ROTATIONALLY SYMMETRICAL LEAD MACHINE-TOOL TURNED PROJECTILE FOR GAS-GUNS

Abstract

A rotationally symmetrical lead metal-cut projectile of the caliber ranging from .17 to .50 for gas-guns comprises at least 60% by weight of lead, up to 40% by weight of tin and up to 5% by weight of admixtures selected from the following list: Ag, As, Bi, Cd, Cu, Fe, Ni, Sb, Zn, Ti or their mixtures thereof.

Claims

1. A method of manufacture of a rotationally symmetrical lead metal-cut projectile comprising at least 60% by weight of lead, up to 40% by weight of tin and up to 5% by weight of admixtures selected from a group consisting of Ag, As, Bi, Cd, Cu, Fe, Ni, Sb, Zn, Ti and mixtures thereof, wherein the projectile caliber is ranging from .17 to .50, the method comprising: clamping a bar made of lead alloy comprising at least 60% by weight of lead into a collet on a mandrel of a machine-tool; clamping a cutter and a cut-off tool on a cutter support of the machine-tool; programming in the machine-tool a metal-cutting curve; starting the machine-tool is starting; machining the bar made of lead alloy by the cutter as per the metal-cutting curve; and separating a machined projectile in a point of the flat back by the cut-off tool.

2. The method of manufacture of the rotationally symmetrical lead metal-cut projectile according to claim 1, wherein the cutter or the cut-off tool is equipped with a blade made of carbide or a blade made of high-speed steel of CSN class 19.

3. The method of manufacture of the rotationally symmetrical lead metal-cut projectile according to claim 1, wherein the bar is rotating around its central axis and the cutter is moving in one plane, wherein the central axis is a part of this plane.

4. The method of manufacture of the rotationally symmetrical lead metal-cut projectile according to claim 1, wherein the cut-off tool blade thickness ranges between 0.4 and 1.5 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1A: A lead turned projectile 1 according to Example 1 with two grooves is presented. The turned projectile 1 has a flat back 2, where diameter of flat back 2 is smaller than diameter of centre 3 of the projectile 1. The projectile 1 has a rounded face 4. A central axis 5 of the projectile 1 is showed.

[0042] FIG. 1B: Measurement of diameters of the projectiles according to Example 1A. The graph shows the variance of the measurements of the individual turned projectiles machined.

[0043] FIG. 1C: Number of target hits of a series of shots according to Example 1B. There is a clear comparation between lead turned projectiles according to this invention and projectiles from the state of the art.

[0044] FIG. 2: A lead turned projectile 1 according to Example 2A of a bent type with a pointed face 4 and flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0045] FIG. 2B: Measurement of diameters of the projectiles according to Example 2A. The graph shows the variance of the measurements of the individual turned projectiles machined.

[0046] FIG. 3A: A lead turned projectile 1 according to Example 3A, of a round type with a pointed face 4 and a flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0047] FIG. 3B: Measurement of diameters of the projectiles according to Example 3A. The graph shows the variance of the measurements of the individual turned projectiles machined.

[0048] FIG. 3C: Number of target hits of 10 shots according to Example 3B. There is a clear comparation between lead turned projectiles according to this invention and projectiles from the state of the art.

[0049] FIG. 4: A lead turned projectile 1 according to Example 4, 5, and 6 with three grooves, with a rounded face 4 and a flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0050] FIG. 5A: A lead turned projectile 1 according to Example 7A, with three grooves, with a rounded face 4 and a flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0051] FIG. 5B: A lead turned projectile according to Example 7B, without grooves, with a pointed face 4 and a flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0052] FIG. 5C: A lead turned projectile according to Example 7C, without grooves, with a pointed face 4 and a flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0053] FIG. 5D: A lead turned projectile according to Example 7D, with three grooves, with a depression on a face 4 and a flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0054] FIG. 5E: A lead turned projectile according to Example 7E, without grooves, with a depression on a face 4 and a flat back 2, where diameter of flat back 2 is smaller than diameter of a centre 3 of the projectile 1.

[0055] FIG. 5F: A lead turned projectile according to Example 7F, without, with a rounded face 4 and a flat back 2.

EXAMPLES OF INVENTION EXECUTION

Example 1A

[0056] A total of 28 rotationally metal-cut projectiles of the caliber .22, i.e. 5.5 mm, for gas-guns were manufactured with the standard deviation of diameter ±0.005 mm, with the length 9.4 mm, with the standard deviation of length ±0.02 mm, with the weight per projectile 2.02 g, with the standard deviation of weight ±0.0015 g.

[0057] A bar with the length of 300 mm and with the diameter of 6 mm made of lead alloy comprising 99.8% by weight of lead and 0.2% by weight of antimony was clamped into a collet on the mandrel of the CNC machine. The CNC machine was adjusted as follows: the revolutions of the mandrel were set at 2,200 revolutions per minute and the advance movement of metal-cutting was 170 mm/min. The metal-cutting process was programmed based on the curve provided in FIG. 1A.

[0058] A cutter with a carbide plate and a cut-off blade made of high-speed steel with the blade thickness of 0.8 mm were fixed to the cutter support on the CNC machine. Then the CNC machine was started and the bar began to be metal-cut along the set path of the cutter, and/or the required shape of the projectile. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool. The projectile was then removed from the metal-cutting space and the process was repeated for the following projectile: the bar clamped in the CNC machine was moved forward by the length of the separated metal-cut projectile and the metal-cutting of the bar repeated with the next projectile.

[0059] A total of 28 lead rotationally metal-cut projectiles were manufactured from the bar with the length of 300 mm. All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.09% of diameter, were included in the compliant series. Projectiles whose measured deviations were higher, were discarded. In this specific production run, none projectile was discarded, which means that 28 projectiles were included in the series. The measurement is provided in FIG. 1B.

Example 1B

[0060] Use of the Projectile According to Example 1A

[0061] The projectiles according to Example 1A were used for firing at a distance of 205 m, where lead projectiles pressed according to the state of the art, Airgun Slugs Nielsen cal. 5.5 mm, weight 27.5 grain, which corresponds 1.78 g and lead projectiles according to the present invention were compared. To compare the projectiles, one shooter with the same gas-operated weapon, the same target, the same distance and identical weather conditions were ensured. The target has a circular profile with the diameter of 6 cm; two series of five shots, i.e. 2×5 shots, were fired. The lead metal-cut projectiles as per Example 1A in the first series achieved 5 hits out of 5 shots, i.e. 100%, while in the second series it was 4 hits out of 5 shots, i.e. 80%. The tested pressed projectiles according to the state of the art in the first series achieved 2 hits out of 5 shots, i.e. 40%, and in the second series it was again 2 hits out of 5 shots, i.e. 40% as well.

[0062] A significant benefit of the lead metal-cut projectiles was in particular the considerably higher measured value of ballistic coefficient BC=0.149. The manufacturer of the pressed projectiles according to the state of the art provides BC=0.079. The significantly higher value of ballistic coefficient of the metal-cut projectiles ensured nearly half the value of side deviation with the same acting force of side wind.

[0063] Another advantage of the metal-cut projectiles compared to the pressed ones was their weight and dimensional stability. It ensured the very low standard deviation of the lead metal-cut muzzle speed being ±0.2 m/s, which caused a height deviation of ±0.44 cm from the aiming point on the target. The used pressed projectiles according to the state of the art attained the standard deviation of muzzle speed ±0.9 m/s, which caused a difference in height on the target ±2.15 cm from the aiming point. Both projectiles were fired at the same speed of 279 m/s.

[0064] The lead rotationally metal-cut projectiles thus provided the shooter with a greater shooting error without missing the target compared to the pressed lead projectiles whose parameters provided practically no space for the shooter's error resulting in missing the target.

Example 2A

[0065] A total of 14 rotationally metal-cut projectiles of the caliber .22, i.e. 5.5 mm, for gas-guns were manufactured with the standard deviation of diameter ±0.005 mm, with the length 20.2 mm, with the standard deviation of length ±0.02 mm, with the weight per projectile 4.02 g, with the standard deviation of weight ±0.0018 g.

[0066] Following manufacture, a bar with the length of 300 mm and with the diameter of 6 mm made of lead alloy comprising 99.96% by weight of lead and 0.04% by weight of non-specified admixtures was clamped into a collet on the mandrel of the CNC machine. The CNC machine was adjusted as follows: the revolutions of the mandrel were set at 2,200 revolutions per minute and the advance movement of metal-cutting was 170 mm/min. The metal-cutting process was programmed based on the curve provided in FIG. 2A.

[0067] A cutter with a carbide plate and a cut-off blade made of high-speed steel with the blade thickness of 0.8 mm were fixed to the cutter support on the CNC machine. Then the CNC machine was started and the bar began to be metal-cut along the set path of the cutter, and/or the required shape of the projectile. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool. The projectile was then removed from the metal-cutting space and the process was repeated for the following projectile: the bar clamped in the CNC machine was moved forward by the length of the separated metal-cut projectile and the metal-cutting of the bar repeated with the next projectile.

[0068] A total of 14 lead projectiles were manufactured from the bar with the length of 300 mm. All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.09% of diameter, were included in the compliant series. Projectiles whose measured deviations were higher, were discarded. In this specific production run, none projectile was discarded, which means that 14 projectiles were included in the series. The measurement is provided in FIG. 2B.

Example 2B

[0069] Use of the Projectile According to Example 2A—the World Record

[0070] The projectiles according to Example 2A were used for firing at a distance of 1,280 m, where lead projectiles pressed according to the state of the art, Airgun Slugs H&N, cal. 5.5 mm, weight 30 grain, which correspond 1.94 g and lead rotationally metal-cut projectiles according to the present invention were compared. To compare the projectiles, one shooter with the same gas-operated weapon, the same target, the same distance and identical weather conditions were ensured. The target had the shape of a rectangle with the size of 56×46 cm; a total of 6 shots were fired. The lead metal-cut projectiles according to Example 2A allowed the said target to be hit at this distance by the sixth shot, i.e. by 1 shot out of 6. The tested pressed projectiles do not achieve satisfactory ballistic parameters allowing the target to be hit at this distance—it is not physically possible to take aim as the drop of projectiles is out of the scope of the projectile aiming system.

[0071] A significant benefit of the lead metal-cut bullets was in particular the considerably higher measured value of ballistic coefficient BC=0.266. The lead pressed projectiles according to the state of the art only achieved the value of the ballistic coefficient BC=0.079. The significantly higher ballistic coefficient of the lead metal-cut projectiles ensured nearly 3.5 times lower side deviation with the same acting force of side wind. In addition, lead metal-cut projectiles have a significantly lower drop in muzzle speed during motion, by which the ballistic curve is improved—flattened.

[0072] Another advantage of the metal-cut projectiles compared to pressed ones was the weight and dimensional stability which ensured a very low measured standard deviation of the projectile muzzle ±0.3 m/s, that resulted in a height deviation from the aiming point of only 5 cm.

Example 3A

[0073] A total of 17 rotationally metal-cut projectiles of the caliber .22, i.e. 5.5 mm, for gas-guns were manufactured with the standard deviation of diameter ±0.005 mm, with the length 16.7 mm, with the standard deviation of length ±0.02 mm, with the weight per projectile 3.13 g, with the standard deviation of weight ±0.0017 g.

[0074] A bar with the length of 300 mm and with the diameter of 6 mm made of lead alloy comprising 95% by weight of lead and 5% by weight of antimony was clamped into a collet on the mandrel of the NC machine. The NC machine was adjusted as follows: the revolutions of the mandrel were set at 1800 revolutions per minute and the advance movement of metal-cutting was 110 mm/min. The metal-cutting process was programmed based on the curve provided in FIG. 3.

[0075] A cutter with a carbide plate and a cut-off blade made of carbide with the blade thickness of 0.6 mm were fixed to the cutter support on the CNC machine. Then the CNC machine was started and the bar began to be metal-cut along the set path of the cutter, and/or the required shape of the projectile. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool. The projectile was then removed from the metal-cutting space and the process was repeated for the following projectile: the bar clamped in the CNC machine was moved forward by the length of the separated metal-cut projectile and the metal-cutting of the bar repeated with the next projectile.

[0076] A total of 17 lead projectiles were manufactured from the bar with the length of 300 mm. All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.09% of diameter, were included in the compliant series. Projectiles whose measured deviations were higher, were discarded. In this specific production run, none projectile was discarded, which means that all of the 17 projectiles were included in the series. The measurement is provided in FIG. 3B.

Example 3B

[0077] Use of the Projectile According to Example 3A

[0078] The projectiles according to Example 3A were used for firing at a distance of 505 m, where lead projectiles pressed according to the state of the art, JSB KnockOut Slugs cal. 5.5 mm, weight 25.5 grains, which correspond 1.65 g and lead projectiles according to the present invention were compared. To compare the projectiles, one shooter with the same gas-operated weapon, the same target, the same distance and identical weather conditions were ensured. The target had the shape of a rectangle with the dimensions of 25×25 cm; a total of 10 shots were fired. The lead metal-cut projectiles as per Example 3A achieved 5 hits out of 10, i.e. 50% success rate. The tested pressed projectiles according to the state of the art achieved 1 hit out of 10, i.e. 10% success rate, which was rather coincidence than reproducible precision.

[0079] A significant benefit of the lead metal-cut bullets was in particular the considerably higher measured value of ballistic coefficient BC=0.22. The attained value of ballistic coefficient of the pressed projectiles was only BC=0.079. This means that the lead metal-cut projectiles ensured nearly 2.8 times lower side deviation with the same acting force of side wind.

[0080] Another advantage of the metal-cut projectiles compared to pressed ones was the weight and dimensional stability which ensured a very low measured standard deviation of the projectile muzzle ±0.3 m/s, that resulted in a height deviation from the aiming point of only ±4.94 cm on the target at a distance of 505 m. The employed pressed projectiles attained the standard deviation of muzzle speed ±0.9 m/s, which caused a difference in height on the target ±24.5 cm from the aiming point, which means that it was necessary to aim at the target that vertical size of which was at least 50 cm, i.e. twice the size, to allow its hitting by each shot in the ideal theoretical case (with no error of the shooter and with no effect of wind and other variables). Both types of projectile were fired at the same speed of 272 m/s.

[0081] The lead metal-cut projectiles thus provided the shooter with the possibility of theoretical hit by all shots unlike in the case of the lead pressed projectiles the parameters of which failed to provide even a theoretical possibility of hitting by all shots. Using common statistics and prediction, the probability of absolute missing the target was higher, if light wind was taken into account.

Example 4A

[0082] A total of 30 rotationally metal-cut projectiles of the caliber .17, i.e. 4.32 mm, for gas-guns were manufactured with the standard deviation of diameter ±0.005 mm, with the length 8.3 mm, with the standard deviation of length ±0.02 mm, with the weight per projectile 1.11 g, with the standard deviation of weight ±0.0012 g.

[0083] A bar with the length of 300 mm and with the diameter of 5 mm made of lead alloy comprising 98.5% by weight of lead and 1.5% by weight of cadmium was clamped into a collet on the mandrel of the CNC machine. The CNC machine was adjusted as follows: the revolutions of the mandrel were set at 1,200 revolutions per minute and the advance movement of metal-cutting was 90 mm/min. The metal-cutting process was programmed based on the curve provided in FIG. 4.

[0084] A cutter with a carbide plate and a cut-off blade made of high-speed steel with the blade thickness of 1 mm were fixed to the cutter support on the CNC machine. Then the CNC machine was started and the bar began to be metal-cut along the set path of the cutter, and/or the required shape of the projectile. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool. The projectile was then removed from the metal-cutting space and the process was repeated for the following projectile: the bar clamped in the CNC machine was moved forward by the length of the separated metal-cut projectile and the metal-cutting of the bar repeated with the next projectile.

[0085] A total of 30 lead projectiles were manufactured from the bar with the length of 300 mm. All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.11% of diameter, were included in the compliant series. Projectiles whose measured deviations were higher, were discarded. In this specific production run, none projectile was discarded, which means that all of the 30 projectiles were included in the series.

Example 4B

[0086] Use of the Projectile According to Example 4A

[0087] The projectiles as per Example 4A were used for shooting at a distance of 205 m. The target had a circular profile with the diameter of 6 cm and one series of five shots was fired. The lead metal-cut projectiles as per Example 4A achieved 3 hits out of 5 shots. The achieved results could not be compared as projectiles for gas-operated guns/rifles with this caliber are not available.

Example 5

[0088] A total of 18 rotationally metal-cut projectiles of the caliber .30, i.e. 7.62 mm, for gas-guns were manufactured with the standard deviation of diameter ±0.005 mm, with the length 14.6 mm, with the standard deviation of length ±0.02 mm, with the weight per projectile 6.05 g, with the standard deviation of weight ±0.0035 g.

[0089] A bar with the length of 300 mm and with the diameter of 8 mm made of lead alloy comprising 98.5% by weight of lead and 1.5% by weight of copper was clamped into a collet on the mandrel of the NC machine. The NC machine was adjusted as follows: the revolutions of the mandrel were set at 2600 revolutions per minute and the advance movement of metal-cutting was 200 mm/min. The metal-cutting process was programmed based on the curve provided in FIG. 4.

[0090] A cutter with a carbide plate and a cut-off blade made of high-speed steel with the blade thickness of 0.8 mm were fixed to the cutter support on the CNC machine. Then the CNC machine was started and the bar began to be metal-cut along the set path of the cutter, and/or the required shape of the projectile. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool. The projectile was then removed from the metal-cutting space and the process was repeated for the following projectile: the bar clamped in the CNC machine was moved forward by the length of the separated metal-cut projectile and the metal-cutting of the bar repeated with the next projectile.

[0091] A total of 18 lead projectiles were manufactured from the bar with the length of 300 mm. All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.065% of diameter, were included in the compliant series. Projectiles whose measured deviations were higher, were discarded. In this specific production run, none projectile was discarded, which means that all of the 18 projectiles were included in the series.

Example 6

[0092] A total of 15 rotationally metal-cut projectiles of the caliber .35, i.e. 9 mm, for gas-guns were manufactured with the standard deviation of diameter ±0.005 mm, with the length 17.3 mm, with the standard deviation of length ±0.02 mm, with the weight per projectile 10 g, with the standard deviation of weight ±0.0071 g.

[0093] A bar with the length of 300 mm and with the diameter of 10 mm made of lead alloy comprising 95% by weight of lead, 2.5% by weight of silver, and 2.5% by weight of nickel was clamped into a collet on the mandrel of the CNC machine. The CNC machine was adjusted as follows: the revolutions of the mandrel were set at 1,500 revolutions per minute and the advance movement of metal-cutting was 120 mm/min. The metal-cutting process was programmed based on the curve provided in FIG. 4.

[0094] A cutter with a carbide plate and a cut-off blade made of high-speed steel with the blade thickness of 1.5 mm were fixed to the cutter support on the CNC machine. Then the CNC machine was started and the bar began to be metal-cut along the set path of the cutter, and/or the required shape of the projectile. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool. The projectile was then removed from the metal-cutting space and the process was repeated for the following projectile: the bar clamped in the CNC machine was moved forward by the length of the separated metal-cut projectile and the metal-cutting of the bar repeated with the next projectile.

[0095] A total of 15 lead projectiles were manufactured from the bar with the length of 300 mm. All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.055% of diameter, were included in the compliant series. Projectiles whose measured deviations were higher, were discarded. In this specific production run, one projectile was discarded, which means that 14 projectiles were included in the series.

Example 7A

[0096] A total of 8 lead rotationally metal-cut projectiles of the caliber of .35, i.e. 9 mm designed for gas-guns, with the length of 30.3 mm were manufactured.

[0097] A bar with the length of 300 mm and with the diameter of 10 mm made of lead alloy comprising 60% by weight of lead and 40% by weight of tin was clamped into a collet on the mandrel of the CNC machine and processed in two steps with the constant position of the bar along the curve provided in FIG. 5A. In step one, material was removed from the bar by the cutter to roughly form the required shape of the projectile—with tiny steps created on the bar. In step two, the rough shape of the projectile was finished to have the required shape of the projectile. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool, removed from the metal-cutting space and the process was repeated for the following projectile again in the position of the rotating bar in two steps.

[0098] All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.055% of diameter, were included in the compliant series.

Example 7B

[0099] A total of 10 lead rotationally metal-cut projectiles of the caliber of .17, i.e. 4.5 mm designed for gas-guns, with the length of 19 mm were manufactured.

[0100] A bar with the length of 300 mm and with the diameter of 5 mm made of lead alloy comprising 95% by weight of lead and 5% by weight of tin was clamped into a collet on the mandrel of the CNC machine and processed with the constant position of the bar along the curve provided in FIG. 5B. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool, removed from the metal-cutting space and the process was repeated for the following projectile again in the position of the bar.

[0101] All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.11% of diameter, were included in the compliant series.

Example 7C

[0102] A total of 10 lead rotationally metal-cut projectiles of the caliber of .50, i.e. 12.7 mm designed for gas-guns, with the length of 28.7 mm were manufactured.

[0103] A bar with the length of 300 mm and with the diameter of 13 mm made of lead alloy comprising 95% by weight of lead, 3% by weight of tin, and 2% by weight of antimony was clamped into a collet on the mandrel of the CNC machine and processed with the constant position of the rotating bar along the curve provided in FIG. 5C. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool, removed from the metal-cutting space and the process was repeated for the following projectile again in the position of the rotating bar.

[0104] All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.039% of diameter, were included in the compliant series.

Example 7D

[0105] A total of 10 lead rotationally metal-cut projectiles of the caliber of .17, i.e. 4.32 mm designed for gas-guns, with the length of 8 mm were manufactured.

[0106] A bar with the length of 300 mm and with the diameter of 5 mm made of lead alloy comprising 97% by weight of lead, 0.8% by weight of astatine, and 2.2% by weight of bismuth was clamped into a collet on the mandrel of the CNC machine and processed on the outer side with the constant position of the rotating bar along the curve provided in FIG. 5D. After the projectile was metal-cut, the projectile was directly in the CNC machine finalized from the front side by boring using a taper caliber fixed on the cutter support. After the first projectile was calibered, the projectile was separated from the bar by the cut-off tool, removed from the metal-cutting space and the process was repeated for the following projectile.

[0107] All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.11% of diameter, were included in the compliant series.

Example 7E

[0108] A total of 10 lead rotationally metal-cut projectiles of the caliber of .22, i.e. 5.5 mm designed for gas-guns, with the length of 23 mm were manufactured.

[0109] A bar with the length of 300 mm and with the diameter of 6 mm made of lead alloy comprising 99% by weight of lead, 0.4% by weight of iron, and 0.6% by weight of zinc was clamped into a collet on the mandrel of the CNC machine and processed on the outer side with the constant position of the rotating bar along the curve provided in FIG. 5E. After the projectile was metal-cut, the projectile was directly in the CNC machine finalized from the front side by boring using a cylindrical caliber. After the first projectile was calibered, the projectile was separated from the bar by the cut-off tool, removed from the metal-cutting space and the process was repeated for the following projectile.

[0110] All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.09% of diameter, were included in the compliant series.

Example 7F

[0111] A total of 10 lead rotationally metal-cut projectiles of the caliber of .26, i.e. 6.5 mm designed for gas-guns, with the length of 6.6 mm were manufactured.

[0112] A bar with the length of 300 mm and with the diameter of 7 mm made of lead alloy comprising 99.5% by weight of lead and 0.5% by weight of titanium was clamped into a collet on the mandrel of the CNC machine and processed with the constant position of the rotating bar along the curve provided in FIG. 5E. After the first projectile was metal-cut, the projectile was separated from the bar by the cut-off tool, removed from the metal-cutting space and the process was repeated for the following projectile again in the position of the rotating bar.

[0113] All projectiles were automatically measured with a measuring tool with the accuracy of 2 μm. All projectiles that were manufactured with the required tolerance ±0.005 mm, i.e. ±0.076% of diameter, were included in the compliant series.

LIST OF MARKS FOR TERMS

[0114] 1. projectile [0115] 2. back of the projectile 1 [0116] 3. centre of the projectile 1 [0117] 4. face of the projectile 1 [0118] 5. central axis of the projectile 1

APPLICABILITY IN INDUSTRY

[0119] The lead metal-cut projectiles designed for gas-guns with a higher precision and a higher value of ballistic coefficient compared to pressed or cast projectiles.