bulllets. The HP cavity has to be nearly to the front of the grease groove, so that the Split NOse will break-apart at that groove. The tricky part is determining how deep the hb can be, and not have the powder gases blow a hole thru the bullet. What my friend did was deepen the HB unti the gases DID blow a hole thru into the HP cavity, and then he backed-off the depth of the hb hole until there was never any problem. See, unlike you lames, HE is willing to spend the time and money to get real PERFORMANCE.