http://phys.org/news/2016-04-metal-foam-obliterates-bullets.html The CMF armor on collision literally converts the projectile into small particles, spraying out. This is interesting and definitely not my area. Watch the attached video. Questions: 1. the particles resulting from the hit have to have kinetic energy, if some particles are redirected to unprotected area (example: projectile hits high, just above the top of the sternum, redirect up into the lower jaw), are they a problem? 2. Impulse from the collision should push the armor back into the wearer of the armor. Correct? There should be some negative consequences to the wearer at the point of impact. Assumption: There is no free lunch, if you ameliorate one issue, in this case severe or fatal wounds, then there there has to be some trade off. Please correct me.