Quote:
Originally Posted by Bernie P.
I thought it was the other way around.Run .280 brass through a full length AI die first then fire form.That's the way I do it going from 30-06 down to .280 Rem.After sizing there's a false shoulder from the brass flow.Fire forming drives it out.I do have to be careful setting the die or the firing pin doesn't strike the primer hard enough for it to fire.
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..........I don't see where running a factory .280 casing into an AI die first is going to do anything. You need to fireform the brass in the Ackley chamber first. A properly cut Ackley chamber is about 0.005" shorter than a factory chamber, resulting in a tight seal of the factory round when fireformed. When fireformed, the brass will take on the new 40 deg. shoulder and minimal body taper of the Ackley chamber.I've made .280 Rem. brass from .270 Win. casings and using '06 dies also. Using the .270 brass provides you with a slightly longer neck than the '06 cases, and yes, you do create a new shoulder doing this. That's the new .280 shoulder. Load and fireform to the finished .280 dimensions.
........ I have fireformed many .243 AI brass from factory .243 Win. stock, and the method I described previously is how I do it. I see no need at all to run brass into the AI die before fireforming. It's doing nothing except possibly rounding the case mouth and neck on some out-of-round cases to ease bullet seating on new brass. But, if you want to do it, go ahead.... won't hurt.