Lead-free ammunition projectile
A bullet (ammunition projectile) comprising a branched condensation polymer and a filler, wherein the filler is present in an amount from about 10% to 65% by volume of the branched condensation polymer and filler is described. The bullet may be made by heating a mixture comprised of a branched condensation polymer and a filler comprised of a first and second filler having differing densities and differing particle size distribution to form a molten mixture and injecting the molten mixture into a mold to form the ammunition projectile allowing for the tailoring of the characteristics of the bullet for differing applications.
1 . An ammunition projectile comprising:
a branched condensation polymer, and
a filler, wherein the filler is present in an amount from about 10% to 65% by volume of the branched condensation polymer and filler, wherein the branched condensation polymer has a melt flow rate of 10 g/10 min to 100 g/10 min (2.16 kg @ 235° C.).
2 . The ammunition projectile of claim 1 , wherein the branched condensation polymer has a melt flow rate of 10 g/10 min to 80 g/10 min (2.16 kg @ 235° C.).
3 . The ammunition projectile of claim 1 , wherein the branched condensation polymer comprises at least one of a polyamide, polyester, polyacetal, and polycarbonate.
4 . The ammunition projectile of claim 1 , wherein the branched condensation polymer is comprised of a chain scission/endcapping compound.
5 . The ammunition projectile of claim 4 , wherein the chain scission/endcapping compound is present in an amount of 1% to 3% by weight of the branched condensation polymer.
6 . The ammunition projectile of claim 5 , wherein the scission/endcapping compound is comprised of a carboxylic acid or anhydride.
7 . The ammunition projectile of claim 1 , wherein the filler comprises an inorganic compound having a density of 7 g/cc to 20 g/cc and the ammunition projectile has a density of 4 g/cc to 9 g/cc.
8 . The ammunition projectile of claim 7 , wherein the inorganic compound comprises a transition metal.
9 . The ammunition projectile of claim 8 , wherein the filler comprises one or more of copper, tungsten, iron, bismuth, tantalum, zinc, antimony, and combinations and alloys thereof.
10 . The ammunition projectile of claim 1 , wherein the filler has an average particle size of about 5 μm to about 110 μm.
11 . The ammunition projectile of claim 1 , wherein the filler is comprised of a compound comprised of iron having an average particle size of about 25 μm to 110 μm and a compound comprised of tungsten having an average particle size of about 5 μm to about 10 μm.
12 . The ammunition projectile of claim 11 , wherein the compound comprised of iron is present in an amount from about 10% to about 50% by volume of the branched condensation polymer and filler and the compound comprised of tungsten is present in an amount from greater than 0% to about 20% by volume of the branched condensation polymer and filler.
13 . The ammunition projectile of claim 1 , wherein the projectile further comprises an additive in an amount of 0.1% to 10% by weight of the ammunition projectile and the additive is comprised of a lubricant.
14 . The ammunition projectile of claim 13 , wherein the lubricant comprises an aliphatic polyketone.
15 . The ammunition projectile of claim 13 , wherein the additive comprises a thermoplastic binder.
16 . A method of forming an ammunition projectile comprising:
(i) heating a mixture comprised of a branched condensation polymer and a filler comprised of a first and second filler having differing densities and differing particle size distribution to form a molten mixture, and
(ii) injecting the molten mixture into a mold to form the ammunition projectile, wherein the first filler has a density of less than about 10 g/cc and the second filler has a density of greater than about 10 g/cc, the first filler has an average particle size of about 25 μm to about 110 μm, and the second filler has an average particle size of about 5 μm to about 10 μm.
17 . The method of claim 16 , wherein the mixture comprises about 10% to about 50% by volume of the mixture of the first filler and about 0.1% to about 20% by volume of the mixture of the second filler.
18 . The method of claim 16 , wherein the first filler is comprised of iron and the second filler is comprised of tungsten.
19 . The method of any of claim 16 , wherein the branched condensation polymer is comprised of one or more of a polyamide, polyester, polyacetal, and polycarbonate and a scission/endcapping compound, wherein the branched condensation polymer has a melt flow rate of 10 g/10 min to 100 g/10 min (2.16 kg @ 235° C.).
20 . The method of claim 19 , wherein the branched condensation polymer is the polyamide.