… when materials science renders conventional small arms largely obsolete, or at least makes it so you have to aim better. Â That’s almost the case now, except that body armor capable of stopping a rifle bullet, and even some more energetic pistol bullets, is heavy and expensive. Â Not something your average cop, criminal or citizen is going to wear around casually. Â But what if you could make conventional soft body armor stop a rifle bullet? Â That would have serious military implications. Â I suppose that’s when we move to particle beam weapons. Â But remember, particle beam weapons don’t kill people, high energy neutrons do!