Actually oddly enough they're trying to not shoot as much lead into the Earth as they used to.

[1]http://abcnews.go.com/Technology/story?id=98594&page=1#....

[2]http://www.firearmsid.com/Feature%20Articles/GreenBullets/Gr...

[3]http://www.huffingtonpost.com/2011/05/04/green-ammo-lead-fre...

Assuming "green" ammo actually makes it into the field, we probably won't see it for a while.