JAWZ, yep +/- 0.001" or 0.002" overall. I'd do +/- 0.0005 as does Boss Hoss, but my equipment is pretty much crap. Plus I shoot only rocks and aminals
which are a little more forgiving than putting the calipers to a group on a target.
Boss Hoss - yes I'm striving to measure actual bearing surface. With the tools I'm using I have to determine, as accurately as practicable, an average boat tail length, then measure ogive to base the do the math. As part of my overall process its working well but as I extend the range beyond my current confidence distance I'm going to have to upgrade some equipment.