Brad has the correct take on this subject. What we call full wadcutters were begun in the 1920's seated into the case. The earliest were seated to the same length as RN. Two things happen with deep seating: less powder, less recoil and you can load a bigger bullet. Wadcutters are commonly .360+ inches so the factory round is a snug fit into the chamber and not lying on the bottom of the chamber. When I was in LE in the '70's we would load WC's 1/2 out of the case with 5.5 grains of Unique. After a shooting, it was just practice ammo, forgot to put the RN's back into the revolver. HTH, Ric