I hope this ? is clear - Sinclair seating depth tool question

[RedRyder]

I use a Sinclair seating depth tool with comparator to achieve a starting OAL measurement. Sinclair instructions say to measure the bullet, base to tip (Berger 130 1.375") then add it to the measurement obtained after using a chambered case to make a second measurement (1.556). Then to add the two measurements together = 2.931. I've used measurements based on this number (but actually measuring case base to the ogive 2.175 ) with good success.

But while I use the case measurement (1.556), I've begun thinking that it would be better to use the bullet base to ogive measurement (.68), which would produce a longer cartridge (2.248).

My question is which method is more accurate?

Thanks very much

 

[high right]

I've used the same tool for a couple of years now.
I measure to the ogive and keep THAT bullet in a baggie with the
original measurement for a base value on throat wear. Use a fired, sized case
With the fired primer for your chamber measurement. Keep that case with
the bullet and your good to go. Much more accurate and repeatable than
the Hornady.