Polymer coated lead-free bullet

Abstract

A method of making a polymer-coated, lead-free projectile. In an embodiment, the method comprises compressing a lead-free metal powder to form a green core, heating the green core to bond the lead-free metal powder to form a metal compact of desired strength and placing the metal compact into fluidized bed of polymer to bond polymer to the metal compact to form a polymer coated compact. A polymer-coated, lead-free projectile made according to the described method, and a loaded round comprising the polymer-coated, lead-free projectile are also disclosed.

What is claimed is: 
     
         1 . A method of making a polymer-coated, lead-free projectile, said method comprising:
 compressing a lead-free metal powder to form a green core having a density ranging from 6.0-7.6 g/cc;   heating the green core to bond the lead-free metal powder to form a metal compact of desired strength; and   placing the metal compact that is at an elevated temperature into fluidized bed of polymer to bond said polymer to the metal compact to form a polymer coated, lead-free projectile,   wherein the polymer has a glass transition temperature of at least 250 degrees Fahrenheit.   
     
     
         2 . The method of  claim 1 , wherein heating is performed at a temperature ranging from 1000-2000 degrees Fahrenheit. 
     
     
         3 . The method of  claim 1 , wherein the lead-free metal powder comprises iron, copper, zinc, tungsten, bismuth, nickel, tin, boron, tungsten and/or alloys thereof, and/or oxides thereof. 
     
     
         4 . The method of  claim 3 , wherein the lead-free metal powder comprises iron. 
     
     
         5 . The method of  claim 1 , wherein the polymer comprises Polyamide (PA), Polyimide (PI), Polyphenylene Sulfide (PPS), Polyetherimide (PEI), Polyetherketone (PEK), Polyetheretherketone (PEEK), Polyetherketoneketone (PEKK), Polysulfone (PSU), Polyetheretherketoneketone (PEEKK). 
     
     
         6 . The method of  claim 5 , wherein the polymer comprises Polyamide (PA), Polyetheretherketone (PEEK), or Polyetherketoneketone (PEKK). 
     
     
         7 . The method of  claim 6 , wherein the Polyamide (PA) is nylon-11. 
     
     
         8 . The method of  claim 1 , wherein the lead-free metal powder comprises iron and the compact exhibits a density ranging from 6.5 to 7.0 g/cc. 
     
     
         9 . The method of  claim 1 , wherein said elevated temperature is above 200 degrees Fahrenheit. 
     
     
         10 . The method of  claim 1 , further comprising at least one step to introduce into the polymer-coated, lead-free projectile at least one design chosen from a cannelure groove, a tipped point, a hollow point, boat-tail, ring, a grove, and combinations thereof. 
     
     
         11 . The method of  claim 1 , further comprising at least one post processing step to size the polymer-coated, lead-free projectile to achieve a desired diameter. 
     
     
         12 . The method of  claim 1 , wherein the projectile comprises a frangible metal bullet. 
     
     
         13 . The method of  claim 1 , further comprising loading the polymer-coated, lead-free projectile into a cartridge. 
     
     
         14 . The method of  claim 1 , wherein the metal compact is placed in the fluidized bed of polymer to form a polymer coating having a thickness ranging from 0.001 to 0.030 inches. 
     
     
         15 . The method of  claim 14 , wherein the polymer coating has a thickness ranging from 0.005 to 0.010 inches. 
     
     
         16 . A polymer-coated, lead-free projectile made according to the method according to  claim 1 . 
     
     
         17 . The polymer coated, lead free projectile of  claim 16 , wherein the projectile is bullet made of a iron and coated with a polymer coating made of Polyamide (PA), Polyetheretherketone (PEEK), or Polyetherketoneketone (PEKK), and having a thickness ranging from 0.005 to 0.010 inches. 
     
     
         18 . A cartridge comprising:
 a metal cartridge case;   a primer;   a propellant within said cartridge case;   a polymer-coated, lead-free projectile according to  claim 16 .   
     
     
         19 . The cartridge of  claim 18 , wherein said cartridge is a rimfire cartridge or a centerfire cartridge. 
     
     
         20 . The cartridge of  claim 18 , wherein cartridge is a rifle cartridge, or a pistol bullet/cartridge.