Most of my die sets tell you to raise the ram and screw the sizer down to contact the shell plate. Release the ram and screw the die down about 1/8 to 1/4 turn and lock. With no case in the press, raise the ram and you should feel definite resistance when the top of stroke "cams" over.
Carbide dies are NOT set up the same.
That being said, I find not only that some brass is harder, but anything that I run through my M1A is harder to reload to work well in my bolt M700.
It does not seem to make any difference whether I am shooting commercial brass or military surplus.
The rounds I have problems with trying to run in the bolt gun almost always have the typical hard ejection marks on the case that is typical of the M1A.
I do not always do a good job of segregating brass from the M1A from the