Thread: Olive length changing?

One thought...
SAAMI specs for 308 say lands at 7.62mm and grooves at 7.82mm. So I assume this means 308 projectiles are actually greater than 7.62mm diameter, otherwise you won't get any rotation from the rifling. .308 of an inch is actually 7.82mm
If your comparator insert is 7.62mm (or anything less than 7.82), it is actually contacting just before the true end/start of the ogive, and how far before the ogive will be affected by projectile shape. And the insert has to be at least a bit smaller than bullet diameter or it could travel the full length of the projectile and you wouldn't be able to get a meaningful measurement.
In effect, you are probably measuring where the projectile diameter equals the diameter to the lands, not the true ogive point. But that is what you want anyway to be able to set your jump so all good, but the measurement will vary slightly between projectiles.