You're getting some resistance because you're sizing the brass exactly to match your chamber dimensions... there's no room for error. The brass has a bit of "springback", some less, some more. Some fit perfectly, some not so much.
In spite of Mr Guffey's objections, many people find best accuracy when the cases are sized about .001 "shorter" than the chamber. "Bump" the shoulder back .001.
Die threads are typically 1/14 pitch. That means an entire turn is 1/14th or 0.07 of an inch. If you go for .001 bump, it's hardly any additional turn at all, 1.5% of a turn, roughly.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.