Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
  • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
  • F42B12/72—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material

Definitions

• This invention relates to a bullet or a projectile for firearms, preferably riflebores, and more specifically to a projectile made of steel, the employment of steel for producing such a projectile and a method for producing said projectile.
• the predominant material used in rifle bore bullets is lead (Pb), most frequently surrounded by a jacket made from copper-zink alloy or from plated steel.
• the jacket functions as a protection for the soft lead core against external deformation, and on the other hand to allow firing at the high muzzle velocities connected with modern firearms. At these velocities, a non-jacketed bullet would deposit lead in the barrel bore due to friction heat.
• the jacket increases the bullets effect upon impact in that it preserves the form of the lead core as the bullet penetrates the game and thereby permits a desired, deep penetration. This later aspect, of course, is of little importance in the field of practise- and contest shooting.
• the jacketed lead bullet is manufactured through several steps.
• Jacket blanks are punched from a jacket plate and formed to a sleeve through two or more form pressing operations.
• the lead core possibly with antimony added to increase the hardness, is draw formed through tapered bores to have the accurate gauge, and cold formed to fit the jacket.
• a joining operation the lead core is fitted within the jacket, whereupon a close fit between core and jacket is of utmost importance, since the occurance of airpockets would cause unbalance with the bullet, resulting in a poor score.
• multiple tools are employed, generally up to six tools, between which the bullets and jackets are moved under the operation, and finally the completed bullets are controlled with respect to e.g. gauge and weight.
• the jacketed lead bullet is available in multiple embodiments, among which the common feature is, that the varied shapings particularly in the sense of jacket construction, are contempla ⁇ ted to increase the effect and penetration ability of the bullet upon game hunting.
• the major part of firearms ammunition is used for practice- and contest shooting, wherein such properties as a fast kill are of no importance.
• some target shooting will take place with the ammunition that later is used for the game hunting, but this particular gallery shooting constitutes merely a minor part of the total amount of rifle ammunition fired in practice- and contest shooting.
• Another object of the present invention will therefore be to provide a small arms projectile, having a shape which contributes to the punching of a cylindrical through hole with a sharp and clean edge upon perforation of the target.
• Fig 1 shows a partially sectioned elevational view of a projec ⁇ tile according to the invention
• Fig 2 shows a target penetrated by a conventional jacketed lead bullet
• Fig 3 shows a target penetrated by a projectile according to the invention
• Fig 4 shows a second embodiment of the inventive projectile.
• Fig 1 shows a projectile or a bullet according to the invention, generally indicated by the reference numeral 1.
• the bullet 1 comprises a torpedo section 2 and a guide section 3.
• the guide section 3 includes circumferentially applied grooves and protruding lands 4, acting to provide a tight seal between bullet and rifle bore and thus preventing the powder combustion gases to pass the bullet.
• the grooves are provided to allow the material of the lands (4) to "escape" when being compressed by the lands of the rifle bore.
• the transition section, between the torpedo section 2 and guide section 3, comprises a shoulder with a slanting front face 5, having an angle ⁇ to the vertical axis 1 within a range of 25- 35°, preferably 30°.
• the guide section 3 further comprises a chamfered rear edge 6.
• the torpedo section 2 is pointed, but the bullet can alternatively be formed with hollow or ogive points or with a flat or a round nose.
• the projectile of the invention is not limited to the design shown in fig 1, but can be given any desired shape to meet the specific requirements of penetration ability or stopping effect.
• the bullet 1 is solid and manufactured from steel of a low carbon (C) content (up to an amount of 0.40 %) and preferably including lead (Pb), which adds to the steel an enhanced cutting capacity (related cutting capacity) rising from the standard machine-steel cutting capacity index 100 (DIN 9SMn23 or SS 1912) to an index 150 for the lead-bearing alloy steel (DIN 9SMnPb28 or BX 1914).
• the high machineability of the lead- bearing alloy steel is utilized for producing, preferably by turning in a lathe, a small arms bullet which has a competitive selling price.
• tellurium (Te) can be added to the steel.
• Tellu ⁇ rium-bearing free-cutting steel has a limited industrial appliance but is used e.g. in tyre studs and is sold by Boxholm, Sweden, under the product symbol 1914-04+Te, and can be obtained with a tellurium additive of 0.02-0.04 %.
• This steel alloy comprises lead to an amount of 0.15-0.35 %.
• the machinabi- lity of the steel is increased, and in the present invention the lubricant effect of the tellurium acting in conjunction with the included lead, is utilized for the production of a bullet with a minimum of lead content, which bullet will not damage the rifle bore upon passage therethrough.
• the high temperature fumes developed under the discharge process presents a more serious threat through erosion of the bore, especially of the conical section, which is exposed to the fumes during the free flight of the bullet, that is before the bullet is completely seated in the bore, than does the friction wear exerted upon the rifle bore by the copper or steel jacketed bullet.
• the bullet 1 is advantageously machined in a lathe and cut off from a bar, which can be of a somewhat smaller diameter than the rifle gauge to permit a coating with an antioxidant compound, such as copper, zinc, nickel or a composi ⁇ tion including one or more of these metals.
• the coating is advantageously applied electro-chemically, but can also be achieved through a common jacket blank.
• the bullet can be completed within three or four steps in an automatic lathe, provided with a bar magazine feed and a tool adapter for several cutters. After machining (and/or after coating) the bullet is gauged, polished by tumbling in fluid, eventually with an addition of abrasive and detergent, whereupon the coating is applied.
• An alternative coating is the application of a layer of polytetrafluoroethylene (PTFE), which will further decrease the friction wear during the passage of the bullet through the bore.
• PTFE polytetrafluoroethylene
• the steel is subjected to normalization to decrease its hardness, e.g. in the case where the bullet is manufactured from cold drawn material.
• this is not considered to be requested in the purpose of decreasing the friction wear of the rifle bore, when a tellurium-bearing steel alloy containing lead is utilized, but can be advantageous when other steel alloys are used or to achieve a certain, desired property of the bullet.
• the bullet of the invention is formed in a roll forming machine, e.g. of a type that is manufactured and sold by Kinefac Corporation, Worcester, Massachusetts, US. These roll forming machines are high perfor ⁇ ming and can produce the inventive bullet at a low unit price.
• the soft steel projectile or bullet of the invention has been subjected to several shooting tests for determination of its performance under various conditions.
• the bullet was machined from steel including a 0.25 percentage of Pb and a 0.04 percentage of Te.
• the bullet was coated with a surrounding Cu-layer of appr. 10 micron.
• the bullet 1 holds a weight of 62 grains (4 g) in caliber 6.5 mm, whereas a jacketed lead bullet of corresponding caliber generally holds a weight of 80 to 160 grains (5 to 10 g), depending on the design and purpose of the bullet.
• test shooting verifies that the inventive bullet of relatively small weight gains a comparatively high muzzle velocity.
• the test record also shows that the bullet 1 at this muzzle velocity obtains good firing groups.
• test shooting was performed outdoors at noon and with a humidity of 40 %. Weather conditions showed a slight cloudiness, light winds to cross wind gusts of 2-8 m/s. The shooting range was 100 m and the muzzle velocities were measured with a Mod. Ml chronograph. The test results were compared to a simultaneously performed Smith Veston laboratory test.
• the soft steel bullet was loaded with a powder charge of 30 grains (appr. 1.95 g) and achieved with this charge an average muzzle velocity of 952.4 m/s in a test series of 10 rounds.
• the factory-loaded jacketed lead bullet used as comparison object had a weight of appr. 93 grains (6 g) and achieved an average muzzle velocity of 926.3 m/s with a charge of 32 grains (appr. 2.1 g), likewise in a test series of 10 rounds.
• the resp. type of bullet was fired in five series of three rounds each.
• the firing groups of the steel bullet then ranged from 17 to 22 mm, and the groups of the jacketed lead bullet ranged from 17 to 25 mm.
• the shoulder of the bullet 1 is given a slanting angle ⁇ to the vertical axis of 30°, which, in respect of the air resistance and the punching efficiency, is considered to be an advantageous chamfer.
• the chamfered rear edge 6 of the guide section 3, which prefe ⁇ rably is rounded or has an angle of chamfer of 45°, is considered to have an advantageous influence on the flight of the bullet by promoting an even bypass of combustion gases when the bullet exits the bore at the rifle muzzle.
• a soft steel bullet of the abovesaid tellurium bearing steel alloy and of the embodiment shown in fig. 4 was used in the .308 W gauge.
• the bullet 1' comprises lands 4' with rounded off edges and an extended, conical guide section 3' with a rounded rear edge 6'.
• This second test was accomplished to determine the bullets performance in conjunction with automatic rifles and machine guns, and the test was performed under varying temperature conditions ranging from -54 to + 52 degrees C. The test shows that the inventive bullet, with respect to automatic fire functions, is not inferior to a reference bullet of conventional type. No deposit material was observed in the barrel bores after shooting.
• the inventive bullet will achieve enhanced charac ⁇ teristics during the discharge process.
• a rifle bullet is not only exposed to high temperature, but also to a gas pressure as high as 3.000 kp/cm 2 or more, which might cause damage to a conventional lead bullet, especially during the free flight.
• this drawback, as well as the drawback of slippage within the rifle bore, will be cleared away.
• the bullet 1 according to the invention is not to be considered as being limited to the embodiments, shown in figs. 1 and 4.
• modifications of the shape of the bullet such as an extended guide section or torpedo section to increase the weight of the bullet or to manipulate the center of gravity, can be accomplis ⁇ hed to impart other ballistic properties to the bullet.
• the torpedo section can be modified to slow the bullet down upon impact within living targets, e.g. by shaping the bullet with a hollow or ogive point or a flat nose.
• the coating in the disclosed embodiments made of copper, could also, as mentioned above, be composed of zink, nickel, a compound containing e.g.
• the polytet- rafluoroethylene coating can be applied in the form of a fully surrounding protective layer or in the form of peripheral rings around the guide section 3, closely fitting within the rifle bore.
• the initially stated purpose is well accomplished by a bullet according to the invention: to provide a bullet, primarely for practice and contest shooting, which significantly reduces the deposition of lead in the environment.
• the addition of lead of the bullet 1 amounts to only somewhat more than 1/400 in comparison with a corresponding conventional bullet.
• Shaping the bullet in accordance with the embodiment of fig. 1 also meets with the second object: providing a bullet primarely for target shooting, which bullet due to its design produces undisputable hit markings.
• composition metals can be utilized to produce a projectile for small arms, such as steels containing alloying ingredients which are used in qualities commonly referred to as free-cutting steels, e.g. silicon (Si), sulphur (S), phosphorus (P) and manganese (Mn), in some cases with the addition of e.g. bismuth (Bi), selenium (Se) or tungsten (W), preferably in combination with lead.
• additives can be utilized to impart specific characteristics to the bullet, such as an increased amount of phosphorus making the bullet brittle and inclined to scatter upon impact, leaving minor or no ricochets, or an addition of tungsten in order to increase the penetration ability.
• the bullet of the invention has been presented as a projectile primarily intended for rifle bores. However, this will not exclude the utilization of the tellurium bearing alloy steel for a projectile intended for smooth barrel guns and for producing round shots.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)
• Powder Metallurgy (AREA)
• Lubricants (AREA)
• Earth Drilling (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

Country Status (8)

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• 1992
  • 1992-06-25 SE SE9201967A patent/SE470389B/sv not_active IP Right Cessation
• 1993
  • 1993-06-23 DE DE69324255T patent/DE69324255T2/de not_active Expired - Fee Related
  • 1993-06-23 EP EP93915073A patent/EP0647308B1/de not_active Expired - Lifetime
  • 1993-06-23 CA CA 2138544 patent/CA2138544A1/en not_active Abandoned
  • 1993-06-23 WO PCT/SE1993/000563 patent/WO1994000730A1/en active IP Right Grant
  • 1993-06-23 ES ES93915073T patent/ES2134851T3/es not_active Expired - Lifetime
  • 1993-06-23 AU AU45192/93A patent/AU4519293A/en not_active Abandoned
• 1994
  • 1994-12-21 FI FI946016A patent/FI110208B/fi not_active IP Right Cessation

Non-Patent Citations (1)

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