Originally Posted by ebsarg
However, on both my rifles (sako 75 30-06 and sako 85 7mm rem mag) even when i screw the die all the way down all the way to the shell holder (at top of ram stroke) the location of the shoulder doesn't change.
Cases can take a few firings to fully expand to the size of your chamber. So if you are attempting to push the shoulder back after only one firing then you are not setting the die down far enough and you don't want to. You need to let the case expand enough to hit the shoulder before you start pushing the shoulder back with the die.
For example here are some measurements taken with a Hornady "Headspace" Gauge (even though not headspace on a belted case) with the proper insert that measures close to the datum line on a 300 win mag:
new case - 2.253"
once fired - 2.270" - neck sized with Lee Collet
twice fired - 2.272" - slight crush fit, neck sized with Lee Collet
3 times fired - 2.2725" - crush fit, push shoulder back
The point is that on the first firing the shoulder was still .0025" from expanding fully to fit the chamber. If you took a measurement on this firing and pushed the shoulder back .001" or .002" and decided that is your measurement and did it everytime, you would be forcing the brass to expand .0035" or .0045" every firing. This would accelerate thinning at the web, shorten brass life and possibly lead to a case head separation.
The best way is to chamber your fired brass in your gun and let it tell you when it is time to push the shoulder back.