Which of 2 reamer neck dimensions to use to calculate clearance

[Cassidy]

My reamer drawing shows 0.295 at the bottom of the chamber neck (junction of shoulder and neck) and 0.2944 at the mouth of the neck. Which of these two dimensions should be used to calculate clearance between the case neck with seated bullet and chamber neck. I assume it should be the 0.295 dimension since is the widest and this area of the neck is closest to the bullet pressure band just above the boatail. The case is a 6.5x47 Lapua.

 

[Minesweeper3433]

I am very interested in this as well as 300 RUM reamers have this same taper in the neck on sami spec reamers.

 

[Terry]

My reamer drawing shows 0.295 at the bottom of the chamber neck (junction of shoulder and neck) and 0.2944 at the mouth of the neck. Which of these two dimensions should be used to calculate clearance between the case neck with seated bullet and chamber neck. I assume it should be the 0.295 dimension since is the widest and this area of the neck is closest to the bullet pressure band just above the boatail. The case is a 6.5x47 Lapua.

With a difference of .0006 are we not splitting fractions of a hair?
.003 clearance from either number works in most guns.