only when it hits flesh! the advantage with an expanding round is many. it helps to transfer energy, it creates a larger wound channel, which destroys more tissue, which in effect helps transfer hydraulic shock to the central nervous system. all of these help with the "one shot stop" we all hear about and love. now, if the 45 acp was only going another 300 fps faster! personal defense rounds, except for the very weak, should always be jhp's IMO. in my 380, i alternate, jhp,fmj,jhp,fmj, etc. it is on the weak side, and i doubt it would make 1 shot stops the majority of the time. but, i can carry the thing in my bathing suit. so it is always with me. anytime i can, i also carry my 45.