Originally Posted by ar15barrels
OK, no brass in the shellplate at all.
Run the ram all the way up.
Snug down the two support dies against the shellplate with all the force 2 fingers will muster.
Lock the dies there.
Then pull the ram back down, add a case and start adjusting the trim die for proper headspace followed by proper trim length.
Randall, thanks again. I tightened down the shellplate bolt and the toolhead clamp bolts, then snugged down the support dies, locked them and set up and locked in the trim die headspace. Didn't even try to add the trimmer motor or vacuum line yet.
On my RCBS precision mic, the initial shells were showing shoulder bump of -.004", right where I wanted them. But when I ran 40 more through the system, the variance is about .007" (from +.001 to -.006).
Not sure what I'm doing wrong. Called Dillon and they agreed with your estimate that the system should be capable of .003" variance.