US army looking at polymer bullets for larger more lethal calibers but lighter weight

The US Army is testing new guns and ammunition to replace the M4/M16 assault rifles. The 5.56 mm ammunition is not as lethal the in the over 300 meter range where many modern firefights are taking place.

SOCOM is also developing polymer ammunition in 6.5 mm to reduce the weight load.

Current research is showing polymer 6.5 mm reducing weight by one-third from 7.62 mm, reaching nearly the same weight as conventional brass 5.56 mm.

Textron Systems, a private defense industry company, conducted a caliber study using a specially designed .264 (6.5 mm) caliber cartridge which they said resulted in "terminal effects greater than 7.62 mm NATO out to 1,200 meters" in both their carbine and machine gun.

Data provided by the company showed the machine gun is 7 pounds lighter than the 7.62 mm M240L with 800 rounds of their lightweight ammunition, lowering the combat load by 27 pounds.