The lower density M22 bullets were of the same shape as conventional M2 bullets for reliable function through self-loading machine guns, but weighed only in comparison to for the M2 bullets. In the early 21st-century, the United States military began using frangible bullets to reduce ricochet risk during small arms training. These bullets use nylon as a binding agent for a core of powdered copper and tungsten contained within a gilding metal jacket. References Bullets