Usually the AI chamber is cut to minimum depth to insure standard ammo will form. If a standasrd chamber is converted
the chamber will require somthing to hold the case against the bolt face. One other method is to oil the case when fireforming. The primer (not the firing pin) pushes the case forward, oiling the case will allow it to come back against the
bolt and fill out the forward (neck/shoulder) part.
Good luck1