"...to ogive..." Ogives do not apply to OAL. OAL is measured from the pointy bit to the flat bit.
Ogives apply to the off-the-lands length. That's different for every rifle chamber. Even two identical, consecutively numbered, rifles will have chambers that are slightly different and each will prefer a different distance from the lands.
The whole off-the-lands stuff is a load tweaking technique that doesn't make much difference in a hunting rifle, anyway. It's mostly a benchrest technique that's gotten out of hand on the assorted internet forums. Isn't really necessary.
Throat erosion takes a very long time and thousands of rounds. Doesn't apply to hunting rifles either. Does somewhat to target rifles.
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