Wrinkled necks when formed from 6Gren ??

[LaMan]

What's absolutely necessary is to trim the Grendel brass before re-sizing. I've done 100 Starline Grendel brass to 6ARC with Hornady dies without annealing and without wrinkling or any other issues. There is up to 5 firings on the majority of these and only one split neck with some pretty hot loads.