I have loaded plastic cases, plastic wads with black. Works fine once but don't expect many reloads the biggest problem is volume. You can end up using a wad designed for 1.5 oz shot and barely having room for an oz of shot. About 100 years ago there was a wad called a "LAG Unwad" It was simply a cup with an insert in the cup that crushed to compensate for volume. Ideal for black and 2 inch shells but I have not seen any for years.
bill