shotshells each of 12 gauge, 3 inch shotshells with 1 1/4 ounce of BB steel shot. The first entry in Table 1 is the control, utilizing a conventional one piece yellow steel shot wad. The second and third entries, which have the two piece shot wad 12 in accordance with the present invention, exhibit a velocity and pressure similar to the control. In addition, the two piece shot wad lots demonstrate a comparable if not an improved shot pattern. Table 2 sets forth the results of a submergence test on identical Winchester® 3", 1 1/4 oz., steel shotshells which include two piece shot wads in accordance with the first embodiment of the invention. The cup portions were high density polyethylene (HDPE) and the wad portions were either HDPE or low density polyethylene (LDPE) . In these tests, the shotshells were soaked in water for a period of 24 hours and then allowed to stand in air at 70°F for periods of 1,3 and 7 days. As can be seen, water entered the shot cup, as evidenced by the weight gain, but did not enter the powder chamber. Velocity and pressure performance was similar to that shown in Table 1. There were no squibs, misfires, or other firing defects. In contrast, Table 3 gives the water test results for standard Remington® and Federal® production shotshell. In all test cases, the primer pockets were sealed with lacquer. Note that with submergence in water for only 16 hours, there were a total of 10 misfires, an entirely unacceptable performance due to moisture entering the propellant chamber. TABLE 1 PRESSURE AND VELOCITY AND 30" CIRCLE PATTERN DATA - 2 PIECE SHOT WADS SYMBOL XSV1Z3BB (12 GA. 3" 1 1/4 OZ. BB STEEL) HAD TYPE 1 Piece Yellow 2 Piece SS. 2 Piece S.S. 1 1/4 oz (Control) /LDPE P.C. w/HDPE P.C. PROPELLANT HERC 378-006 HERC 378-006 HERC 378-006 g»33.0 gr. §33.0 gr. 34.0 gr. SHOT 549 gr. 549 gr. (91 Pellets) (91 Pellets) 70 +125 0 70 +125 0 10 10 10 20 20 20 109 104 117 109 109 118 118 108 124 118 109 128 101 99 110 100 93 108 5.4 2.9 5.5 4.5 4.6 7.0 79.7 81. 11 10 4.2 3.6 86. S 88.3 91 94 79 83 4.6 4.6 TABLE Z HATER TEST RESULTS - Z PIECE STEEL SHOT WADS <N=20) 24 24 24 1 3 7 0 0 0 0 0 0 1330 1341 1335 1356 1380 1362 1309 1319 1297 14 15 17 TABLE 3 HATER TEST RESULTS HITH PRESSURE & VELOCITY DATA 12 GA. Z 3/4" 1 1/4 OZ. STEEL SHOT LOADS N=20 SAMPLE Control Federal/W148 Remington for STL 125 Meg. One Piece Had One Piece Had Steel Shot Sheet Shot PROPELLANT HERC 205 HERC 370 HAD COLUMN (std. prod. IX." (std. prod. U" steel shot wad) steel shot wad) 6 seg. C.F. 6 seg. C.F. STORAGE TIME HOURS IN H 2 0 0 21 21 21 21 0 21 21 21 21 DAYS IN AIR @ 70° 21/24 0 1 2 7 21/24 0 1 2 7 WATER HT. GAIN AVG. 0 3.6 4.6 4.1 7.1 MAX. 0 7.2 7.6 7.9 21.8 MIN. 0 1.8 1.7 1.9 1.7 FIRING DEFECTS SQUIB. MISFIRE. OFFSOUND VELOCITY (FT/S) AVG. 1277 1242 1218 1158 1123 1264 1112 767 589 981 MAX. 1292 1279 1248 1202 1181 1307 1216 1083 1054 1148 MIN. 1255 1188 1150 1107 1016 1225 987 425 332 704 STD. DEV. 11 26 31 29 46 28 68 255 266 165 113 108 90 90 125 122 103 113 95 91 78 70 10.4 8.2 7.7 12.5 As can be seen by comparing Tables 2 and 3, the shot wads in accordance with the present invention preclude entry of moisture into the powder chamber of the shotshell. This improved seal is due to the presence of the outwardly extending lips 32 which compressively engages the inside wall surface of reifenhauser tubing 16. Although moisture does get into the shot column, as illustrated by the water weight gain set forth in Table 2, little effect is seen on performance, velocity, and pressure. While the invention has been described above with reference to specific embodiments thereof, it is apparent that many changes, modifications, and variations can be made without departing from the inventive concept disclosed herein. Accordingly, it is intended to embrace all such changes, modifications, and variations that fall within the spirit and broad scope of the appended claims.

Claims: WHAT IS CLAIMED IS: 1. A shotshell wad (12) characterized by a cup portion (22) adapted to contain a load of steel shot and a wad portion (24) adapted to be positioned between the cup portion and a propellant charge (26) of a shotshell (10), the wad portion having at least one resilient outwardly flared lip (41) extending outwardly therefrom compressed against an inside surface of the body to form a seal against moisture intrusion into the propellant charge. 2. The shotshell wad according to claim 1 characterized in that the lip (32) is a tubular extension of the wad portion. 3. The shotshell wad according to claim 1 characterized in that the tubular extension (32) is also tapered so as to increase its flexibility. 4. The shotshell wad according to claim 1 characterized in that the flared lip (32) extends outward to a diameter greater than the maximum diameter of the remainder of the shot wad. 5. The shotshell wad according to claim 4 characterized in that the shotwad contains at least two flared lips (32) . 6. The shotshell wad according to claim 5 characterized in that the two flared lips (32) are flared in the same direction. 7. The shotshell wad according to claim 5 characterized in that the two flared lips (32) are flared in opposite directions. 8. The shotshell wad according to claim 1 characterized in that the shot wad comprises a separate cup portion (22) and wad portion (24). 9. The shotshell wad according to claim 8 characterized in that the cup portion and wad portion have interengaged camming surfaces (39, 41) for helping to force the flared lip outwardly into sealing engagement with the shotshell body. 10. The shotshell wad according to claim 9 characterized in that the cup portion has an outer rearwardly tapered camming surface (38) and the wad portion has a matching inner upwardly flared camming surface. 11. The shotshell wad according to claim 10 characterized in that the camming surface (41) of the wad portion is adjacent the flared lip (32). 12. The shotshell wad according to claim 11 characterized in that the wad portion has identical forward (34) and rearward (40) surfaces whereby to prevent any adverse effect from inversion of the wad portion during assembly of the shotshell. 13. The shotshell wad according to claim 2 characterized in that the wad portion has a central disk portion (28) and a tubular rim (30), the tubular rim terminating in a pair of oppositely directed tapered lips (32). AMENDED CLAIMS [received by the International Bureau on 13 January 1994 (13.01.94); original claims 1-5,8,9 and 12 amended; other claims unchanged (2 pages)] 1. A shotshell wad (12) characterized by a cup portion (22) and a wad portion (24) , the wad portion (24) having at least one resilient outwardly flared lip (41) extending outwardly therefrom which when compressed against an inside surface of a shotshell wall forms a seal against moisture intrusion into a propellant charge. 2. The shotshell wad according to claim 1 characterized in that the lip (32) is a tubular extension of the wad portion which is resiliently biased against the shotshell wall. 3. The shotshell wad according to claim 2 characterized in that the tubular extension (32) is tapered to increase flexibility. 4. The shotshell wad according to claim 2 characterized in that the lip (32) fiares outwardly to a diameter greater than the maximum diameter of the remainder of the wad portion. 5. The shotshell wad according to claim 4 characterized in that the wad portion contains at least two flared lips (32) . 6. The shotshell wad according to claim 5 characterized in that the two flared lips (32) are flared in the same direction. AMENDED SHEET (ARTtbLE 19) 7. The shotshell wad according to claim 5 characterized in that the two flared lips (32) are flared in opposite directions. 8. The shotshell wad according to claim 2 characterized in that the shotshell wad cup comprises a separate cup portion (22) and a wad portion (24) . 9. The shotshell wad according to claim 8 characterized in that the cup portion and the wad portion have interengaged camming surfaces (39, 41) for helping to force the flared lip outwardly into sealing engagement with the shotshell wall. 10. The shotshell wad according to claim 9 characterized in that the cup portion has an outer rearwardly tapered camming surface (38) and the wad portion has a matching inner upwardly flared camming surface. 11. The shotshell wad according to claim 10 characterized i that the camming surface (41) of the wad portion is adjacent the flared lip (32) . 12. The shotshell wad according to claim 11 characterized i that the wad portion has identical forward (34) and rearward (40) surfaces to prevent any adverse effect from inversion of the wad portion during assembly of the shotshell. 13. The shotshell wad according to claim 2 characterized in that the wad portion has a central disk portion (28) and a tubular rim (30) , the tubular rim terminating in a pair of oppositely directed tapered lips (32) . STATEMENT UNDER ARTICLE19 The International Search Report cited the following documents against Applicant's claims: U.S. 3,402,664 (Cramer); U.S. 3,786,753 (Eckstein et al) ; U.S. 4,815,389 (Jakonczuk) ; FR 2,343,219 (Pregay) ; and U.S. 3,022,734 (Kidder) . Applicant's invention is drawn to a shot wad cup designed to prevent water from contacting the propellant charge. This is accomplished by providing the wad cup with outwardly flared lips which compress against the inside surfaces of a shotshell wall in a resiliently biased manner. The documents considered in the International Search Report disclose many shotshell wad cups effective to prevent the escape of reaction gases following ignition of the propellant. This is not analogous to shotshell wad cups for preventing the ingress of low pressure water. As disclosed in Applicant's specification at page 1, lines 23-29, shotshell wad cups which provide adequate high pressure gas sealing may not be effective to seal against low pressure rearwardly flowing water. As a result, one skilled in the art would not be lead to the conclusion that a shotshell wad cup effective as a sealant of high pressure gas would have utility as a sealant against low pressure water ingress. More specifically, U.S. 3,402,664, discloses a one piece shot wad having a shot cup with rearward lips that are flared to provide a tight seal to prevent ignition gas escape. The shot wad is formed from polyethylene. There is nothing in the reference to teach or suggest biasing the lips to provide a seal effective to prevent the ingress of water. U.S. 3,786,753 discloses a shot wad having a tapered cup and rearward lips. A small indented shot cup extends forwardly from the shot wad. There is nothing in the reference to teach or suggest an arrangement effective to prevent the ingress of water. U.S. 4,815,389 discloses a shot wad having two cups with outwardly flared lips extending in opposing directions. While the lips are effective to provide a gas seal, there is nothing to teach or suggest an effectivness of the lip to prevent the ingress of water into the propellant charge. FR 2,343,219 discloses a two piece shot wad effective to form a gas seal. U.S. 3,022,734 discloses a shotshell wad having two sets of oppositely directed tapered lips. While these lips may be effective to form a seal to prevent the escape of high pressure gas, there is nothing in the combination of FR 2,343,219 and U.S. 3,022,734 to teach or suggest a means to prevent the intrusion of moisture into a propellant charge. Entry of this amendment under PCT Article 19 is respectfully solicited. It is believed that when the authorized Officer considers the amended claims and these remarks, an affirmative statement will be issued with the written opinion. If the authorized Officer requires any additional information, he is invited to contact Applicant's attorney at the telephone number listed below.

Inventors: GARDNER ROBERT J, GARDNER, ROBERT, J.
Applicants: OLIN CORP, OLIN CORPORATION
Application year: 1993
Main classification: F42B7
IPC codes: F42B7