Two assumptions I have. Black Powder would be made in small scale plants to match the smaller need today? And that smokeless is a totally different process (extruded or whatever), and those plants cannot make Black Powder?
Exactly! Smokeless is nitrated cellulose dissolved in a solvent out through a die into water where the solvent is removed. That is the quick way of describing it. When you look at the history of black powder manufacturing here in the mid-Atlantic states you see little single man or two "plants" in rural areas. We have a powder mill road outside of Reading. Some guy with a farm and his son made small batches of hunting powder in his spare time to supplement his farm income.
North of here at Schuylkill Haven there was a small BP plant that made shooting powders for the locals in Northern Berks County and Southern Schuylkill County. In my younger days I hiked the mountain near where the old plant was located looking at all of the old charcoal pits. Since they did not make blasting powders du Pont left them alone and did not buy them out or burn them down when du Pont started to take over that area. Du Pont even sold them sulfur and purified potassium nitrate to help them stay in business into the late 1800s.
At one time there were a host of small black powder plants up North of here serving the anthracite coal mines. Then when Lammot du Pont put together the "powder Trust" the plants were bought up. Those who refused to sell were subject to week end fires when everybody was away from the plant.
To put together a small plant today is nearly impossible. Try finding a working wheel mill. The other machinery you will have to hand build. And good luck dealing with state environmental officials.
A good friend of mine tried that in Australia back in the 1980s. The territory govt. shot that down. He had a small wheel mill and a 5-ton wheel mill plus a real powder press. They kept fining ways to tell him no even though his property was 40 acres out in the bush.