Originally Posted by dmax1800
Did you try backing off on your adjustment?
Just a theory;
Take the die down to just kissing the shell holder, then back it off 3/4 of a turn. Lube a case, size it, dry it, feel the chambering of it with the firing pin/spring removed. If you feel resistance adjust down no more than 1/8 of a turn & repeat this cycle until you're just clear of chambering resistance.
Don't tighten the die until sneaking up on a good bump, then back it off a smidge and tighten locked ring with a wrench.
Trial & error(measure)
With careful comparison measurement(depending on shoulder angle), this should put you 1-2thou of head space, which is plenty.
Some FL dies adjusted to shell holder as a 'standard', would set back shoulders enough for ammo to fit in ANY SAAMI chamber. But this could be too much for your chamber(excessive), and shorten case life.
While you had 4thou it was too much IMO. So adjusting downward from there seems counter productive.