If I already have carbide expanding balls for my Redding dies, can I use them to expand the case prior to neck turning?

Yes, the case will fit better on you pilot collet so you get a better cut. You will have less problems if you make two cuts to get down to the thickness you want instead of one thick cut. Good Luck

MY GUESS IS NO. If it is a "sizing" ball from a die it should leave your case mouth undersized from the caliber diameter. You actually want to be slightly oversized. ONLY a trial will tell. But, it you don't have too loose of a chamber you may be able to cut unsized 1x fired brass and escape the whole beginning process.

I agree with Kraky. I love those carbide sizer buttons for reloading but they are undersized such that the case neck has proper tension to grip the bullet. Prior to case turning I use a Sinclair expander that is oversized by 0.001 inch. Believe me, even with lube, it's much easier to turn necks after passing through the Sinclair die than it is on an unfired case or worse yet a sized case.

Good luck.

Reed