Why is a turret press better than a press with a quick-change bushing?
It's probably not any better, but it's not any worse either.
and
Does a turret press give the same kind of SD for head to datum resizing and head to bullet ogive seating as a good single stage?
Yes, at least as close as it can be measured accurately.
A lot of emphasis is placed on alignment of the ram and die when comparing conventional presses to a floating head press. But, as the brass is pushed up into the die it "follows" the die. A certain amount of slop is present in a conventional press with a conventioal shellholder and that allows for the brass to follow the die as the brass is run up into the die. A floating head like the CO-AX is doing what is already happening with a conventional press. Up to a point at least. I didn't get any straighter ammo with my former CO-AX than I do with a conventional press.
Knowing what I know now I would buy a turret press. Based on friend's experience with all three, Redding, RCBS, and Lyman turret presses all work well.
