Klong said:
I have K&M as well as Sinclair neck turning setup.
What I will tell you is that after using the expander on all my Lapua brass I had to turn down the cutter mandrel. It is easy and worked great. The cutter mandrels where so tight, I could not keep cases in the shell holder. A brief polish on fine sanding cloth, and everything works as it should. I resize after neck turning so the actual expander size is of no concern to me.
Minor point used for clarification only. The K&M Expandiron or Expander uses a Mandrel. The K&M Turner uses a Pilot [smooth regular or carbide with cutting tips] with separate Cutter blade attachment for actually shaving or turning of the brass.
I've used Lapua brass exclusively ... forever. I always use K&M Mandrels in my K&M Expander. And, I've
never had to turn down my K&M Pilots.
Here's what I've noticed.
Sometimes specific pieces of Lapua brass are harder than others. I relate that to their annealing process and believe it imparts a hard crust to the outer surface which in some pieces impedes the expanding of the neck. To solve that issue, I've taken to rotating them and running them through the Expander Mandrel several times.
Because of the "crusting" I mentioned above, I've also noted that once I get past an initial
thinner top layer cut of the brass [I use two Turners] the subsequent pass leading to my goal dimension, precedes much faster and smoother.
Also, at one time I used the Sinclair Power Case Holder and found that because it had a
CONVEX [or rounded] head on the portion that contacted and tighten onto the bottom of the case, that the case would often spin even with extreme tightening of the tool. [I called them and suggested a flatter design]
Once I switched over to the K&M Shell Holder Power Adapter which has a
FLAT head, the spinning went away, because the force being applied to the bottom of case was now being spread out over a much greater surface.