I don't use aerosol or spray case lubes, but on new brass I lube case mouths with graphite on a brush or necks and mouths with Redding Imperial dry neck lube and their ceramic bead applicator. For sizing, I use regular Imperial lube applied with finger tips. I worry less about mouths on fired brass, if it hasn't been cleaned and retains carbon residue inside the case mouth so long as runout remains very minimal and seating depth is consistent.
