eric n
Silver $$ Contributor
Got it now. Thank you for the response.No. What's missing in this thread is declaration of WHAT comparison to discuss. There are different kinds.
The BGC rests on two datums at once.
#1 a bullet inserted to stop at a datum near land contact
#2 an indicator with a seating stem (like Wilson's) rests against the bullet nose forward of #1
The measure here is the distance between the two datums, and is showing ogive radius variance.
The value in this 'comparison' from bullet to bullet is in matching them -so that all other measures off ogives are qualified (to any matched standard).
Now with qualified ogives, it does not really matter where on bullet noses where you set datums.
The Sinclair 'nut' cursed as inadequate, is totally fine. Yes it does not represent land contact datum, but neither does any other tool unless it's cut to same throat angle as your chamber.
Do full seating testing, measure (with ANY tool) your best CBTO, and always use THAT tool to recreate the condition.
Just keep in mind that until you've qualified ogive radius, none of what you're measuring from a bullet nose is qualified. I don't know if Erik knows this, but ogive radius is the base from which to begin discussion w/resp to CBTO.