I would not lube our NSA slugs, .300 caliber and below. We clean our slugs and then dried under fans. After they are dry they are lubed and lightly tumbled to get the lube even and then bagged and boxed. We have switched to a silicone lube that is very slippery and seems to be very good and leaves a nice finish too.
Before that we used Slick 50 in a spray can which I used for years and works nice. The issue with it is it leave a residue which does not leave the bullets looking as nice after it sits on the lead over time.