Ammunition and explosives – Cartridges – Projectile structure
Reexamination Certificate
1998-01-16
2001-04-03
Tudor, Harold J. (Department: 3641)
Ammunition and explosives
Cartridges
Projectile structure
C102S501000, C102S511000, C102S514000, C029S002100, C086S001100
Reexamination Certificate
active
06209459
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns a method for marking a bullet with characters and bullets marked according to the method.
BACKGROUND OF THE INVENTION
Ammunition bullets are characterized by, among other things, caliber and weight. Caliber represents the diameter of the bullet, while weight represents the mass of the bullet. Bullet mass is commonly designated in terms of avoirdupois grain weight throughout the United States.
The flight trajectory and terminal performance of a bullet depend heavily upon the caliber and the weight of the bullet. For example, with other ballistic variables being equivalent, a bullet with a heavier weight sustains its flight velocity better than a lighter weight bullet. The heavy weight bullet, usually launched at a lower initial velocity, drops further from the line of sight than a lighter bullet when fired at the same target. This requires aiming adjustments by the shooter when using ammunition with different weight bullets.
Heavy weight bullets typically penetrate deeper upon terminal impact than lighter bullets, which partially compensates for their lower velocities. Other technical advantages and disadvantages of light or heavy bullets are well known to experienced marksmen.
Marksmen therefore want to know the weight of the bullets in the cartridges they intend to shoot. Differences in bullet weights often are not apparent simply by viewing or handling loaded cartridges. Bullets weights for a common cartridge in its various loadings might vary between 100 and 125 grains. A 25 grain (0.057 ounce) difference is not substantial enough to allow the shooter to quickly or reliably differentiate between two cartridges while holding one of each bullet weight type. Visual determination of bullet weight is not practical because a significant portion of a bullet in a cartridge is obscured by the cartridge casing. Other important bullet characteristics such as construction materials and design features also may not be visibly apparent after the bullet is assembled into a finished cartridge.
Most manufacturers mark ammunition packaging with some indication of bullet weight and perhaps other bullet characteristics. However, packaging markings are ineffective once the bullet has been removed from the package. Moreover, spent casings of cartridges often are reloaded with new cartridge components and the resulting reloads do not necessarily incorporate the proper information to identify the bullet loaded therein.
Some inventions are known whereby bullets convey information. Marking bullets with a system of bands or grooves to indicate bullet characteristics is described in, for example, U.S. Pat. Nos. 1,632,156 and 1,650,908. But, in each situation these marking schemes require marksmen to memorize several different configurations of bands and the corresponding bullet characteristics. Further, such marking systems are not generally known by the shooting public.
U.S. Pat. Nos. 1,887,324, 4,150,624 and 5,485,789 describe bullets having identifiers embedded therein. These inventions offer no help to marksmen because the information is stored inside the bullet and is not visible. Such information generally is of a type not intended for marksmen anyway as such information is usually provided for forensic purposes.
SUMMARY OF THE INVENTION
Based on the above, it is apparent that a need exists for a method for marking bullets so that marksmen can quickly and reliably identify the bullet weight and type when loaded in a cartridge. The present invention addresses this need.
One embodiment of the present method for etching a character or characters onto a bullet comprises first providing a bullet having a coating on at least a portion thereof. The coating typically has a surface appearance that contrasts with a portion of the bullet that underlies the coating. One or more characters are then etched through the coating. For example, a character or characters may be etched through the coating to reveal the underlying bullet substratum.
The etching step can be performed mechanically, chemically or with a localized energy source such as an electron beam or a laser. Examples of lasers having sufficient power for commercial production of large quantities of etched bullets according to the present method include, without limitation, YAG and CO
2
lasers. Alternatively, the etching step can be performed mechanically, such as by applying an abrasive to the coating, or by stamping a dot matrix pattern through the coating to form a character or characters.
Functionally, the coating acts as a contrast agent, but it also can have other desired technical functions when applied to a bullet, such as acting as a lubricant. Coatings currently considered useful for practicing the present method are selected from the group consisting of molybdenum disulfide, tin, copper, metallic oxides, zinc, nickel, silicon, organic resins, paints, stains, aluminum, gold, silver, and mixtures and alloys thereof. Molybdenum disulfide is a currently preferred coating.
The present invention is particularly useful for etching bullet weight and type numerals onto a bullet. The method involves providing a cartridge comprising a bullet and a casing. The outer surface of the bullet is then coated with molybdenum disulfide. A laser is then focused on the coating in a desired pattern to remove a portion of the coating corresponding to the pattern. Contrast between the coating and the exposed substratum of the bullet helps marksmen see the bullet weight and type characters. These characters are located on the bullet in a position that they are easily seen even after the bullet is loaded in the cartridge casing.
The present invention also is directed to bullets etched by the method briefly described above. One embodiment of an etched bullet comprises a core and an jacket. A coating is applied over at least a portion of the plating, and characters are etched through the coating to reveal an outer surface of the plating.
REFERENCES:
patent: 1275669 (1918-08-01), Forbes
patent: 1632156 (1927-06-01), Wiley
patent: 1650908 (1927-11-01), Ramsey
patent: 1678162 (1928-07-01), Pedusen
patent: 1887324 (1932-11-01), Pocoroba
patent: 4150624 (1979-04-01), Hammond
patent: 4454175 (1984-06-01), Martin
patent: 5400716 (1995-03-01), Mayer
patent: 5485789 (1996-01-01), Collier
patent: 5528990 (1996-06-01), Corzine et al.
patent: 5698816 (1997-12-01), Rexby
patent: 499832 (1992-08-01), None
patent: 16922 (1905-05-01), None
Alexander Kenneth L.
Conley Dennis K.
Hill Jerry L.
Kaufman Francis J.
Moore Steven R.
Blount, Inc.
Klarquist Sparkman Campbell & Leigh & Whinston, LLP
Tudor Harold J.
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