A neurosurgeon friend of mine told me a true story as follows. A recently immigrated Somali guy came to the clinic complaining of chronic headache. Imaging was done revealing a 7.62mm bullet pointing vertically down at the back of his brain. Questioning revealed that he had not been in any conflicts but had been in celebrations with gunfire. What goes up from an AK47 comes down.... They had to leave the bullet in place.