Use Snap Caps!!! Mine are purple and less chance of having a ND with them while dry firing as you cannot miss them being snap caps versus a brass case that could have a loaded round in it. I have 3, level 3 vests hanging in the garage on a concrete block wall one on top of the other whenever dry firing and ALWAYS squeeze the trigger after the sights are on the white circle I sprayed on the center of the outer one.
Better to be safe than sorry! Had and heard of numeorus cases of highly qualified LEO's having NDs with their semi's which IMO require a higher level of vigilance when handling.