Originally Posted by Mikecr
Gene, an 'ogive' is not a particular place on a bullet nose.
Bart described a place furthest forward on the nose that still provides good readings.
No standard place on the nose is associated with bearing, or even leade contact, as this varies with local factors like leade angle, and ogive radius & type.
Also, ammo axis, to any centerline, really does not correlate directly with TIR.
Runout is not eccentricity. They are different things.
Mike - I agree with only the third line above (i.e., no place on the nose is "bearing" on the lands). Bearing surface relates to the shank end of a bullet. We commonly refer to ogive as the transition point between the shank and curve toware the tip, for lack of better reference. Reading TIR anywhere but on the shank (just behind the transition) can lead to considerable inconsistencies. I don't know of any one who spins a bullet anywhere above this point.
Runout is a misnomer. It does not imply either concentricty nor eccentricity. If runout on the bullet, as spun on the concentricity tool, is very minimal one can assume the neck and bullet are straight and the bullet will be centered when engaged to the bore.