Originally Posted by jeffwhip
What kind of casing were you trying to fire form from? Is that a 30-06 case?
I fire-formed 100 Lapua 30-06 brass to the 280 RCBS Improved - 30 degree shoulder. About the same thing as the 280 AI, but with slightly less angle on the shoulder. It can be done. It does take a bit of time and fussing. I believe I annealed the case neck shoulder junction prior to fire-forming. The shoulders blew out just fine on mine. As I stated in my PM to you, the bullet must be jammed into the lands, and tightly enough so that the case head cannot leave the bolt face when the firing pin strikes the primer. I believe I used 175 grain Hornady round nose bullets for purposes of fire-forming.
Once the initial fire-forming is completed, 100 Lapua brass will last close to the life of the barrel, unless you run them near top pressures.