That last 1/16" is where 90% of the sizing take place. The cases have a tiny bit of taper to the whole length. That is where it all contacts the die's inner surface. That is also the time and place you cartridge shoulder is set back. (since it is a bolt gun) You might think about raising your die 1/8- 1/4 turn to keep from over working the shoulder.

Since the is an accuracy project. Cast bullets don't really like to be crimped, We need to if they are used in a multi shot gun. But if you use the bolt gun without loading the magazine, just straighten out the case mouth bell and let neck tension do the work. (we do this all the time in Sharpe's and High Wall rifles) Try to make your brass have the same neck wall thickness, by turning or by sorting. 1/2 to3/4 of 1/000" should be the limit. The easiest way to measure is with a tube thickness micrometer but there are other ways that use arithmetic and 2 measurements per neck. If you can see the neck thickness be off balance, that case needs turned or retired.

Ivan