Pete,
Congratulations. I'm looking at a manufacturer of firearms license as well, just to make and sell a few in a larger diameter action/bolt configuration.
A manufacturer of firearms licence covers both rifle actions and ammunition both, but a manufacturer of ammunition license only covers ammunition, not actions... ammunition license is only 1/5th the cost however. To work as a gunsmith, just a dealer license is required. A seperate importer license is also necessary to import firearms for sale, and form 6 must be filled out and approved to import for a nonlicensee or licensee's personal use if one does not hold the importer license.
A seperate dealer license is not required if one holds a manufacturer or importer license.
Destructive device licenses are seperate for each of these catagories as well and cost is substantially more for each, about 20 times more.