Bill, I agree with you that the correct way of describing bore and choke is with measurements for both as you've described. But you can get there either way. If you do it JDW's way, you just subtract the choke reading from the bore reading, and you have your numbers, i.e. (.665-.030=.635) Different way of getting to the same place. Of course, there is always the possibility of losing a .000 or so in the process, but in the scheme of things not really relevant.