ORIGINAL: Pawildman
ORIGINAL: goatbrother
If the fire form loads have a headspace issue try using a 30 cal neck expander then when you neck down to .284" set the die so the case headspaces on the small shoulder formed from the 30 cal expander. A buddy has a 270 Gibbs, the case shoulder on that round is moved more forward than the Ackley improved and that is what they did to get the cases to fireform.
That's basically what I used to do to make .280 brass out of .270 Win. years ago when the .280 stuff was scarce........
This would be a wise practice for making .280 cases from .270 brass, as the .280's headspace measurement is oonger, the idea being to prevent some turkey from chambering a .280 round in a .270 chamber. If you used .30/'06 cases to make .280 brass, all that need be done is size the neck down until the case will justy permit the bolt to be closed with a little extra force on the bolt handle.
It could be done with .280 brass in a .280 AI chamber as well, but would not be necessary if the .280 AI chamber is properly cut. The headspace specs for the standard .280and the .280 AI are the same. IF you were forming 7mm Gibbs cases, it would be a different story!