Been down those tracks, then to the hornady tool which is more precise, but now use carbon black on assembled blanks and gradually seat bullet deeper until rifling marks barely show. What I found with sst's is that while the bullet lengths are very consistent to within a couple of thou", the ogive position is not. With sierra lead tips, the bullet length can vary considerably, but the ogive position relative to the base of the bullet is very constant so a properly shaped seating cone is important to use (not just pressing on the bullet tip)
Therefore I am shying away from sst's and moving more towards conventional ogive shaped sierras with constant ogive positions relative to the base of the bullet. I know this works well with SGK 180's and will test their 165's soon. Giving up on secant ogive sst's in the meantime when looking for consistent sub moa groups.
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