Re: Neck turning issues
If you measure neck wall thickness, then you should know what it is.
You said some necks come out .268, some .264, and some .2705.
That means nothing.
What are the thicknesses coming out like?
Or, when you seat bullets into these necks, what are the loaded OD measurements?
Whenever turning you need a matching system. That is turner, cutter blade, turner mandrel and matching neck expander. I don't know if Sinclair's expander will result in proper fit to a Forster turner mandrel after a neck is expanded & sprung back. It might.