Try marking your cases as to left or right barrel and do not swap them. After initial fire forming you should not need to do more than neck size and perhaps crimp. Indenting the case with the factory tool is not in my mind necessary, a mild or taper crimp with a die is all that is needed. You will need a crimp of some sort, as the recoil from one barrel may dislodge the bullet in the other barrel. During your initial experimentation of loads, fire one barrel then examine the loaded round in the second barrel to see if the bullet has been moved by the recoil.
Harry
