My hornady reloading manual says that I should seat their 140grn bullets out .080 farther than their 130grn bullets. I have measured them from the land diameter to the tip and they are exactly the same. I have also measured them from the cannulure to the tip and that is also the same. What would be the reason for this?

Assuming that the 140 gr. bullet has a longer overall length, I suspect that case capacity may come into play. If you can, call them up and ask them.

gd

Different ogive?

There may be a difference in the ogive between the two bullets. Because of the shape of the ogive the 140 gr may actually be the same difference to the lands (distance from the lands to the point on the ogive where they would contact) when seated .080 farther out. The point of the bullet doesn't touch the lands but the side of the bullet (called to ogive) actually touches the rifling. Shorter, lighter bullets often contact the lands closer to the tip of the bullet than longer, heavier bullets.

What I don't understand is...both bullets contact the lands at the same distance back from the tip,yet they say the OAL for the 140grn should be .080 longer. Any difference in the ogive forward of that point should'nt matter.