Aguila Blanca
Staff
It is correct that pistol caliber hollow points expand but don't upset, and that upsetting is a function of bullet length and shape (center of balance), velocity is not a factor. The reason 3,000 fps is important for the 5.56 M16/AR-15 round is that the effectiveness of the bullet lies in having the outer jacket fracture when the bullet tumbles upon entry. Above critical velocity, the centripetal force generated by the tumbling tears the case open at the cannelure. The minimum velocity is necessary to generate the fracturing. Below critical velocity, it's just a .22 caliber hole.RC20 said:The SD/HD hollow points DO NOT upset. Thats a 5.56 round characteristic (3000 fps area) that has to do with the bullet length and velocity).