Initial objectives were elimination of ozone-depleting substances, volatile organic compounds, and heavy metals from primers and projectiles.
The materials generated hazardous wastes and emissions at manufacturing facilities and use of ammunition caused contamination at shooting ranges.
[4] October 11, 2013 Governor Jerry Brown of California signed into law AB 711 Hunting: nonlead ammunition.
Switching to the 5.56 mm green bullet, the M855A1 Enhanced Performance Round, or EPR, in 2010 has eliminated nearly 2,000 tons of lead from the waste stream.
Increased pressure causes gas port erosion producing a higher cyclic rate of automatic fire making jamming malfunctions more likely.
The lead-free cartridges also reduce environmental impact by removing more than 2,000 metric tons of lead per year that otherwise could end up in the environment.
[18][19] The EPR contains an environmentally-friendly projectile that eliminates lead from the manufacturing process in direct support of Army commitment to environmental stewardship.
Twist was increased to 1:9" after combat experience demonstrated the advantages of longer 62-grain (4.0 g) M855 bullets with a portion of the lead core replaced by a less dense steel penetrator.