Although it can be done, I'm not a big fan of fireforming any AI caliber with the cornmeal method. Pressure has to be at a certain level to properly form the body and shoulder angle. And since the only point of contact on an Ackley Improved chamber, when initially fireforming, is the juncture of the neck and shoulder; the firing pin strike can push the case forward into this contact point.With the cornmeal load, this can sometimes cause primer setback, creating a subsequent headspace problem.

AI chambers should be set up to where the bolt closes with some effort on a factory or virgin brass case anyway . . . but unless you go to a reduced power striker spring in the bolt, I would stay with the tried and true method of fireforming using a bullet and powders like IMR 4198 or H110- just enough to form a sharp shoulder angle.