Ok, what am I doing wrong - necking down 7mm Mag to 264 WM

[Bbear]

A friend gave me a partial box of brand new Nosler 7mm Rem. Mag brass to use in my 264. The first few I ran through the sizing die have the dreaded doughnut at the base of the neck.

What did I screw up this time? Or, did I just not hold my mouth right?

Any help appreciated.

 

[Mikecr]

You can expand and fire form out the thicker brass. Speaking of that, sized down necks are thicker across the board. Do you have enough neck clearance for this?