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(11) | EP 0 238 155 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Ammunition for firearms |
| (57) An ammunition for firearms adapted to be used in handguns, and particularly in automatic
pistols, comprising a case (13) containing a propellent powder load and a bullet (15)
having an open cavity (7) and partially inserted in the case (13), wherein the bullet
(15) includes two projecting rings (2, 3) in the zone of the cavity (7) of the bullet,
a first (2) of said rings being located at the rear part of the bullet and a second
(3) of said rings being located spaced apart towards the front part of the bullet,
a space being defined between the case (13) and the wall (10) of the bullet between
both rings, said space being communicated with the cavity (7) of the bullet and with
the interior of the case (13); the case may include at least one radially inwardly
projecting canelure (6) located between both rings of the bullet, with the canelure
(6) having an inner diameter smaller than the outer diameter of any of said rings.
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Background of the invention
Field of the invention:
[0001] This invention relates to ammunitions for firearms such as handguns and more particularly for automatic pistols where the volumetric capacity of the ammunition case is predetermined in relationship to the structure, resistance and configuration of the pistol, and where the length of the case-bullet structure as well as the peripheral bullet shape cannot be changed. According to the present invention the kinetic energy of such an ammunition is considerably increased by decreasing the friction generated between the surface of the bullet and the inner surface of the barrel and by allowing the internal case volume to increase in a particular manner to allow a much larger propellent load.
[0002] The invention provides for the manufacture of very light weight bullets, having standard dimensions and being made of relatively hard materials, such as mild steel, compared to lead jacketed bullets.
Description of the prior art:
[0004] Military and police forces require for their handgun ammunition having simultaneously the following features:
- Very high stopping power
- Very high metal piercing capacity
- Low penetration on human targets
- High speed within a limited range, beyond which the bullet should rapidly lose its speed. Therefore beyond the range, the probability of hurting bystanders is reduced.
[0005] Conventional ammunitions having lead bullets covered with a thin metal case usually do not comply with any of the former requirements.
[0006] Deformable bullets which expand upon impacting the target have a high stopping power, and do not overpenetrate the human body, but their metal piercing capacity is very low and their target range is excessive for police use. These bullets may not be employed by military forces, because of international conventions, that forbides the use of deformable bullets.
[0007] Bullets loaded with very small shots which are released on impact, have a very high stopping power, but their metal piercing capacity is negligible, and they lose their efficiency if they hit thin metal or glass. Beside that, their range is excessive for police use.
[0008] A relatively recent development consists in the use of very light weight bullets made of brass or copper. The kinetic energy of a fired bullet is roughly proportional to the cartridges propellent powder load, so the lighter the bullet, the higher the speed.
As stopping power and metal piercing capacity are exponential functions of speed, both are improved. As the penetration on human targets and range are functions of the bullet's ballistic coefficient, lighter bullets with a low ballistic coefficient do not overpenetrate and have reduced target ranges. The definition of the ballistic coefficient is:
Cb = Cs
wherein Cs= shape coefficient, the value of which depends on the shape of the bullet,
m = mass of the bullet,
a = cross-section of the bullet.
[0010] This last category of bullets made with brass or copper has several design restrictions, which are overcome by the present invention.
[0011] For a given material, the only way to reduce the weight of a bullet without changing its dimensions is to make it hollow. Bullets having an open base cavity present several problems on high pressure weapons. The maximum pressure within the barrel is generated, when the bullet has just started moving and its speed is very low. At this low speed, pressure on the bullet's cavity increases the friction between the bullet and the barrel which in turn retards the bullet, increasing the pressure. Thus, not only the maximum pressure values become higher, but they become irregular because of the feedback effect between pressure and friction. In other words, the higher the pressure, the higher the friction which in turn increases the pressure. Compared with plain bullets, on a series of shots, the thin walled cavities will produce maximum pressure peak records, of a range of 10% increase.
[0012] Another problem arises in short-barrel high pressure weapons. When the bullets exit the barrel, the pressure inside the bullet's cavity can be very high, 500 bar for a 90 mm barrel, firing a 9 mm Luger. As the bullets exit the gun barrel, they lose the peripheral support offered by the barrel and the hollowed section may be blown up, diverging the bullet from its trajectory.
[0013] Because of the above reasons, it is impossible to use thin walled bullets in order to have lightweight bullets. Thus bullets having cavities, must nevertheless have a sufficient wall thickness.
[0014] For lightweight high speed bullets, with a good metal piercing capacity, it is necessary to employ metals with a density close to 8, like copper, brass or mild steel. These metals are relatively hard and these bullets require a much higher force to be started on the barrel rifling than metal jacketed lead ones. A 9 mm Luger metal jacketed bullet, requires a force of about 100 daN while a plain brass requires 300 daN and a steel one more than 600daN.
[0015] A high starting force has the same effect on pressure as increasing the bullet weight. A 9 mm Luger plain brass bullet will have a maximum pressure 3% higher than a conventional metal jacketed one. A steel one, hard enough to get stuck on the rifling would increase pressure to the extent of blowing the barrel.
Sumary of the invention:
[0016] In order to overcome the above drawbacks, the present invention provides an ammunition for firearms wherein the bullet, after having left its case exposes a reduced bullet friction surface because of two narrow rings on the said bullet. The bullet, upon firing, while first being clamped in the case, is capable of sliding freely along the case before one of said rings engages a front canelure or ring-recess of the case, increasing thus the case volume, which in turn reduces the maximum pressure peak on the barrel. Since for a given powder load, the maximum pressure becomes reduced, it is possible to increase the propellent charge and therefore the kinetic energy, without exceeding the allowed maximum pressure value. The bullet according to the invention has a large cavity opened at the bullet's base, to reduce its weight and to allow for an increased propellent powder load. The above explained negative effects of the pressure difference between the inside and the outside of the bullet's cavity are eliminated, by equalizing the pressure within the cavity and the outside of the bullet, through holes or slots communicating the outer surface portion located between the rings of the bullet, with the inside of the cavity and the case. A higher starting force has the same effect on pressure as increasing the bullet's weight.
[0017] As for a bullet of a predetermined caliber, weight and material, the starting forces are proportional to the surface which is to be deformed by the helical rifling of the barrel of the guns, the obvious solution, to reduce the starting forces is to reduce the surface to be deformed. According to the present invention, the bullets body diameter is reduced to the inner rifling diameter and the two narrow rings -a first or rear ring at the bullets base and a second or front ring at a sufficient distance from the first one- have an outer diameter equal to the inner diameter of the barrel's bore diameter and will be the only part of the bullet to be deformed by the rifling thereof.
[0018] It is well-known that a bullet requires upon firing, a certain force to pull out of the case. This required force allows the pressure to build up before the bullet starts moving allowing the propellent powder to ignite completely. If the required force is low, part of the ignition takes place after the bullet has pulled out becoming irregular, not reaching the correct peak value and so delivering lower and irregular combustion values. The present invention provides a way to control the bullet pull out force of the casing and thereby achieving a better powder ignition. The force necessary to move the bullet along the case will depend on the friction which becomes generated between the bullets surface and the case. A bullet merely having two spaced apart narrow rings, will have a low friction force on the case, and two new problems will arise: 1) The bullet may be accidentally pushed into the case, thereby increasing the maximum pressure, when fired. 2) The required pull out force will be too low, thereby producing an unsatisfactory combustion. To prevent the bullet to be pushed into the case, the conventional solution is a canelure formed just below the bullets base. To increase the required pull out force, another canelure is formed in front of the rear ring.
[0019] A better solution which is part of this invention is a single canelure formed below the second or front ring. This canelure will prevent the bullet to be accidentally pushed into the case. When the ammunition is fired, the bullet will move forward by a minimum pressure until said first or rear ring engages the canelure. Then the bullet will be stopped until sufficient pressure builds up to pull out the bullet by deforming the canelure. This first movement of the bullet within the case has the same effect on the maximum pressure aspect as if the case were longer for a same propellent powder load since the maximum pressure drops as the case volume increases. This pressure drop allows to increase the propellent powder load and conse quently enables to achieve a higher kinetic energy and therefore a higher speed of the bullet.
[0020] On a 9 mm Luger cartridge, if the combination at a front canelure and a rear ring is employed, the bullets movement within the case will be about 2,5 mm, increasing the case volume by 20% and reducing pressure by 15%. On a 45 ACP cartridge the movement within the case will be 5 mm, increasing the case volume by 49% and reducing presure by 30%.
[0021] Another aspect of this invention is the possibility of manufacturing bullets having thin wall portions at the zone of the hollow base, allowing the use of outstanding cavities. This invention provides a communication between the space defined between the rings and the cavity of the bullet, so that the pressure will be the same on both sides of the above referred to wall portions, whereby no wall deformation takes place. This communication may be achieved for instance by holes in the cavity wall, pertinent slots cut into the rear ring or making the rear ring of a smaller diameter than the bore of the case.
[0022] The present invention avoids the risk of the bullet blowing up when leaving the barrel. If holes are utilized which allows the gases to escape when the thin wall portions alone are still supported within the barrel.
[0023] In conclusion the present invention provides an ammunition for firearms comprising a case adapted for containing a propellent powder load and a bullet partially inserted within the case, the bullet being of the kind which has a rear part and a front part, a hollow base forming a cavity opened to the rear part of the bullet, the cavity is formed by wall portions which are relatively thin regarding the remaining body of the bullet, the improvement wherein said bullet includes, at the zone of said cavity, two spaced apart rings projecting from the outer surface of the bullet, there being a first of the rings which is located at the rear part of the bullet and a second of the rings located spaced apart from the first ring and towards the front part of the bullet, at least said second ring being in sealing contact with the case, a space which is formed between the outer surface of the bullet located between both first and second rings and the case is, at least when firing the ammunition, communicated with said cavity and the interior of said case where the propellent powder load is located.
[0024] In an other aspect of the invention provides an ammunition for firearms comprising a case having a case wall and adapted for containing a propellent powder load and a bullet partially inserted within the case, the bullet being of the kind which has a rear part and a front part, a hollow base forming a cavity opened to the rear part of the bullet, the cavity is formed by wall portions which are relatively thin regarding the remaining body of the bullet, the improvement wherein said bullet includes, at the zone of said cavity, two spaced apart rings projecting from the outer surface of the bullet, there being a first of the rings which is located at the rear part of the bullet and a second of the rings is located spaced apart from the first ring and towards the front part of the bullet, at least said second ring being in sealing contact with the case, and the case having bullet retaining means adapted to retain the bullet in position within the case, the bullet retaining means comprising a canelure radially inwardly projecting from the case wall and which extends between both rings of the bullet, the inner diameter of the canelure being smaller than the outer diameter of any of the rings.
[0025] In another aspect the invention provides an ammunition for firearms comprising a case having a case wall and adapted for containing a propellent powder load and a bullet partially inserted within the case, the bullet being of the kind which has a rear part and a front part, a hollow base forming a cavity opened to the rear part of the bullet, the cavity is formed by wall portions which are relatively thin regarding the remaining body of the bullet, the improvement wherein said bullet includes, at the zone of said cavity, two spaced apart rings projecting from the outer surface of the bullet, there being a first of the rings which is located at the rear part of the bullet and a second of the rings located spaced apart from the first ring and towards the front part of the bullet, said second ring being in sealing contact with the case, and the case having bullet retaining means adapted to retain the bullet in position within the case, the bullet retaining means comprising a canelure radially inwardly projecting from the case wall and which extends between both rings of the bullet, the inner diameter of the canelure being smaller than the outer diameter of any of the rings and a space which is formed between the outer surface of the bullet located between both first and second rings and the space is communicated with said cavity and the interior of said case where the propellent powder load is contained.
[0026] In another aspect the invention provides a bullet for an ammunition having a rear part with an open cavity, and a front part, the cavity is formed by wall portions which are relatively thin regarding the remaining body of the bullet, the improvement wherein said bullet includes, at the zone of said cavity, two spaced apart rings projecting from the outer surface of the bullet, there being a first of the rings which is located at the rear part of the bullet and a second of the rings located spaced apart from the first ring and towards the front part of the bullet, the thin wall includes, between both rings, at least one through orifice.
[0027] In another aspect the invention provides a bullet for an ammunition having a rear part with an open cavity, and a front part, the cavity is formed by wall portions which are relatively thin regarding the remaining body of the bullet, the improvement wherein said bullet includes, at the zone of said cavity, two spaced apart rings projecting from the outer surface of the bullet, there being a first of the rings which is located at the rear part of the bullet and a second of the rings located spaced apart from the first ring and towards the front part of the bullet, the first ring having an outer diameter smaller than the outer diameter of said second ring.
[0028] In another aspect the invention provides a bullet for an ammunition having a rear part with an open cavity, and a front part, the cavity is formed by wall portions which are relatively thin regarding the remaining body of the bullet, the improvement wherein said bullet includes, at the zone of said cavity, two spaced apart rings projecting from the outer surface of the bullet, there being a first of the rings which is located at the rear part of the bullet and a second of the rings located spaced apart from the first ring and towards the front part of the bullet, the first ring having at least a groove connecting the opposite sides of the ring.
Brief description of the drawings:
[0029] For a better understanding of the present invention, reference will now be made, by way of example, to the attached drawings, where several embodiments are disclosed, and which facilitates the comprehension of the principle of the invention:
Figure 1 is a side view of a prior art 9 mm bullet;
Figure 2 shows a similar prior art bullet, where the size of the friction surface has been decreased by providing two narrow spaced apart rings.
Figure 3 is a longitudinal section of a bullet including the features of the invention and having a rear open cavity connected to the outside surface of the bullet by holes;
Figure 4 shows a partial sectional side elevation of a prior art ammunition, including the bullet of Figure 2 mounted in a case and retained by canelures on both sides of the rear ring;
Figure 5 shows a partial sectional side elevation of an ammunition prior to use, according to the invention, including the bullet of Figure 3 retained by a single canelure located between both rings and adjacent the front ring;
Figure 6 shows a longitudinal section of the ammunition of Figure 5 when the firing has started and the bullet has moved until the first ring engages the canelure of the case and also showing the open cavity in the bullet,
Figure 7 shows a longitudinal section of another embodiment of the bullet of the invention, and
Figure 8 shows a rear view of the bullet embodiment of Figure 7.
Detailed description of the preferred embodiments:
[0030] On a conventional bullet d, Figure 1, the surface to be deformed by the rifling of the barrel of the fire arm is the one located between the schematically indicated plans a and b defining the body portion c .
[0031] To reduce friction between the bullet and the barrel, the diameter of the body portion c, according to a prior art development was reduced, so as to have substantially the same inner diameter of the rifling, as indicated by reference numeral 1ʹ in Figure 2. Two narrow rings having a diameter corresponding to the gun bore diameter are formed on the bullet 1, more particularly a first or rear ring 2 at the bullet's base and a second or front ring 3 at a suitable distance to allow a correct assembling with a case. Both rings 2 and 3 will provide a guidance for the bullet after having left the case 13, and the front one 3 will provide the seal in the barrel (not shown) of the gun.
[0032] This bullet 1 having only two narrow rings 2, 3 in contact with the wall of the well known cylindrical case (not shown) will provide for a very low pull out force. To increase the pull out force to acceptable values, for example 75 daN, a canelure 4 is formed in the case 14, adjacent the rear ring 2, as shown in Figure 4. To prevent the bullet 1 to accidentally be pushed into the casing 14, another canelure 5 can be formed at the other side of rear ring 2, opposite the canelure 4.
[0033] According to the invention and as shown in Figure 5, the ammunition comprises a case 13 and a bullet 15 partially fit therein. Bullet 15 comprises a front part and a rear part. A single canelure 6 is formed in case 13, adjacent the front ring 3. This single canelure 6 will prevent the bullet 15 to accidentally be pushed into the case 13 and when the ammunition is fired, the bullet 15 will first move forward with a minimum pressure, about 20 bar, until the rear ring 2 located at the rear part engages the front canelure 6 as shown in Figure 6. The bullet 15 will then be retained until pressure builds up to about 120 bar pulling out the bullet 15 by overcoming the resistance offered by the canelure 6.
[0034] In order to obtain the pressure compensation to which reference was made above, so as to avoid deformation of thin wall portion 9, while being within the barrel (not shown), cavity 7 (Figures 3 and 6) has to be connected to the space defined between outer surface 10 of wall portion 9, and case 13 so that the pressure will be the same inside and outside cavity 7. Such a pressure compensation will avoid outward radial deformation of thin wall portion 9 and therefore will avoid a frictional contact thereof with the barrel.
[0035] As shown in the alternative embodiment of Figures 7 and 8, another way of communicating cavity 7 with the outer surface 10 of wall portion 9, is to provide notches 12 cut into the rear ring 2a and part of the wall portion 9.
[0036] Still another manner of performing such a communication is to provide a rear ring (not shown) having a smaller diameter than the inner diameter of case 13 and the gun barrel bore (not shown) so that the rear ring will not seal against the inner surface of the gun barrel. This embodiment may be readily understood by anybody skilled in the art, without specific illustration.
1. In an ammunition for firearms comprising a case adapted for containing a propellent
powder load and a bullet partially inserted within the case, the bullet being of the
kind which has a rear part and a front part, a hollow base forming a cavity opened
to the rear part of the bullet, the cavity is formed by wall portions which are relatively
thin regarding the remaining body of the bullet, the improvement wherein said bullet
includes, at the zone of said cavity, two spaced apart rings projecting from the outer
surface of the bullet, there being a first of the rings which is located at the rear
part of the bullet and a second of the rings located spaced apart from the first ring
and towards the front part of the bullet, at least said second ring being in sealing
contact with the case, a space which is formed between the outer surface of the bullet
located between both first and second rings and the case is, at least when firing
the ammunition, communicated with said cavity and the interior of said case where
the propellent powder load is located.
2. The ammunition for firearms according to claim 1, wherein the wall portions of
the bullet defining the cavity include at least one through orifice communicating
said space and the cavity of the bullet.
3. The ammunition for firearms according to claim 1, wherein said space is communicated
with the interior of the case through at least a groove formed in said first ring.
4. The ammunition for firearms according to claim 1, wherein the exterior diameter
of said first ring is smaller than the inner diameter of said case, whereby said space
between said rings is communicated with the interior of the case.
5. In an ammunition for firearms comprising a case having a case wall and adapted
for containing a propellent powder load and a bullet partially inserted within the
case, the bullet being of the kind which has a rear part and a front part, a hollow
base forming a cavity opened to the rear part of the bullet, the cavity is formed
by wall portions which are relatively thin regarding the remaining body of the bullet,
the improvement wherein said bullet includes, at the zone of said cavity, two spaced
apart rings projecting from the outer surface of the bullet, there being a first of
the rings which is located at the rear part of the bullet and a second of the rings
is located spaced apart from the first ring and towards the front part of the bullet,
at least said second ring being in sealing contact with the case, and the case having
bullet retaining means adapted to retain the bullet in position within the case, the
bullet retaining means comprising a canelure radially inwardly projecting from the
case wall and which extends between both rings of the bullet, the inner diameter of
the canelure being smaller than the outer diameter of any of the rings.
6. In an ammunition for firearms comprising a case having a case wall and adapted
for containing a propellent powder load and a bullet partially inserted within the
case, the bullet being of the kind which has a rear part and a front part, a hollow
base forming a cavity opened to the rear part of the bullet, the cavity is formed
by wall portions which are relatively thin regarding the remaining body of the bullet,
the improvement wherein said bullet includes, at the zone of said cavity, two spaced
apart rings projecting from the outer surface of the bullet, there being a first of
the rings which is located at the rear part of the bullet and a second of the rings
located spaced apart from the first ring and towards the front part of the bullet,
said second ring being in sealing contact with the case, and the case having bullet
retaining means adapted to retain the bullet in position within the case, the bullet
retaining means comprising a canelure radially inwardly projecting from the case wall
and which extends between both rings of the bullet, the inner diameter of the canelure
being smaller than the outer diameter of any of the rings and a space which is formed
between the outer surface of the bullet located between both first and second rings
and the space is communicated with said cavity and the interior of said case where
the propellent powder load is contained.
7. The ammunition for firearms according to claim 5, wherein said canelure is adjacent
said second ring of the bullet.
8. A bullet for an ammunition having a rear part with an open cavity, and a front
part, the cavity is formed by wall portions which are relatively thin regarding the
remaining body of the bullet, the improvement wherein said bullet includes, at the
zone of said cavity, two spaced apart rings projecting from the outer surface of the
bullet, there being a first of the rings which is located at the rear part of the
bullet and a second of the rings located spaced apart from the first ring and towards
the front part of the bullet, the thin wall includes, between both rings, at least
one through orifice.
9. A bullet for an ammunition having a rear part with an open cavity, and a front
part, the cavity is formed by wall portions which are relatively thin regarding the
remaining body of the bullet, the improvement wherein said bullet includes, at the
zone of said cavity, two spaced apart rings projecting from the outer surface of the
bullet, there being a first of the rings which is located at the rear part of the
bullet and a second of the rings located spaced apart from the first ring and towards
the front part of the bullet, the first ring having an outer diameter smaller than
the outer diameter of said second ring.
10. A bullet for an ammunition having a rear part with an open cavity, and a front
part, the cavity is formed by wall portions which are relatively thin regarding the
remaining body of the bullet, the improvement wherein said bullet includes, at the
zone of said cavity, two spaced apart rings projecting from the outer surface of the
bullet, there being a first of the rings which is located at the rear part of the
bullet and a second of the rings located spaced apart from the first ring and towards
the front part of the bullet, the first ring having at least a groove connecting the
opposite sides of the ring.