The seating stem engages the Ogive, except in cases where the seater is designed for a flatnose bullet, and truncated cone shapes with handgun bullets. The Ogive, or the tangent of a bullet is the only part of a bullet, besides the full diameter shank that is of concern with headspace, or freebore. Speaking of which, wasn't there a band in the 60's or 70's called the O-Gives?