Bought a used seater die and was reading about how to clean it. Got it apart and it was really gummy from old dried oil. Anyway, got the main part all cleaned up and was getting ready to clean the bullet seating tube and I noticed a black coating on the inside and wasn’t sure if it should be removed or not. My guess is that it might be Molly residue from the previous owner seating a lot of Molly coated bullets.