Quote History Originally Posted By tzzler44:
I'm using a Whidden seating die. I'm measuring from the case base to the ogive of the bullet, not the tip. These were sized on a Mec Marksman with a Redding FL sizing die set for a slight cam-over.
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You did not mention taking any steps to address differences in shape bullet to bullet.
Bullet seaters do not push down on the bullet tip, nor do they push down on the point on the ogive you measure to. They push down on an unknown point between the two, and the distance from there to your ogive measuring point can and will vary bullet to bullet.
Should you choose to deal with this variation, IMO the best way is by seating long, measuring CBTO, and then adjusting your micrometer seating die so that the second seating results in your target CBTO measurement. In that way all cartridges will have the same distance from bullet ogive to the lands . . . which presumably is the reason you're measuring CBTO in the first place.
Others may advocate sorting bullets by ogive length or bearing surface length, but IMO neither of those deals with the fact that this particular source of variation occurs between the bullet's ogive (ie measurement point) and tip.