Patent Application
20070144393
This invention relates to caseless ammunition to be used in firearms especially small arms such as rifles and pistols. This type of ammunition has the propellant stored within the bullet itself rather than in a case that must be expelled from the firearm after the firearm is discharged.
The ammunition currently available generally consists of four parts a bullet, a case, a propellant, and a primer. The bullet is generally molded of lead, may have a coating of copper or other material, be generally cylindrical in shape, be of such diameter as to pass through the barrel of a firearm, be of such contour that its sidewall will have an interference fit with the case and the opposite end generally being pointed. The case, usually made of brass is used to contain a propellant. The case is relatively expensive, has a flange that prevents even stacking of the ammunition, and it must be ejected from a firearm so that a subsequent round can be loaded into the barrel.
Therefore, eliminating the case would result in lower cost ammunition. Caseless ammunition is shown in U.S. Pat. No. 4,187,781 granted to Flanagan. In this invention it is composed of two parts a bullet (projectile) and a propellant. The propellant in this disclosure is molded in several layers on the exterior of the projectile, with the outer layer being a material that resists ignition by heat that might be encountered in the barrel of a firearm that had recently been fired one or more times.
Caseless ammunition is also disclosed in patents to Julien U.S. Pat. No. 6,581,522 and Infatino U.S. Pat. No. 3,815,503. In both of these patents the bullet or projectile is used to contain the propellant. The propellant is sealed within the bullet with an end cap that also contains the primer. Further, the projectile is made of such material that it is meant to expand when the propellant is ignited. While the intended purpose of this expansion is to cause the outer surface of the projectile to contact the rifling in the barrel of the firearm, the unintended consequence is the high frictional drag created as the projectile moves down the barrel. This friction generates heat, slows the velocity of the projectile, and increases wear of the barrel.
To increase the velocity of the bullet, ammunition in the current state of the art uses a case that is much larger in diameter than the bullet. At the interface of the case with the bullet the case is tapered down to obtain an interference fit with the bullet. The increased diameter of the case provides for an increased quantity of propellant to increase the velocity of the bullet.
Generally, the propellant used in current ammunition is smokeless gunpowder. Highly explosives materials are not used because the exothermic chemical reaction of their ingredients occurs much more quickly after ignition than that experienced with gunpowder. Therefore, very high pressure is built up within the case of ammunition using high explosives as a propellant. This pressure becomes so great because the bullet is held in place by frictional contact with the case and inertia, thus, limiting the volume of space into which the gas given off by the exploding propellant can expand. This very high pressure can cause the case to expand and become lodged in the barrel and even damage the barrel itself. To remedy this condition by using a smaller quantity of these highly explosive materials to avoid the build up of this high pressure results in an inadequate quantity of propellant to propel the bullet to a target. The use of a small quantity of highly explosive material to propel a bullet at the same or greater velocity as one propelled by ammunition having a case with increased diameter containing gunpowder would advance the state of the art.
The object of the present invention is to provide caseless ammunition for firearms where the bullet contains the propellant, the bullet is propelled at a high velocity, the bullet does not change dimensionally with the firing of the propellant, one or more than one type of propellant can be used, the bullets can be evenly stacked because they do not have a flange, and the bullet can easily be extracted from the barrel if so desired.
One of the main functions of the case is to contain the propellant for the ammunition. This invention proposes that the bullet be hollow so as to contain the propellant. A solid propellant would be preferred as it could be molded directly into the bullet and be contained therein. A propellant having the viscosity of putty would also be desirable A powdered or liquid propellant could also be used but would require a device be used to seal the propellant in the bullet. Such device would be expended during the firing of the propellant.
The amount of propellant required to propel a bullet from its initial position in the firearm to the intended target at a high rate of speed is affected by the weight of the bullet. This disclosure requires that the propellant be contained within the bullet. Because the quantity of propellant contained within the bullet is less than that in a case, the explosive force of this propellant must be much greater than that of case type ammunition.
The preferred material for the bullet this disclosure is steel because of its high strength and relatively low cost. The thickness of the wall of a steel or other high strength material bullet would be much thinner than that of a low strength material such as lead, for withstanding the explosion of the propellant without significant dimensional changes. The choices of materials for the bullet and its optimal dimensions are within the state of the art of the engineering disciplines. The diameter and length of the cavity for containing the propellant will be determined by the choice of materials for the bullet and the type and quantity of the propellant.
A suitable coating could be applied to the exterior of a steel bullet to minimize the effects of its travel down the barrel with regard to damaging the interior of the barrel of the firearm. The ideal coating would easily conform to the rifling in the barrel and have lubricating characteristics so as to reduce friction as the bullet moves down the barrel. Tin, lead, zinc or alloys of these elements could be used.
The use of a solid propellant that could be molded into the bullet is the desired form of propellant of this disclosure. While a solid propellant is deemed desirable, it is not a limiting factor of this invention. Other forms of a propellant can be utilized and still remain within the scope of this invention. Namely, this disclosure is directed toward ammunition having only two components, a bullet and a propellant. Further, this invention discloses a bullet with a propellant contained therein that is expended explosively to propel the bullet from the barrel of a firearm.
The present invention has the propellant contained within the bullet and proposes one or more types of propellant may be contained therein. For example a bullet could have a propellant composed of three layers that would ignite sequentially; the first layer would act as a primer; the second layer could accelerate the bullet; and a highly explosive third layer would then be ignited to further accelerate the bullet to a very high rate of speed. The action of the first two layers is available in current ammunition having a case while the action of the third and possibly subsequent layers is available when such propellant is within the bullet itself Ignition of the third and possibly subsequent layers of propellant may occur after the bullet has departed the barrel of the firearm but preferably the entire quantity of propellant will be expended while the bullet is within the barrel of the firearm. This invention discloses that when a series of propellants within the bullet are ignited in sequence, a propellant having very high explosive characteristics can be used effectively when it is ignited after the initial propellant has moved the bullet some distance down the barrel. That is the bullet has moved forward from the bolt with the ignition of the initial propellant, thereby, providing a large volume of gas into which the gas from the ignition of the highly explosive propellant can expand thus reducing tensile stress within the bullet. High explosives were not practical for use as a propellant before because the quantity of propellant needed to propel the bullet from its initial position in the firearm to the target was such that ignition of this quantity of propellant could damage the firearm. This invention discloses that high explosives can now be used effectively because they can be ignited after the bullet has had one or more propellants ignited to propel the bullet some distance down the barrel of the firearm. The overall quantity of the explosives layered within the bullet should result in the bullet being propelled at a velocity and striking force equal to or greater than that for ammunition currently in use.
The ignition of the propellant may be initiated by impact, spark, heated probe, or other means as is necessary to initiate chemical reaction of the propellant or first layer of propellant what ever the case may be. This firing mechanism would be incorporated into the modification of existing firearms and or design of new firearms that would use the ammunition in this invention.
Because ammunition in this invention does not have a case, the step in the continued firing of a firearm that requires the ejection of the case of the round just fired so that the subsequent round be loaded, may be omitted. When firing an automatic firearm having one step such as the ejection of a case being omitted the rate of firing should increase and this could be a further advantage of this invention. Further, elimination of the need to eject a case from a spent round could result in the firearm jamming less frequently.
From a practical standpoint the present invention must address the ejection of a round of ammunition from the barrel because it is a dud; and the positioning and retention of the bullet in the barrel prior to being fired. While these design requirements must be considered for the firearm itself, modification of current firearms to use the caseless ammunition could be as simple as using a magnetized bolt. If the bullet is manufactured of steel a magnetic bolt would retain the round in the barrel due to the magnetic attraction of the bullet to the bolt. Likewise, if a magnetized bolt were manually retracted, it would extract a steel bullet from the barrel and eject it just as it does with mechanical contact of present ammunition. If the bullet is not composed of a material that is attracted to magnets, means for mechanically contacting the bullet such as a circumferential groove in the exterior wall of the bullet could be contacted by cooperating means in the firearm, that is manually operated, to eject the unspent round of ammunition. Further the bullet could be retained and indexed within the barrel by a short length of spring steel wire contacting the nose of the bullet, near its point. When the weapon is fired forcing the bullet forward, the spring wire would flex out of the way with at least one end retracting into a channel in the barrel. One could anticipate an engineer designing a retaining device as described above.
The design of the tip of the bullet, the diameter of hollow portion used to contain the propellant, and the composition, position, type, and/or shape of the propellant are factors to be considered when the propellant can be ignited by the impact of a firing pin. One would not want the tip of one bullet to fire another bullet by casual contact with the propellant. Therefore the fill level of propellant in the bullet must be established with regard to how far the point of another bullet could enter the propellant chamber.
Likewise, heat resistant layers or coatings on the bullet can be used to prevent accidental firing of a bullet due to heat build up in the firearm. While heat causing accidental firing to happen is remote because steel is less conductive of heat than brass, exposure of the propellant at the end of the bullet may require that the propellant be insulated at the exposed end.
The preferred version of this invention would be a steel bullet having a cavity that is filled with a propellant that is semi solid, like putty, solid, or becomes generally solid after introduction into the cavity. Further the propellant should not be susceptible to ignition by impact encountered in normal handling or by the heat normally encountered in its usual ambient. The propellant would be easily ignited by a heat source such as a spark, a heated firing pin, laser, etc. or by specific high impact such as being struck by the firing pin in a firearm.
The elimination of a relatively expensive brass case; using a relatively less expensive material such as steel for the bullet; the using of layers of multiple types of propellant (especially high explosives) within a bullet; having a groove on the exterior of the bullet for its extraction from the barrel; and having a hard metal bullet with an exterior layer of soft metal for contacting the rifling in a barrel, are some of advantages of this invention. Current firearms could be easily modified to use this ammunition and new firearms could be produced to eliminate the step in the continuous firing sequence that ejects the spent case, thereby effectively increasing the rate of fire, another advantage. A wide variety of high potency explosives that cannot be used in current ammunition because they cause deformation of the case such that the firearm becomes jammed, could be utilized in the current invention where the propellant is contained within a comparatively strong steel bullet and because the highly explosive propellant could be ignited when the bullet has moved some distance down the barrel or even after the bullet has exited the barrel
When the caseless ammunition is positioned in the end of the barrel of a firearm and the propellant 3 is ignited, the propellant will be expanded through exothermic chemical reaction, causing the bullet 2 to rapidly travel down the barrel and exit the firearm. As there is no case to eject from the barrel of the firearm, a subsequent round of caseless ammunition can immediately be positioned in the barrel of the firearm.
The bullet may have a circumferential groove 7 that could be used to cooperate with a device in the firearm to retain the bullet in its barrel after the bullet has been placed there. This device in the firearm would not deter the movement of the bullet when the firearm is fired. The depth of the groove and the angle of the sides of the groove are variable.
The caseless ammunition 1 may have more than one propellant contained therein as shown in
