Abstract:
A bullet comprises a lead sheet and a zinc foil fixed to the lead sheet, the sheet and foil being rolled and pressure formed into a bullet having generally helical layers of the lead sheet and zinc foil. The bullet exhibits an improved environmental impact on soil, relative to all-lead bullets.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to small arms ammunition, and is directed more particularly to a bullet exhibiting corrosion resistance and, thereby, improved environmental impact on soil. 
     2. Description of the Prior Art 
     Bullets usually are of a dense lead alloy and typically corrode in soil. The release of lead in the environment from the corrosion of bullets is a problem on gun ranges. The organic acids produced by decaying vegetation in the soil react with the lead to produce soluble lead compounds which leach into groundwater. 
     Dense elements, other than lead, have been studied, but each carries a heavy penalty. For example, mercury and uranium are toxic, tungsten and tantalum are very expensive. Iron has been used to replace lead, either partly or wholly, but because of its lesser density does not provide the desired kinetic energy at the point of impact. Further, iron in bullets appears to increase wear in the gun barrel. 
     Accordingly, there exists a need for a bullet having improved environmental impact, relative to lead bullets, but retaining the performance characteristic of lead bullets. 
     SUMMARY OF THE INVENTION 
     An object of the invention is therefore to provide a bullet, and a bullet blank, and more generally, a metal body, having improved environmental impact on soil relative to all-lead bullets and other metal bodies. 
     A further object of the invention is to provide a method for forming a metal body, bullet blank, or bullet, exhibiting improved environmental impact. 
     With the above and other objects in view, a feature of the invention is the provision of a metal body comprising a substrate of lead and a layer of zinc fixed on the lead substrate. 
     In accordance with a further feature of the invention, there is provided a bullet blank comprising a lead sheet and a zinc foil fixed to the lead sheet, the sheet and foil being rolled into a cylindrical configuration. 
     In accordance with another object of the invention, there is provided a bullet comprising a lead sheet and a zinc foil fixed to the lead sheet, the sheet and foil being rolled and pressure formed into a bullet having generally helical layers of the sheet and foil. 
     In accordance with a still further feature of the invention, there is provided a method for forming a metal body, comprising the steps of providing a substrate of lead, fixing a layer of zinc to at least one major surface of the substrate, and forming the substrate and layer into the body. 
     In accordance with a still further feature of the invention, there is provided a method for forming a bullet blank, comprising the steps of providing a lead sheet, fixing a layer of zinc on a major surface of the lead sheet, and rolling the sheet and layer into a cylindrically-shaped configuration. 
     In accordance with still another feature of the invention, there is provided a method for forming a bullet, comprising the steps of providing a lead sheet, fixing at least one layer of zinc on at least one major surface of the lead sheet, rolling the sheet and layer into a cylindrically-shaped configuration to form a bullet blank, and pressing the bullet blank to a bullet configuration. 
     The above and other features of the invention, including various novel details of construction and combinations of parts and method steps, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular devices and methods embodying the invention are shown by way of illustration only and not as limitations of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference is made to the accompanying drawings in which are shown illustrative embodiments of the invention, from which its novel features and advantages will be apparent. 
     In the drawings: 
     FIG. 1 is a sectional view of a lead substrate and zinc coatings fixed thereon; 
     FIG. 2 is a sectional view of the substrate and coatings of FIG. 1 rolled to form a cylindrically-shaped body; 
     FIG. 3 is a perspective view of the body of FIG. 2; and 
     FIG. 4 is a perspective view of a bullet formed from the body of FIG. 3; 
     FIG. 5 is similar to FIG. 4, but illustrative of an alternative embodiment of bullet; and 
     FIG. 6 is similar to FIG. 5, but illustrative of another alternative embodiment of bullet. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, it will be seen that the basis for an improved corrosion-resistant metal body, bullet blank, and bullet, comprises a substrate 10, which may be in sheet form, as shown in FIG. 1, or any other desired form as, for example, spherical, depending upon the desired end use of the body being formed. In the case of bullet blanks and bullets, it is preferable that the substrate 10 be a lead sheet 12. As is well known in the art, pure lead is often too soft for many applications, including bullets. A lead-antimony alloy consisting of lead with a small percentage of antimony is the standard form of lead for bullets and is usually referred to as simply &#34;lead&#34;. As used herein, the term &#34;lead&#34; refers to the lead used in bullets, i.e., lead-antimony alloy. 
     Fixed to at least one major surface 14 of the lead sheet 12 is a zinc layer or covering 16, which may be in the form of a zinc foil 18, preferably fused to the lead sheet 12. Preferably fixed to a second major surface 20 of the lead sheet 12 is a second zinc layer or covering 22, which may be in the form of a second zinc foil 24, and may be fused to the sheet second major surface 20. The zinc layers 16, 22 may also be in the form of a coating applied to the sheet 12. 
     Referring to FIGS. 2 and 3, it will be seen that the lead sheet and zinc layer composite sheet 26 is rolled into a generally cylindrically-shaped form, constituting a bullet blank 28. The bullet blank 28 accordingly has generally spiral or helical layers of lead sheet 12 and zinc layers 16. 
     The bullet blank 28 is subjected to a pressing operation to produce a bullet 30. The bullet 30, compared to the usual alllead prior art bullet, reduces the amount of lead released as the spent bullet weathers and corrodes. Further, if the bullet fragments, pieces of lead are accompanied by pieces of the zinc covering. Still further, the small amount of zinc used in the foils 18, 24 does not significantly reduce the overall density of the bullet. Zinc is considered an essential mineral for health and is not generally considered a toxic element. Zinc corrodes slowly, and when a hole does corrode through the zinc covering 16 and/or 22, the zinc acts as a sacrificial metal and reduces the rate of corrosion of the lead. 
     Many modern high-speed bullets require a relatively hard material on the outer surface, particularly where the bullet contacts the rifling in a barrel. In FIGS. 5 and 6, there are shown alternative embodiments in which the bullet 30 of FIG. 4 is covered with a full length jacket 40 (FIG. 5) of copper or brass or a partial-jacket 42 (FIG. 6) of copper or brass. 
     It is to be understood that the present invention is by no means limited to the particular construction herein disclosed and/or shown in the drawings, but also comprises any modifications or equivalents within the scope of the disclosure. For example, while the above description and the drawings relate primarily to formation of a bullet blank and bullet, and while the invention is expected to find utility in that area, it will be apparent that the invention readily is applicable to metal bodies generally, where concern for lead solubility poses a problem, such as in lead weights for ship ballast, lead shielding for radiation protection, and lead shot at skeet and trap ranges. 
     There is thus provided a bullet blank and bullet and, more generally, a metal body, exhibiting improved environmental qualities over similar items of substantially wholly lead structure.