I've recently purchased second hand loading kit set up for 308 of a mate.
I set the press ram up and wound down the head seater die up to it as seen on Internet. My problem is that when I put my case in and close the press I have about 1 mm gap between head and ram.
My mate doesn't have the gap on his press. My brass case is 51mm long. The danger is if I force the press I can actually deform the case.
I have cleaned the die head and it seems fine.
I have got over the problem by inserting the case on the ram and fully lift, then winding the die to it and then off half a turn. Then screwing g the adjuster down to seat the head to the correct depth.