Ogive
The curve of a bullet's nose, the shape between the straight bearing surface and the tip. It sets both ballistic coefficient and seating-depth measurement.
Bullet ogive shapes include secant (a continuous curve toward the tip), tangent (a smoother transition), and hybrid (a combination, like Berger’s match bullets). Secant ogives produce higher BCs but are more sensitive to seating depth and jump.
For handloaders, the ogive is also the reference surface for CBTO measurement. A bullet comparator clamps on the ogive at a fixed point so seating depth measurements stay unaffected by variation in the bullet’s tip.