United States Patent 1 Rausing 1 1 CARTRIDGE FOR FIREARMS  Inventor: Gad Anders Rausing, Lund, Sweden 173] Assignee: Ladeo Enterprises Limited, Lund,
Sweden  Filed: Apr. 16, 1973  App1.No.:351,313
 Foreign Application Priority Data Aprv 20. 1972 Switzerland 5163/72 52 U.S. Cl. 102/3s; 1o2/93; 1o2/Drc. 1  Int. Cl. F42h 5/02  Field of Search 102/38. 93, DIG. 1. DIG. 7
 References Cited UNITED STATES PATENTS Ericson 102/93 51 May 13, 1975 2,423.453 8/1947 Howe 102/93 X 3.033.116 5/1962 Gritcher ct a1. 102/38 X 3.107.615 10/1963 Brady 102/93 X 3.125.957 3/1964 Lipinski v 102/38 X 3.148.472 9/1964 Hegge et a1... 102/93 X 3.262.391 7/1966 Shoher 102/93 3.318.244 5/1967 Rostoci 102/93 X 3.427.648 2/1969 Manning et a1 102/93 Primary [iramincr-Benjamin A. Borchelt Assislan! E.\'umim'rH. .1. Tudor Allurm'y. Agent. or Firm-Pierce, Scheffler & Parker  ABSTRACT A cartridge for a firearm comprises a projectile having a cross-sectiona1 area smaller than that of the bore of the weapon,the projectile being provided with a shoe the size of which fits into the bore of the weapon.
4 Claims, 3 Drawing Figures CARTRIDGE FOR FIREARMS The present invention relates to a cartridge for firearms, comprising a projectile the cross-sectional area of which is smaller than the cross-sectional area of the bore of the arms, in conjunction with which the cartridge is intended to be used.
Experiments have lately been carried out in arms technology with so-called subcaliber projectiles, that is to say projectiles whose cross-sectional area is smaller than the bore of the arms by means of which the projectile is to be shot off. These subcaliber projectiles are usually called flechettes and can best be compared to miniature darts, which are often provided with fins so as to stabilize the trajectory and consequently achieve better accuracy of fire. The reason for wanting to change over from conventional projectiles to flechettes is among other things, that it so becomes possible to achieve flatter trajectories and lower projectile weight. The problem which arises when conventional projectiles are replaced by flechettes is that of obtaining a sufficiently large propelling surface for the powder gases without such devices for obtaining a large propelling surface bringing about increased air resistance in the trajectory.
It is known in itself to use flechettes as projectiles in small arms ammunition and automatic arms ammunition. To achieve sufficient firing range and effect such flechettes must have a starting velocity which is as high as possible, in most cases 1.000-l.500 m/sec, which can be compared with approx. 700l.000 m/sec for conventional projectiles. Higher muzzle velocities than 900-l.000 m/sec can hardly be achieved in conventional arms with conventional projectiles other than by the use of a very long barrel and very high propelling pressure, which of course in turn decisively affects the appearance and the construction of the arms. For one thing, for example, the material thickness in the barrels must be relatively great, for another thing the locking mechanism in the bolt must be made very strong so as to stand the high pressure, which results in a heavy and clumsy weapon, and furthermore, since the temperature gradient in the inner layer of the barrel may go up to several thousand degrees and the gas velocity is very great, the wear of the barrel is enormous and its life is short.
Owing to the low weight of the flechette it is possible, by retaining the same caliber and by using so-called sabots, that is to say plates or the like which fit into the bore of a normal weapon and which are so fixed to the flechette that the same is separated from the sabots directly outside the muzzle, to achieve high projectile velocities at low loading and consequently at moderate pressure. The difficulties consist here in being able in a sufficiently certain, and from firing to firing identical, manner to separate the sabot from the projectile. It is known from artillery technique to provide a subcaliber, dartlike projectile with a sabot which is fixed to the projectile by a thin metal strip. The metal strip is so dimensioned that the high powder gas pressure directly after the projectile has left the muzzle breaks it off, whereby the sabot is separated from the projectile.
A corresponding device is hardly practical for application on cartridges in small arms ammunition, mainly because the cartridges in such a case would become enormously expensive to manufacture, but in accordance with the invention the problem can be solved in a different manner, in that the sabot is made multipart and the parts of the sabot are held together before the firing of the cartridge by a combustible body, which burns up completely before the projectile has left the muzzle of the arms.
An embodiment of the cartridge in accordance with the invention will be described in the following with reference to the enclosed schematic drawing, in which FIG. 1 shows a caseless cartridge with a flechette projectile,
FIG. 2 shows a normal cartridge provided with case with flechette projectile, and
FIG. 3 finally shows a view of the cartridges according to FIGS. 1 and 2 seen from the front.
The cartridge shown in FIG. 1 consists of a needleshaped projectile, a so-called flechette l which is provided with a recess 7 to accomodate a sabot 2 and with a fin 4.
The sabot 2 comprises two or more sections which are combined to a unit which ressembles most closely an annular washer whose inside part is adapted to be accomodated in the recess 7 of the flechette 1. The sabot 2 consists appropriately of metal or some metal alloy, e.g., steel or brass, and the outer circular surface 8 must be machined to a surface fineness and true measurement which correspond to the demand made in respect of the achievement of complete tightness against the walls in the bore of the weapon. The sabot 2 has an annular recess 6 which extends through all the parts of which the sabot is composed. In the example shown in FIG. 1 the parts of which the sabot is composed are held together with the help of a compressed powder mass 3 which at the same time constitutes the propellent charge of the cartridge. At the rear end the cartridge is provided in a known manner with a sealing washer 5 which can be manufactured of a combustible material, which however has to burn more slowly than the powder charge since the seal 5 must maintain its tightening function during the whole time whilst the powder charge 3 is burning.
The cartridge shown in FIG. 1 is thus not provided with any case outside the projectile, the sabot sealing device being held together by the cast powder mass 3. A cartridge of this type is of course cheaper in its manufacture than a cartridge with case, and it will moreover be appreciably lighter especially as the weight of the projectile in this case will be appreciably lower than the weight of a normal projectile.
In FIG. 2 is shown a variant of the cartridge shown in FIG. 1 in accordance with the invention, and in the example shown here the cartridge is provided with a case 9 of brass or similar material, which case in a known manner is provided with propellent charge and igniting device for the powder charge accomodated in the case 9. The projectile l is provided as in the previous example with a recess 7, in which is arranged the sabot 2 and as in the earlier described case the sabot 2 consists of two or more sections, which are combined into a unit and which sections 2 are held together by a strip 10 of combustible plastic material.
In FIG. 3 is shown a view from the front of the projectile 1 with sabot 2, which in the case illustrated is divided into three sections, namely 2a, 2b and 20 which are arranged so that they are fitted against one another with a good fit.
When the cartridge is to be fired it is accomodated in known manner in the cartridge chamber of the weapon whereupon the propellent charge 3 is ignited,
either by means of a conventional ignition device or e.g., electrically by means ofa hot wire arranged in the propellent charge, the connection ends of which are accessible from the outside of the cartridge.
When the propellent charge 3 is ignited it burns very rapidly, cumbustion gases being formed in the cartridge chamber which produce an enormously high pressure. Owing to the locking of the weapon at the breech of the barrel these combustion gases cannot stream backwards but they exert instead a pressure on the sabot 2 and the projectile l, which brings about that the projectile 1 and the sabot 2 together are launched forward through the bore of the weapon whilst they are strongly accelerated so as to obtain a velocity of approx. l.O-l.500 m/sec at the muzzle of the weapon. The reason for the acceleration being greater than that of normal projectiles is of course the low weight of the projectile.
When the projectile has reached the muzzle the propellent charge 3 has been completely burnt up, which implies that the sabot 2 shown in FIG. 1 is no longer held together by the propellent charge 3 but that its parts 2a, 2b and 20 can be separated from one another. This occurs when the projectile leaves the muzzle of the weapon in that the parts 2a, 2b and 2c of the sabot are blown off the projectile 1 by the powder gases discharging from the bore. The parts of the sabot are slowed down promptly by the air resistance and fall to the ground, whilst the projectile 1 alone continues its trajectory, and owing to the small cross-sectional area of the projectile and its high starting velocity a very great firing range and a very flat trajectory can be achieved. By virtue of the presence of the fins 4 the projectile is stabilized in the trajectory, which brings about that the projectile very accurately maintains its trajectory and that the accuracy of fire will be high.
At the firing of the cartridge in accordance with FIG. 2 the propellent charge in the case 9 is ignited and the projectile 1 together with the sabot 2 is in tight contact along its cylindrical surface 8. By virtue of the high temperature of the powder gas the plastic ring or plastic strip 10 which holds together the parts of the sabot 2 will burn and the plastic strip 10 is dimensioned in such a manner that it will be completely burnt up before the projectile 1 has reached the muzzle of the barrel. Owing to the fact that the parts of the sabot 2 are in close contact with each other and bear on the one hand against the wall of the barrel, and on the other hand against the recess 7 of the projectile, the parts cannot separate when the sabot is still inside the barrel oflthe weapon, even though the plastic strip 10 has been burnt up, but as soon as the projectile l and the sabot 2 have left the bore the discharging gases will blow off the parts 2a, 2b and 2c of the sabot from the projectile 1, which of course completes its projectile trajectory.
It was found that cartridges in accordance with the invention are very reliable in their function and are moreover cheap to manufacture, and it is possible consequently to use cartridges in accordance with the invention to achieve a firing range, accuracy of fire and effect of the projectile which cannot be achieved with conventional cartridges.
Naturally it is possible within the scope of the concept of the invention to modify the appearance of the projectile as well as of the sabot, and as mentioned in the description, the ignition of the propellent charge for example can be done in a number of different ways of which here only a few have been mentioned.
l. A cartridge for firearms comprising a projectile having a cross-sectional area smaller than the crosssectional area of the bore of the weapon in which the cartridge is to be used and provided with an annular recess thereabout, a plurality of metal sabot sections forming together a sabot surrounding and engaging the annular recess of said projectile, said sabot sections when assembled including an annular recess on the rear face of said sabot, the outer circumference of said sections forming a close seal with the bore of the weapon and means of combustible material engaging the annular recess in the rear face of the assembled sabot sections for securing said sabot sections together around said projectile, said combustile securing means being consumed by combustion when the weapon is tired before the projectile leaves the muzzle of the bore whereby the sabot sections disengage from said projectile after leaving the bore of the weapon.
2. A cartridge as claimed in claim 1 wherein said combustible securing means consists of a plastic material.
3. A cartridge as claimed in claim 1 wherein said combustible securing means consists of a mass of pressed powder to assist in propelling the projectile from the bore of the weapon.
4. A cartridge as claimed in claim 1 and further comprising radial fins provided at the rear of said projectile.