hi viv.
used to use lube over bullets and actually used a wad over a bullet too but now i just seat the bullet...in some reloading books it does say use a wad over a bullet to prevent chainfire if you in doubt just google wad under or over bullet and it does crop up right or wrong.
chainfires can occur either end so use good fitting caps and whatever protection be it lube over or wad under at the other end