The write up I seen stated the case was coated with a polymer coating.
There are many different coatings/paints out there. But one that come to mind is acrylic
floor finish, very durable, water based, ease of application, and the tip of the bullet can be coated.
Just run the loaded rounds through a wash then let dry. Case is coated for extraction and the bullet tip
has a coating the will help it slide between the fibers of a vest.
The guy's want that coating removed might want to try a floor finish remover located in the household products section.