One thing I've not seen mentioned in this thread is using shell holders with different heights above their bottom where the case head rests.
Redding makes these in .002" increments. While the "industry standard" seems to be .125", with the die set to "bump over" when the ram's all the way up, bottleneck case shoulders are set back to SAAMI minimum; sometimes even less. Redding says about these shell holders that come in a kit:
Shellholders are packaged in five piece sets in .002” increments (+.002”, +.004”. +.006”, +.008” and +.010”). Each shellholder has a distinct black oxide finish and is clearly marked to indicate the amount it will decrease case-to-chamber headspace. You can now easily adjust the shoulder bump to customize cases to your specific chamber.
They do work very well and help keep sized case headspace spread to a minimum which is essential for long case life and accuracy.