I've cast & shot the 1 ounce slugs, never the 7/8 ounce ones. I use WW for the casting.
"I burn a candle (bees wax) and smoke the mold make sure the mold is hot before the lead is added "
Very good advice.
A 20 Gauge Nitro card, or cut your own out of a matchbook, gasket material, etc., in the wad under the slug will prevent the occasional wad sticking into the slug and giving you a flier.