Most reloaders forget about the shell holder, the shell holder has a deck height, again, it is a burden but I must be the only reloader that measured the deck height of the shell holder. I use shell holders with a deck height of .125". A shell holder with a deck height of .125" can be used with any die manufactured sense 1960 +/- a year or two.
So? I do not know what part of the case head you are measuring but it is impossible to size any part of the case head below .125" because of the deck height of the shell holder. After that there is another consideration, the die had a radius, the radius prevents the die from sizing the case head below .125 + the radius. And then there is a great big problem with reloaders, rather than think about it they had rather act silly.
There is no shortage of small base dies around here, it is not fair but I find it most difficult to measure the difference between cases sized with a small base ide and a 'good fitting' standard die.
Before the Internet and anti social media: There were different chambers meaning the same ammo that was designed to be fired in the 03 and M1917 was issued to be used in the M1 Garand. I could ask, "How could that be?' but I am not in a crowd that would understand the question.
And then there was Browning, Browning made semi/auto 30/06, 270s, 300 win Mags etc.. and I ask , "What was a reloader to do?", Anyhow I have 6 sets of dies that are labeled BAR dies. The BAR identified the dies as small base dies for Browning Automatic Rifles.
I could ask: What to do if a reloaders does not have small base dies? I have used the feeler gage between the deck of the shell holder and case head to increase the ability of the press to overcome the ability of the case to resist sizing and increase the ability of the press/die to shorten the case from the shoulder to the case head. This method has never failed me. Other reloaders? They spend all of their time 'bumping' and talking about it. I cant talk about bumping the shoulder because I can not bump the shoulder with a die that has case body support.
F. Guffey
This is flat-out frickin amazing!!!!