US3507220A - Ammunition round - Google Patents

Description

April 2l, 19.970 C. M, MCCLURE 1u AMMUNIT ION "ROUND 2 Sheets-Sheet 1 .lriginal Filed Nov. l5, 1967 INVENTOR CLIFTON M.` MCCLUREJII ATTORNEY C. M. MCCLURE Ill April 21, 1970 AMMUNIT I ON f ROUND I 2 Sheets-Sheet 2 Original Filed Nov. l5, 1967 INVENTOR CLIFTON MA MCCLURE DI ATTORNEY United States Patent O 3,507,220 AMMUNITION ROUND Clifton M. McClure III, 3510 Carroll Circle, Huntsville, Ala. 35801 Continuation of application Ser. No. 683,313, Nov. 15, 1967. This application Jan. 2, 1969, Ser. No. 789,661 Int. Cl. F42b 7/04 U.S. Cl. 102-42 3 Claims ABSTRACT OF THE DISCLOSURE An ammunition round which is gun-launched and gunboosted and which includes a self-contained rocket motor. Payload velocity is developed in two parts; the first part or increment is developed within the gun barrel under influence of a gun boost powder charge, followed by a gradual but large velocity increase beyond the barrel under ini-iuence of the rocket motor. The maximum accelerations to which the round is subjected are low in comparison to an ordinary shotgun, resulting in better shot charge patterns and less flattening and deformation of shot pellets.

CROSS-REFERENCES TO RELATED APPLICATIONS v This application is a continuation of application Ser. No. 683,313, tiled Nov. 15, 1967, now abandoned which in turn is a continuation-in-part of application Ser. No. 528,714, filed Feb. 21, 1966, also abandoned.

BACKGROUND OF THE INVENTION The need for the invention arises in connection with a variety of civilian and military weapons. In general, the art is constantly seeking to deliver heavier payload masses at higher target-plane energies and velocities with less recoil and gun barrel stress than is possible with ordinary shotgun techniques. It is also desirable to reduce muzzle blast effect to a substantial extent and to permit lighter gun construction. A more controlled delivery of the shot charge to a target is highly desirable, where the charge spread or pattern is not dependent on the muzzle of the gun. The prior art has not achieved these objectives to a satisfactory extent and it is the purpose of the invention to overcome the prior art deficiencies, particularly those enumerated, as well as additional factors which are not mentioned.

SUMMARY OF THE INVENTION The invention round embodies a head or casing containing a primer and a gun boost powder charge, both arranged rearwardly of a gun boost Wad structure having an ignition channel. Forwardly of the wad structure is the body portion of the round including a propellant charge and rearward rocket propulsion nozzle immediately forwardly of the wad structure and in alignment with the ignition channel. The body portion of the round separates from the head in the gun barrel and the head remains in the chamber While the body portion is propelled through the barrel and then down-range toward the target. The body portion may be provided with means to initiate spinning while within the barrel and to continue during the flight of the round toward the target or other means may be provided to render the round aerodynamically stable during flight. Spinning of the round, even at a relatively slow rate, greatly overcomes thrust misalignment from the rocket motor and increases stability. The payload is contained in a cavity at the leading end of the body portion for delivery to the target with maximum energy and velocity.

3,507,220 Patented Apr. 21, 1970 BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 6 is a similar view of the round showing release of the shot charge therefrom near the target;

FIGURE 7 is a fragmentary central vertical section through a round embodying a modification.;

FIGURE 8 is a similar view showing a further modification;

FIGURE 9 is a fragmentary side elevation of a round embodying another modification; and

FIGURES l0 to 12 inclusive are fragmentary vertical sectional views showing further modifications of the round.

DESCRIPTION OF THE PREFERRED EMBODlMENTS Referring to the drawings in which like numerals designate like parts, attention being directed first to FIGURES 1 through 6, the ammunition round is shown in its entirety in FIGURE l within a shotgun barrel 20 prior to tiring the round. As shown, the shotgun has the usual chamber 20a and forcing cone 2017 leading into the barrel bore 20c. The round, as shown, comprises a casing or head 21 formed of any conventional material such as plastic or metal and is received snugly in the chamber 20a like a cartridge or shell of known caliber. The casing 21 has the usual rim 22 to arrest forward movement in the chamber and is equipped centrally with a primer 23, ired by a suitable firing pin 24. Within the casing 21 immediately forwardly of the primer is a gun boost charge 25 of gun powder which is exploded upon firing the primer 23. Also =within the casing 21 forwardly of the gun boost charge 25 is the first section 26 of a preferably two-part gun boost wad having a second or forward wad section 27. In some instances, the wad structure may be formed in one piece from one or more distinct materials in lieu of the two section wad shown in the drawings. The wad section 26 preferably formed of plastic is primarily an obturating wad and ts tightly in the casing 21 and also in the gun barrel bore 20c as shown in FIGURE 4. The wad section 26 has a small central igniter bore 28 which also serves to limit the internal pressurizing of the rather fragile rocket body portion due to the high pressure gases produced by the explosion of the gun boost charge. This feature will be further discussed. The second wad section 27 is preferably formed of felt or the like and has a larger central igniter bore 29 formed therethrough which may be filled in some instances with an igniter powder or substance. This is an optional feature. The wad section 27 also has a tight tit in the casing 21 and bore 20c, as shown.

Forwardly of wad section 27 in abutting contact therewith is a nozzle block or element 30l having a central propulsion nozzle opening 31 which is in registry with igniter bore 29. The outside diameter of the element 30 is slightly less than the inside diameter of the casing 21 and the diameter of the -bore 20c. A reduced extension 32 on the nozzle element 30 is rmly secured telescopically to the rear f a rocket motor body or tube 33 formed of high strength paper or very high strength glass-fiber epoxy. The outside diameter of the tube 33 is slightly smaller than the bore 20c and the wad sections and may be the same as the outside diameter of nozzle element 30, as shown clearly in FIGURE 5. Referring again to FIGURES l and 2, the forward end of casing 21 is securely clinched or formed at 34 to retain the tube 33 snugly assembled to the casing before firing. At this time, the elements 26, 27 and 30 are all in contacting relation.

The interior of the tube 33 for a major portion of its length contains a charge of propellant grain 35 or appropriate solid ty-pe fuel. Centrally of the propellant mass, there may be arranged an igniter core 36 of magnesium or like highly combustible material, the rear end of which projects into the ignition chamber 37 of nozzle element 30. In some instances, the element 36 may be dispensed with.

Forwardly of the propellant charge, a closure plug 38 is mounted within the tube 33 and forms the rear wall of a shot or payload cavity 39 having a front crimp closure 40 which opens at the proper time to release the shot charge 41 close to the target. In this connection, forward inertia of the shot charge will open the crimp closure 40 to discharge the payload in a compact pattern near the target when the rocket fuel is spent and air drag is slowing down the projectile. In some cases, the shot charge may be retained in the tube 36 after burn out of the propellant charge and ejected later by a small powder charge, not shown, ahead of the plug 38. Additionally, in lieu of the pellet shot charge, a single projectile of the bullet or ball type may be employed in the payload cavity in some cases.

Forwardly of the rocket nozzle opening 31 there is provided in the block or element 30 a plurality of circumferentially equidistantly spaced nozzle openings 42, FIG- URE 3, for the purpose of producing spinning of the projectile to stabilize the same in liight and control the shot pattern and dispersion. As shown, the spin nozzles are flared as they open through the periphery of the element 30 and their inner reduced diameter portions 43 are tangent to the surface of the chamber 37. The number and size of the spin nozzles may lbe varied somewhat in the invention as found desirable. Additionally, the .projectile may be stabilized in flight by other means such as stabilizing fins which open up automatically when the tube 33 emerges from the gun barrel. The feature of the spinproducing nozzles is another optional feature although a very advantageous feature of the invention.

Referring briefly to 'FIGURE 9 of the drawings showing a modification, additional optional forward spin nozzles 44 may be provided in the tube 33 and within a modied plug 33 immediately rearwardly of the payload cavity 39. These forward spin nozzles may be advantageous because their location is near the center of gravity of the projectile.

FIGURE 4 shows the condition of the round immediately after firing and while still within the barrel 20. The primer 23 has been fired and the gun boost powder charge 25 has exploded. Gun boost gases 21 within the casing 21 rearwardly of wad section 26 are now exerting high pressure and thrust upon the wad section and this gun boost pressure may range from about 4000 to 12,000 p.s.i. Consequently, the Wad section 26 and all parts of the round ahead of it are thrust substantially instantly from the casing 21 as depicted in FIGURE 4. However, to limit pressure, gun recoil and shot acceleration and deformation, the gun boost pressure and velocity is controlled so as to be materially less than in a conventional shotgun. The rst increment or stage of velocity imparted to the round is thus developed solely by this gun boost pressure in generally the sarne manner as in a shotgun althoughcontrolled and limited as stated.

Almost simultaneously the gun boost gases 21' will flash through igniter bores 28 and 29 and nozzle opening 4 31 to ignite the core 36 or fuse and this will immediately initiate burning of the propellant charge 35, as shown. The propellant charge will decay or burn from the inside out after ignition as best shown in FIGURE 5. At this time, the pressurized gases in the chamber 37 will begin to flow tangentially from the spin nozzles 42 and the round will begin to spin Slowly while still in the gun barrel. As soon as the propellant 35 begins to burn appreciably, the main nozzle 31 Will begin expelling gases rearwardly and the round will `begin to Vbe propelled by rocket motor action. However, the wad 26-27 seals the nozzle opening 31 substantially until sufficient operating pressure for thrust is developed by the rocket motor, and this condition will not prevail until the round exits the muzzle.

Referring to FIGURE 5, where the round or projectile has cleared the barrel 20, the gun boost effect has ended and the round is self-propelled toward the target solely by its rocket motor as the propellant 35 continues to burn. It is at this time that a large second velocity increase develops beyond the muzzle of the gun due to rocket motor action. Also, spinning of the round continues under inliuence of the spin nozzles 42 where these are employed. To successfully counteract rocket thrust misalignment, the rate of spin need not be great and may be as little as 5-25 revolutions during the burning cycle of the propellant 35. This rate of spin will be sufficient to maintain a high degree of accuracy for the round in ight.

Referring to FIGURE 6, when the propellant charge is burned out or spent substantially and rocket motor action ceases, the tube 33 will decelerate very quickly and the inertia force on the shot charge 41 will cause it to eject through the crimp closure 40 and strike the target with maximum energy and while still in a tight pattern with little spread. As previously mentioned, in some cases, the shot charge may be retained after rocket burn out and ejected later 4by an auxiliary powder charge ahead of the plug 38. Suitable fusing may be employed to explode this additional charge. |In any event, the range, accuracy and velocity of the payload greatly exceeds that of conventional Shotguns, with the added advantages of lightweight gun construction, lower recoil, lessened muzzle blast, and overall increased safety. l

The ammunition round has additional features including the following. The internal pressure which the tube or body 33 can withstand is about 100-3000 p.s.i. Since the initial gun boost pressure caused by exploding the powder charge 25 greatly exceeds these limits, some means is necessary to prevent overpressurizing of the rocket body or tube. To accomplish this, the restricted igniter bore 28 tends to control pressurizing of the chamber 37 and the region of the rocket ybody ahead of it and thus acts as a restriction on the gun boost pressure while allowing suificient passage of the exploding gases to ignite the rocket fuel. Also, immediately after separating from the casing 21, the spin nozzles 42 `become exposed in the barrel bore and are able to vent or bypass sorne of the gun boost gases to further guard against over-pressurizing of the tube 33. In addition to this important pressure-relieving function and the igniting of the rocket fuel, the wad structure also helps to cushion the shock caused by explosion of the charge 25, since some of the gun boost gases may enter the bore 28, as explained. The obturating or sealing of gun boost gases by the wad section 26 is such that maximum consistent pressure and velocity are obtained during the gun `boost phase.

It might be mentioned additionally that the spin nozzles 42 may Ibe angled to impart some forward thrust to the round as well as rotation. The spin nozzles, if used, are always forwardly of the wad structure which separates the gun boost gases substantially from the rocket motor during gun boost acceleration in the barrel. The spin nozzles may be designed to induce a more rapid spin to the projectile =for stabilizing it gyroscopically in some cases.

FIGURE 7 shows a modication to facilitate the spinning action of the round during gun boost or while still in the barrel 20, although separated from the casing 21. In FIGURE 7, one or more apertured discs 45 having central openings 46 are provided between the nozzle ele ment 30 and wad sections 27. These discs are made of a low friction material, such as Teflon, or may be coated with a low friction compound. The rear face of nozzle element 30 may be similarly coated to reduce friction. The openings 46 are in registry with the main rocket nozzle opening 31 and the bores 29 and 28 to facilitate ignition of the rocket in the manner described. The discs 45 greatly encourage the development of spin during the early gun boost phase. This is an optional feature of the invention which need not ybe employed. All other parts remain the same as previously described.

FIGURE 8 shows a further slight modification wherein the main thrust nozzle opening 31 is tapered or flared for increased thrust efficiency. In conjunction with this, there is introduced into the wad structure a third thin section 47 having a tapered nose 48 intertting with the nozzle opening 31 to initially substantially close the same. The wad section 47 has a restricted bore 49 to admit hot gases for ignition of the rocket as described. All other parts remain the same as previously described.

FIGURES through 12 of the drawings show several possible formations of another feature which may be ernployed, namely the provision of a choke section in the forward portion of the round. The purpose of the choke section is to allow regulation of the shot pattern and velocity within certain limits. Referring to FIGURE 10, the rocket tube or body 33 has a forward stepped bore portion indicated at 50 ahead of the shot charge 41 in cavity 39. A suitable closure disc 51 separates the stepped choke section or bore portion of the round from the cavity 39', and the forward end of the round has a crimp closure 40'. A portion of the propellant charge 35 is shown in FIGURE 10 communicating with flash openings 53 leading to a powder charge 54 immediately ahead of wall portiton 38. Wadding 55 separates the shot charge 41 from the powder 54, as shown. The remaining parts of the projectile or round remain unchanged. The stepped choke section 50 enables the powder charge 54 to impart an increased increment of velocity to the shot as it is expelled. When the powder charge 54 is ignited, the wadding 55 and the shot charge 41 are thrust forwardly into the stepped choke section and the crimp closure `40 opens. The stepped wall 50 provides for a controlled spreading of the shot because of a controlled velocity increment perpendicular to the longitudinal axis of the charge being expelled.

FIGURE 1l shows another version of choke section on the frontal section of the round having a forwardly flared bore 56 of gradually increasing diameter instead of the stepped bore 50. In other respects, the construction may be identical to FIGURE l0 and the purpose and function of the choke section in the round is basically the same, namely, to regulate the shot pattern and velocity.

FIGURE 12 shows still another version of the choke section wherein the choke bore portion 57 is tapered but converges forwardly producing a velocity increment effecting the shot charge perpendicular to the longitudinal axis of the charge or round tending to control shot dispersion. All other structural features may be identical to the previous embodiments. As previously suggested, the spinning of the round in flight may also aid in controlling pellet dispersion. It is desired to reemphasize another important feature of the invention, namely, that the accelerations and resultant forces to which the round is subjected are low compared to the ordinary shotgun and this reduces or eliminates flattening or deformation of shot pellets within the body of the shot charge, again resulting in better shot charge patterns. The several advantages of the invention over conventional rounds should be readily apparent to those skilled in the art without further discus* sion herein.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferred examples of the same, and that various changes in the shape, size and arrangement of parts may be restorted to, without departing from the spirit of the invention or scope of the subjoined claims.

I claim:

1. An ammunition round which receives a first stage of acceleration while within a gun barrel and a second stage of acceleration outside of the barrel, said round comprising a casing adapted for mounting in a gun chamber and having a firing primer, an explosive gun boost powder charge within the casing to effect said rst stage of acceleration upon exploding by creating high pressure gases, a plural section obturating wad in the casing immediately ahead of said gun boost powder charge and said wad having a Central axial ignition passage formed entirely through all sections thereof, a projectile body forwardly of said wad and having a portion of the body secured within the casing prior to firing the round, said projectile body containing a propellant charge supplying said second stage of acceleration outside of the barrel, a rocket nozzle element on the rear end of said projectile body having a rear central axial nozzle opening registering directly with said ignition passage and said nozzle element directly with said ignition passage and said nozzle element directly abutting the forwardmost section of the wad, a shot pellet projectile payload on the projectile body forwardly of the propellant charge, and the projectile body having a forward end crimp closure for said payload.

2. An ammunition round as delined by claim 1, and wherein said nozzle element has plural circumferentially spaced tangential spin nozzle openings formed therein in communication with said enlarged ignition chamber.

3. An ammunition round as defined by claim 1, and said nozzle element having an enlarged ignition chamber therein immediately forwardly of said nozzle opening and the forward end of said chamber spanning the major cross sectional area of said propellant charge in the projectile body, an igniter core embedded centrally in said propellant charge and having a rear end portion projecting into said ignition chamber centrally.

References Cited UNITED STATES PATENTS 2,421,752 6/ 1947 Jones 102-38 2,426,239 8/ 1947 Renner 10238 2,884,859 4/ 1959 Alexander et al 102-38 2,986,998 6/1961 Clark 102-95 X 3,093,073 6/1963 Lockwood et al 102-95 X 3,097,169 7/1963 Hall 102-95 X 3,233,546 2/1966 Foote et al.

3,234,877 2/1966 Herter 102-95 3,313,235 4/ 1967 Middleton.

3,326,128 6/1967 Choate 102*38 ROBERT F. STAHL, Primary Examiner U.S. C1. X.R.

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