Abstract:
Non-lethal ammunition for a riot gun assembles a bi-chambered projectile body and an impact nose, the assembly being spin-stabilized and nose-heavy such that the nose will impact first at the target. The rearward end of the assembly is mounted into the forward end of a shell casing having a high-energy gas expansion chamber, the mounting forming a low-pressure chamber at the rearward end of the projectile. A cup-shaped multi-port gas diffuser plug, spaced from the projectile body, directs burnt propellant gases from the expansion chamber into the low-pressure chamber to expel the projectile at a relatively low velocity. A sleeve interiorly of the gas diffuser plug closes the ports and is degraded by the burnt gases to provide a complete burning of the propellant.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a completion application of and claims the benefit of U.S. Provisional Application No. 60/903,436, filed Feb. 26, 2007, the entire disclosure of which is incorporated herein in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to the field of non-lethal/less lethal ammunition wherein a projectile, such as used in riot control, is fired from the barrel of a held grenade launcher and, respectively, shatters to release a dye or gas and/or remains intact upon impact, respectively, to produce trauma. More specifically, the invention relates to such ammunition having a high/low gas propulsion system wherein high-energy propellant gases are created in a small high pressure chamber, efficiently burned, and the high pressure instantaneously released into a larger volume to expel the projectile from a cartridge and the barrel of a gun at a controlled relatively low exit velocity, and a projectile having a configuration such that the nose thereof will hit a specifically identified target upon impact. 
         [0004]    2. Description of the Prior Art 
         [0005]    Non-lethal or less lethal ammunition provides friendly forces with the capability to stop, confuse, disorient, or momentarily deter a potential threat without using deadly force. Military forces and local police units use non-lethal ammunition to apply the minimum force necessary while performing functions of crowd control and site area security. In particular, the non-lethal/less lethal ammunition is intended to be a direct fire, low hazard, non-shrapnel producing device that statistically will produce less lethal trauma upon impact and a low probability of death upon impact. 
         [0006]    Typically, the less-lethal ammunition includes a large caliber metallic cartridge case that fits into the chamber of the launcher, a smooth or rifled barrel, a projectile, a smaller caliber propelling charge, such as a .38 or .44 that houses a percussion cap, and a propellant to expel the projectile. The large caliber cartridge case is in the form of a cylindrical shell casing with the forward end portion receiving the projectile and the rearward end portion receiving the smaller caliber cartridge propelling charge case inclusive of propellant and percussion cap. In use, the cap is struck by a firing pin, the propellant ignited, and the efficient burning of the propellant in a confined area generates a pressurized gas that instantaneously releases its pressure into the larger cartridge case and forces the projectile out of the forward end portion of the large caliber cartridge casing and then, typically, through the bore of a smooth or rifled barrel. 
         [0007]    The propellant is oftentimes in the form of gunpowder that fills the small caliber shell casing of a conventional pistol cartridge, such as a commercially available .38 or .44 caliber cartridge. The powder in the shell when ignited provides a high energy burst of gas that expels the projectile from the large caliber cartridge and at a high velocity. The hi-lo system, as described in the previous paragraph differs in operational concept to the system described herein. Riot control ammunition and less lethal ammunition is considered to be non-lethal or less lethal if the projectile velocity is low and usually lethal if the projectile velocity is high. 
         [0008]    U.S. Pat. No. 5,086,703 (issued Feb. 11, 1992) to Klein discloses a non-lethal riot control cartridge wherein the intention is to accelerate a relatively large mass (relative to the amount of propellant involved) to a relatively low velocity, which patent is specifically incorporated herein by reference. 
         [0009]    In Klein, a large caliber such as a 37 mm or 40 mm metal cartridge contains and seats a small propelling charge such as a .38 or .44 caliber inside a chamber formed at the rearward end of a bi-chambered projectile. When the percussion cap in the cartridge is fired, high-pressure propellant gases fill the projectile chamber and force the projectile forwardly with respect to the cartridge. Upon reaching and moving forward of the propelling charge, the high pressure gas is released into the larger volume of the 37 mm or 40 mm cartridge case, forcing the projectile through the barrel of a grenade-launching weapon. The result is the creation of a high-pressure chamber within the metallic cartridge and the base of the projectile and a low-pressure chamber within the larger 37 mm or 40 mm cartridge case located in the space behind the projectile as the projectile moves forward, clearing the expulsion end of the .38 or .44 cartridge case to exit the weapon. Such a system is often referred to as a “Hi/Low” gas delivery system. 
         [0010]    Depending on the application, discharge velocity, or to control trajectory and distance, the bore of the gun barrel or tube may be rifled or smooth. The rifling provides spin-control and promotes dynamic stability to ensure that that nose of the projectile will impact at a selected target. Further, careful consideration of projectile geometry, payload and the like may also contribute to ensuring that a target aimed at will be reached and the payload expelled. 
         [0011]    U.S. Pat. No. 7,086,337 (issued Aug. 8, 2006) to Klein discloses non-lethal ammunition for a riot gun which includes a forwardly open casing, a projectile mountable in and dischargeable from the casing, a propellant cartridge extending into the casing interior, and a UV curable adhesive disposed in sealing relation about the propellant to effectuate uniform firing of the projectile. The projectile includes rearward and forward end portions each provided with a central cavity with the rearward cavity enclosing the cartridge, a weight in the forward cavity for balancing and increasing the mass of the projectile, and a subassembly carrying in a nose thereof a chemical payload or chemical agent, the subassembly including a stem sized for interference fitment within the forward cavity to secure the subassembly to the projectile and having a chamber for positioning the weight in the forward cavity 
         [0012]    Although many of the known riot control systems are believed suitable for the uses intended, there is an ongoing need for improvements in such ordnance. 
         [0013]    An object of this invention is the provision of high-low pressure non-lethal/less lethal ammunition that uses the high pressure provided by ignition of a conventional explosive, such as from firing a standard .38 or .44 cartridge case, to create a high-pressure gas to provide a predictable and reliable quantity of low-pressure gas to propel a projectile, fitted to the cartridge, away from its fitment at a relatively low but predetermined velocity. 
         [0014]    Another object of this invention is the provision of non-lethal/less lethal ammunition having a gas delivery system that will effectively control and transform the high-energy burst of the propellant from a high velocity to a low velocity. 
         [0015]    Another object of this invention is provision of a gas delivery system in non-lethal/less lethal ammunition that will direct and diffuse the energy of propellant gases from a high-pressure expansion chamber into a low-pressure chamber to propel the projectile from the cartridge and weapon at a low velocity. 
         [0016]    Another object of this invention is provision of non-lethal/less lethal ammunition having a removable and reloadable high-pressure chamber. 
         [0017]    Another object of this invention is provision of non-lethal/less lethal ammunition having a reloadable cartridge system, including a reloadable delay sleeve that controls the burning and replaced for the next use of the cartridge, that is cost effective and saves costs in training. 
         [0018]    Another object of this invention is provision of non-lethal/less-lethal ammunition having a reloadable propelling charge that consists of a modified conventional .38 or .44 cartridge case, primer and propellant which is the power source for firing and replaced for the next use of the cartridge, that is cost effective and saves costs in training. 
         [0019]    Another object of this invention is provision of non-lethal/less lethal ammunition having a projectile that is configured to fly, and impact, nose first, while describing a predetermined ballistic trajectory. 
         [0020]    Another object of this invention is provision of non-lethal/less lethal ammunition wherein the balance and/or weight of the projectile may be changed simply such as by varying the thickness of the walls or base and/or making the walls or base thinner or thicker. 
         [0021]    Another object of this invention is the provision of a spin-stabilized projectile that does not shatter upon impact, and carries an aerodynamic shaped nose (or payload) comprised of a material that does not shatter upon impact, but bounces or expands, or a material having a payload chamber for carrying a tear gas and other non-lethal chemicals that shatters and the chemicals dispersed upon impact. 
         [0022]    Another object of this invention is the provision of a projectile configured such that the mass center, or center of gravity, of the projectile is located proximate the nose at the forward end of the projectile so as to maintain the nose in position for impact. 
         [0023]    Another object of this invention is the provision of spin-stabilized combination of grenade launching tube and expellable projectile, the projectile being generally cylindrical, bi-chambered, and provided with an exterior driving band, or obturating rib, in encircling relation with an interior bulkhead that divides the projectile into two interior chambers, the driving band cooperating with the interior wall of the launching tube to control spin of the projectile when propelled therefrom. 
         [0024]    It would be desirable, and is an object of this invention, to provide non-lethal riot gun ammunition that has the desired accuracy and which employs a projectile which is usable for different types of applications (i.e. a barricade penetrating tear gas head, UV, dust dispersal, trauma inducing etc.), thus improving upon manufacturing techniques and reducing costs. 
         [0025]    As subsequently detailed, the present invention is directed to and achieves the above desired objects. 
       SUMMARY OF THE INVENTION 
       [0026]    The instant invention provides a non-lethal/less lethal ammunition comprising: a bi-chambered projectile and a cup-shaped shell casing, the projectile being releasably mounted at a rearward end to the casing and closed at a forward end by a nose, and configured such that the center of gravity of the assembly (projectile and nose) is towards the forward end of the assembly whereby the nose will impact upon reaching a target, the casing including a gas supply arrangement wherein a gas diffuser plug consisting of a removable and reloadable high pressure chamber and a degradable delay sleeve are arranged to radially discharge uniformly burnt propellant gases at high energy and reduce the gases to a lower pressure, wherein degradation of the delay sleeve materials controls the rate of discharge and ensures that complete uniform burning takes place, and wherein the low pressure gases engage a cup-shaped chamber at the rearward end of the projectile body wherein to propel the projectile assembly from the casing at a low velocity. 
         [0027]    The invention provides non-lethal/less lethal ammunition for use in a riot control firearms such as 37 mm and 40 mm firearms/launchers. 
         [0028]    The invention provides non-lethal/less lethal ammunition wherein a projectile body permits a desired payload to be loaded for a desired circumstance by merely choosing the correct nose configuration. 
         [0029]    According to this invention, in a first preferred embodiment thereof, non-lethal/less lethal ammunition for the controlled delivery of a projectile to a target, comprises: 
         [0030]    a cup-shaped casing, said casing including a high-pressure expansion chamber to receive an explosive propellant; 
         [0031]    a cylindrical projectile, said projectile being expellably mounted in said casing and comprised of a non-rupturable material adapted to remain intact and not burst into pieces following a violent impact, said projectile including, respectively, rearward and forward end portions, said rearward end portion and said casing cooperating to form a low pressure chamber when the projectile is mounted to the casing; 
         [0032]    an impact nose secured to the forward end portion of said projectile; and 
         [0033]    a gas diffuser system for receiving high energy propellant gases from the expansion chamber and delivering the high pressure of the same into the low pressure chamber formed by the 37 mm/40 mm cartridge case following substantially complete and uniform burning of the propellant, said diffuser system being axially spaced from said projectile. 
         [0034]    According to this preferred embodiment, the removable and reloadable high-pressure gas diffuser system comprises: 
         [0035]    a gas diffuser plug, said plug including a cup-shaped body having a hollow interior, and a replaceable delay sleeve of degradable material, said cup-shaped body including a sidewall having an interior surface, a closed upper end, an open lower end, and at least one gas outlet port in said sidewall, and said delay sleeve being disposed in said hollow interior and in facing and closing relation, respectively, with and against said interior surface and said gas outlet port; and 
         [0036]    means for connecting the gas diffuser plug to said casing, said means for connecting placing the expansion chamber in fluid communication with the hollow interior of said gas diffuser plug and orienting the outlet port for directing propellant gases in a direction transverse to the expelling direction; 
         [0037]    wherein uniformly burnt high energy propellant gas from the expansion chamber is first directed in a first direction generally along the geometric axis of the projectile and said casing, then in a second direction generally transverse to the geometric axis by degrading the material of the delay sleeve to pass through the outlet port or ports and into the low pressure chamber, and then in the first direction to be received in the first chamber and expel the projectile from the casing. 
         [0038]    The sidewall of the gas diffuser plug is generally cylindrical. To adequately distribute the gases, the plug sidewall preferably includes a plurality of gas outlet ports. In one application, the gas diffuser plug includes four gas outlet ports arranged generally equiangularly about the sidewall and adapted to direct the burnt gases radially relative to the geometrical axis of the gas diffuser plug. 
         [0039]    The replaceable delay sleeve is preferably comprised of a suitable material that will degrade, over time, when exposed to the high pressure and temperature of burnt propellant gases, to control and enable complete and uniform burning of the propellant. 
         [0040]    The rearward end of the projectile body forms a cup-shaped chamber that is generally symmetrically centered along the geometric axis of the projectile, and formed by a generally cylindrical or annular surface, and a continuous planar surface that is transverse to the axis of the projectile. The burnt propellant gases from the diffuser plug are delivered into the low-pressure chamber and generally uniformly distributed across the planar surface to expel the projectile outwardly of the casing at a predetermined relatively low velocity. 
         [0041]    The center of mass of the assembly of the projectile body, payload, and nose is proximate the forward end of the projectile assembly, wherein the projectile assembly will fly oriented with the impact nose first while describing a ballistic trajectory. 
         [0042]    The nose is removably fitted into the forward end portion of the projectile body, thus enabling differently configured noses and payloads carried thereby to be replaced in a projectile body and expelling casing 
         [0043]    Preferably, the nose is comprised of non-rupturable and rupturable materials or component parts. In one application, the nose is comprised of non-rupturable elastomeric material, and is a “bouncer”, and the projectile body is comprised of a polymeric material that does not shatter or break apart upon impact, such as nylon. In other applications, the nose carries a chemical to be dispersed and shatters upon impact. 
         [0044]    Further, in some applications, the delay sleeve may be comprised of a thin metallic or plastic sleeve, which sleeve will degrade when the sleeve interacts with the burnt high energy propellant gases. 
         [0045]    In another preferred embodiment, there is provided according to this invention non-lethal/less lethal ammunition adapted to launch a projectile from a tube, comprising: 
         [0046]    a cup-shaped shell casing having a primer end and a payload expelling end, said primer end including a high energy expansion chamber for burning propellant gases and a cup-shaped gas diffuser plug for the controlled delivery of said burnt gases, said gas diffuser plug including an interior cavity for receiving burnt gases from said expansion chamber, at least one outlet port for radially discharging burnt propellant gases from said interior cavity, and a replaceable delay sleeve of degradable material, said delay sleeve being disposed in closing relation with said outlet port and of a material adapted to substantially simultaneously permit the propellant to burn completely and the sleeve material to degrade whereby to expose the outlet port and permit burnt propellant gases to pass through the outlet port; 
         [0047]    a generally cylindrical bi-chambered projectile body of non-rupturable material expellably mounted in the expelling end of said shell casing, said projectile body including a rearward end portion mounted to the expelling end and in spaced relation to the gas diffuser plug, a forward end portion remote to the casing, a bulkhead dividing the interior of the projectile body into first and second chambers, and an exterior driving band to cooperate with the interior wall of the launching tube to spin-stabilize the projectile when launched, said first chamber being disposed in said rearward end portion, shallow, generally cup-shaped, and in juxtaposed spaced relation to said gas diffuser plug to form, with said casing, a low pressure chamber for receiving and distributing burnt propellant gases across the bulkhead, and said second chamber being disposed in said forward end portion; 
         [0048]    a nose removably mounted in said second chamber; 
         [0049]    wherein an assembly of said projectile body and said nose has a center of mass proximate to the forward end of the projectile body to enable the projectile to fly and impact nose first while describing a desired ballistic trajectory. 
         [0050]    The nose may be solid and of non-rupturable material. Further, the nose may be multipart, include an interior chamber for carrying a payload, and be comprised of a rupturable material that breaks apart to disperse the payload upon impact. The nose includes a body portion dimensioned for fitment into the second chamber and in closing relation therewith, a forward impact head, and a payload for carrying teargas and the like, and which will deploy or otherwise scatter upon impact. 
         [0051]    The non-lethal/less-lethal ammunition further comprises a gunpowder charge in the expansion chamber, and a percussion cap for exploding said gunpowder charge. 
         [0052]    According to an aspect of this invention, there is provided a cartridge for the controlled delivery of a fluid comprising: 
         [0053]    a cup-shaped shell casing, having a closed lower end, an open upper end, and a continuous vertical cylindrical side wall thereby defining a hollow interior; 
         [0054]    a high energy expansion chamber provided in said lower end; 
         [0055]    an explosive propellant charge in said expansion chamber; 
         [0056]    a percussion cap in operable relation with said charge to explode the propellant; and 
         [0057]    a cup-shaped gas diffuser plug, having an open lower end, a closed upper end, and a continuous vertical cylindrical wall thereby defining a hollow interior cavity, the upper end portion of said cylindrical wall including a plurality of generally equiangularly spaced outlet ports for passing burnt gases radially from the interior cavity to the hollow interior, and a replaceable delay sleeve of degradable material disposed in said interior cavity and in closing relation with the outlet ports, communication of burnt gases into said interior cavity causing the material of the sleeve to degrade, over time, and be removed from closing relation with the outlet ports. 
         [0058]    According to this invention, a brass or aluminum .38 or .44 caliber cartridge insert, which holds the propellant and primer, is pressed into a bore formed in the base of the shell casing. 
         [0059]    The launching weapon firing pin strikes the primer igniting the propellant or gun powder inside the propelling charge. The burning propelling charge located partially inside the gas diffuser plug lined with the delay sleeve generates sufficient pressure and heat to burn through the delay sleeve to release the expanding propellant gases through the outlet port and into the low-pressure chamber. The rotating driving or obturating band around the projectile body engages rifling in the launcher tube and imparts a spin to the projectile. The pressure, created by the expanding gases in the low-pressure chamber, forces the projectile through the launching tube. 
         [0060]    In a typical example, the spin imparted to the assembly of the projectile and impact nose is in the order of 2,000 plus rpm, and the discharge velocity of about 237 feet per second. Upon impact, depending on the nose, the nose bounces, expands, or shatters, causing the chemical payload to disperse, to incapacitate without causing a fatality. In no condition does the projectile casing ever shatter or rupture, such as by the nose impact forces being transmitted thereto. 
         [0061]    The delay sleeve, propelling charge, and the nose are changeable to accommodate the type of ammunition desired. 
         [0062]    The various features, advantages and other uses of the present invention will become more apparent by referring to the following description and drawings. 
         [0063]    Throughout the following description and drawing, identical reference numbers refer to the same component shown in multiple figures of the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0064]      FIG. 1  is an exploded assembly view, in perspective, of non-lethal/less lethal ammunition according to the present invention, with a large caliber casing of a projectile mounting cartridge thereof partially cut-away to show detail; 
           [0065]      FIG. 2  is a cross-sectional view of the non-lethal ammunition, when assembled and mounted in the bore of a firing tube (shown in phantom), according to the present invention; 
           [0066]      FIG. 3  is a side elevation view, in section, showing detail of a removable and replaceable gas diffuser plug operably associated with the mounting cartridge for communicating burnt high energy propellant gases used to propel a projectile of the ammunition of the present invention; and 
           [0067]      FIG. 4  is a side elevation view, in section, of the rearward end of the non-lethal ammunition illustrating a gas delivery system wherein burnt high-energy propellant gases are directed radially outwardly and upwardly from the gas diffuser plug and then upwardly and into a low-pressure chamber formed in the rearward end of the projectile body wherein to propel the projectile from the firing tube/launcher barrel. 
           [0068]      FIG. 5  is a cross-sectional view of an alternate embodiment of non-lethal ammunition according to the present invention 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0069]    Referring now to the drawings, and in particular to  FIGS. 1 and 5 , preferred embodiments of non-lethal projectile ammunition according to the present invention are shown. Each is similar but differs in the payload utilized. In the ammunition shown in  FIG. 1 , the nose of the ammunition is solid, whereas in  FIG. 5 , the nose carries a payload, such as tear gas, as will be described in greater detail herein below. As will be described, each projectile ammunition is of the non-lethal or less lethal type and includes a removable and replaceable high-low propulsion system wherein high-pressure propellant gases in a pressure expansion chamber of the casing is diffused and delivered to a low-pressure chamber formed between the rearward end of the projectile body when expellably mounted to the casing. 
         [0070]    The ammunition maintains strict compliance with the caliber or size requirement of the weapon or firearm (not shown) used to fire the ammunition. Illustrative of an application using the non-lethal ammunition herein is the M203 breech loading grenade launcher with rifled barrel that attaches to the M16 assault rifle or the M4 carbine and designed for a single shot 40 mm grenade. Typically, the M203 launches grenade ammunition through a 40 mm bore with a muzzle velocity of about 250 feet per second (76 m/s), to have an effective range as needed, depending on the application. In some applications, a smooth barreled weapon may be used. 
         [0071]    Referring to  FIGS. 1 and 2 , the non-lethal ammunition according to this invention is generally denoted by the reference number  10 . The projectile ammunition  10  includes a shell casing  12 , a projectile body  14 , and an impact nose  16 . The nose  16  is solid, not designed to rupture, formed into one-piece, of non-rupturable material or comprised of non-rupturable components, and comprises the payload. 
         [0072]    The casing  12  is of a suitable metal, such as aluminum or the like, generally cup-shaped and includes a cylindrical sidewall  20  closed at a lower end by an end wall  22  and forms an interior chamber  24  leading to a payload expelling opening  26  (see  FIG. 1 ) at the forward end. The end wall  22  includes an exterior end face  28  and a cylindrical bore  30  extends between the end face  28  and interior chamber  24 . A cartridge case insert  32 , which holds a propellant, such as gunpowder, and includes a primer or percussion cap, is pressed into the bore. Preferably, the propelling charge is loaded with smokeless gunpowder. The bore  30  forms a high-pressure expansion chamber to contain burnt propellant gases of the insert when the percussion cap is struck by the weapon pin. 
         [0073]    Typically, the casing  12  is a readily available 40 mm cartridge case of aluminum. 
         [0074]    The projectile  14  is in the form of a generally cylindrical shell or body  34  having rearward and forward end portions  34   a  and  34   b  and an interior wall or bulkhead  36  which divides the interior of the projectile body  34  to form rearward and forward chambers  38  and  40 , respectively, in the rearward and forward end portions  34   a  and  34   b . The rearward chamber  38  is generally cup-shaped and includes a cylindrical or annular wall  38   a  and a flat generally planar circular wall  38   b . The rearward facing surface  38   b  of the bulkhead  36  is disposed in a plane generally perpendicular to a geometrical axis “A” passing through the projectile body  34  and shell casing  12  when the projectile  14  is expellably assembled to the casing  12 . The rearward chamber  38  of the projectile in combination with the interior chamber  24  of the shell casing  12  forms a low-pressure chamber into which the high-energy expansion gases are directed. The expansion gases distribute generally uniformly across the flat surface  38   b  to promote controlled expulsion. 
         [0075]    The forward chamber  40  is elongated, generally cylindrical, longitudinally extending, and outwardly open to receive the impact nose  16 . 
         [0076]    An obturating or driving band  42 , generally at the location of the bulkhead  36 , extends around the exterior of the projectile body  34  and is dimensioned to form a snug closure with the interior wall “W” (see  FIG. 1 ) of the launch tube “T” to assist in spin-control. 
         [0077]    A pair of grooves  44  and associated ribs  46  are formed around the exterior of the rearward end portion  34   a  to assist in controlled retention in the shell casing  12  and control spin during expulsion of the projectile body  34  from the casing  12 . Additionally, the grooves  44  and ribs  46  cooperate in preventing, or at least reduce the energy of, burnt high-energy propellant gases passing between the fitment interface formed by the projectile body  34  and the sidewall  20  of the shell casing  12 . In this regard, one or both of the grooves are fitted with an O-ring seal  41 . 
         [0078]    Preferably and according to this invention, the projectile body  34  is comprised of a material that is resistant to rupture or shattering. It is important that the material of the projectile body does not suddenly break or burst into pieces upon application of a violent impact or blow thereto, such as resulting from impact of the nose  16  against a destination target. 
         [0079]    According to this invention, a suitable material is an acetyl homopolymer, such as Delrin®. These polymers have high tensile strength, impact resistance and stiffness, outstanding fatigue endurance, and resistance to many chemicals. Further, these polymers offer dimensional stability and maintain natural lubricity at a wide end-use temperature range. 
         [0080]    The nose  16  is generally cylindrical and includes a shaped head  48 , and a body member  50 , each arranged on a common axis, which axis is aligned with the geometric axis “A” when the nose  16  is assembled to the forward end portion of the projectile body  34 . The shaped head  48  includes a cylindrical exterior surface  48   a , a flat end face  48   b  adapted to face forwardly, and a flat end face  48   c  adapted to face rearwardly and seat against the forward end  34   d  of the projectile body  34 . A rounded transition surface connects the exterior surface  48   a  to the end face  48   b  to improve the flight ballistics when the projectile moves through the air. 
         [0081]    The body member  50  extends coaxially rearwardly from the end face  48   c  of the head  48  and includes a cylindrical exterior surface  50   a  and an end face  50   b . The exterior surface  50   a  and end face  50   b , at least in part, define a series of locking tabs which act against the surface  34   c  of the projectile body  34  and provide a snug gripping engagement therewith to permit the impact nose  16  to be removably mounted to the projectile  14  and form an end closure to the forward chamber  40 . 
         [0082]    The nose  16  is designed not to rupture. The nose  16  is formed into a one-piece component and from a material selected that is not rupturable. While many materials are contemplated, preferably the nose is comprised of nylon, a polyurethane elastomer, or a combination of both. 
         [0083]    In another embodiment according to this invention, as shown in  FIG. 5  and discussed hereinbelow, a like-shaped nose  116  is comprised of a rupturable material, or components that enable the nose  116  to rupture. 
         [0084]    According to an important feature of this invention, a gas delivery or diffuser system is provided wherein a gas diffuser plug  54  is placed in fluid communication with the expansion chamber  30  to receive burnt high-energy propellant gas from the expansion chamber  30 , reduce the pressure, and direct the burnt propellant gases into a low-pressure chamber, formed by the combined chambers  24  and  38  formed behind the rearward end of the projectile body  34 , when the projectile  14  is expellably mounted to the shell casing  12 . 
         [0085]    As shown in  FIG. 3 , the gas diffuser plug  54  is generally cup-shaped having a cylindrical sidewall  54   a  and a flat closure head  54   b , and forms an interior cavity  54   c  adapted to receive the burnt high-energy propellant gases. 
         [0086]    While many materials are suitable, preferably the gas diffuser plug  54  is of a metal that resists degradation by burnt gases, such as steel or stainless steel. Preferably, the shell casing  12  is of brass or aluminum. 
         [0087]    At least one vent hole or gas outlet port  54   d  is provided in the sidewall  54   a  to pass the burnt propellant gases from the bore  30  into the casing interior  24 . Preferably, a plurality of gas outlet ports of suitable diameter and shape are provided to ensure uniform distribution of burnt propellant gases. In the embodiment illustrated, four outlet ports  54   d  are provided, each generally circular in shape, disposed equiangularly, and adapted to pass the burnt gases radially (i.e., in a direction transverse to the expelling direction). 
         [0088]    Matching thread  60  is provided on the exterior sidewall  54   a  of the plug  54  and on the interior wall of the bore  30  to enable the gas diffuser plug to be removably mounted to the shell casing  12 . To enable rapid replacement or permit cleaning and recharging of the shell casing for reuse, the top surface of the closure head  54   b  is provided with a slot  54   e  adapted to be engaged by a conventional tool, such as a screwdriver. 
         [0089]    Further, and important to the invention herein, a replaceable delay sleeve  56  of degradable material is fitted into the high pressure interior cavity or chamber  54   c , against the interior surface  54   f  of the sidewall  54   a , and in closing relation with the vent hole or outlet port  54   d . The delay sleeve  56  is of material adapted to degrade by the action of the burnt high-energy propellant gases directed thereagainst and of a thickness calculated such that the propellant in the shell casing  12  will completely burn substantially simultaneously with the degrading of the sleeve material, whereby the ports  54   d  become open (i.e., exposed) and the gases expelled into the low-pressure chamber, comprised of chambers  24  and  38 . 
         [0090]    The delay sleeve  56  may be comprised of a polymeric material, such as nylon, polyurethane, or a polypropylene, or a metal, such as brass or aluminum. 
         [0091]    When the projectile  14  and shell casing  12  are assembled, a low-pressure chamber  24  and  38  is formed behind the projectile body  34 . In such assembly, the forward end  54   b  of the gas diffuser plug  54  is spaced axially rearwardly and away from the rearward end  34   e  of the projectile  14 . The cup-shaped rearward chamber  38  of the projectile  14  is coaxially juxtaposed above and about the top  54   b  of the gas diffuser plug  54 . 
         [0092]    The assembly of the projectile  14  and the nose  16  is nose heavy, such that the projectile assembly will fly and impact nose first while describing a desired ballistic trajectory. That is, the mass center, or center of gravity of the projectile assembly, is forwardly and proximate to the head  48  of the nose  16  and the projectile assembly will not tumble in flight. In general, in the embodiment shown, the mass center is located proximate to the interface between the end face  48   c  of the nose head  48  and the front end face  34   d  of the projectile body  34 , against which the nose head  48  seats. 
         [0093]    According to this invention, the nose may also be configured to carry a special payload, in the form of a scatterable or dispersible substance, such as tear gas, dye, UV fluids, or other non-lethal material. 
         [0094]    Referring to  FIG. 5 , the non-lethal ammunition is as described above, and the nose, generally indicated by the reference number  116 , is substantially on the exterior identical to the nose shown and described herein above. According to this embodiment, the nose  116  is generally cylindrical and includes a shaped head  148  and a body member  150 , the head fitted to the body to form a unit having substantially the same size and shape as the nose  16 . When assembled together, the head and body  148  and  150  are coaxially arranged on a common axis, which axis is aligned with the geometric axis “A” when the nose  116  is assembled to the forward end portion of the projectile body  34 . 
         [0095]    The shaped head  148  is cup-shaped and includes an interior chamber  149 . The head  148  includes exterior and interior surfaces  148   a  and  148   b , respectively, a flat forward end face  148   c  adapted to face forwardly, and a flat end face  148   d  adapted to face rearwardly and seat against the forward end  34   d  of the projectile body  34 . A rounded transition surface connects the exterior surface  148   a  to the forward end face  148   b  to improve the flight ballistics when the projectile moves through the air. 
         [0096]    The body member  150  includes an annular collar  151 , which includes a rearwardly facing support surface  151   a  and exterior cylindrical surface  151   b . The support surface  151   a  seats upon the forward end  34   d  of the projectile body  34 . The exterior cylindrical surface  151   b  is dimensioned to be fitted within the chamber  149  and engage the interior surface  148   b  of the chamber  149 . 
         [0097]    The nose  116 , when assembled, is adapted to be removably mounted to the projectile  14  and form an end closure to the forward chamber  40 , much as shown and described as regards the one-piece nose  16  herein above. Further, the nose  116  is formed of a rupturable material. 
         [0098]    A dispersible medium, such as an inert powder or tear gas, shown by the reference numeral  153 , or like material that scatters upon bursting impact of the nose, is provided in the chamber  149  when the head and body members  148  and  150  are united. For clarity, a portion of the material  153  is cut-away to show the interior cup-shaped chamber  149  formed within the nose  116 . 
         [0099]    In order to fire the ammunition  10 , in operation, the projectile  14  and the nose  16 , or  116 , are preassembled. The rearward end  34   a  of the projectile assembly is loaded into the chamber  24  of the shell casing  12 , which casing is preloaded with the propellant or propelling charge, and which propellant insert seals the expansion chamber  30  and the bottom of the casing  12 . The shell casing and projectile assembly are loaded into the grenade launcher for firing. 
         [0100]    Upon firing, turning to  FIG. 4 , the propellant is exploded in the high-energy expansion chamber  30 , burnt high-energy propellant gases fill the interior cavity  54   c , the delay sleeve  56  is degraded and the vent holes  54   d  opened, and the burnt gases radially diffused into the low-pressure chamber  24  and  38  behind the projectile  14 . The gases enter the cup-shaped chamber  38  and uniformly distribute against the annular wall  38   a , whereupon the projectile assembly is issued from the casing. 
         [0101]    It is to be, thus, appreciated by interchangeability of the nose, payload, and projectile body, the type of ammunition defined by the projectile can be altered and the cost of manufacture greatly reduced. 
         [0102]    Additionally, the gas diffuser plug  54  does not have to be discarded after use. The delay sleeve  56 , although burnt by the explosion gases, may simply be replaced with a new delay sleeve. Further, the material selected for the delay sleeve enables the user to control the burn time before the gases are converted from high to low velocity expulsion. 
         [0103]    Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents