Yes, I've seen several examples of the brass 1849 Colt "Pocket Model" .31 caliber with the "COLT'S PATENT" maker mark.
I think most of the .36 and .44 caliber molds were made of iron, however you still run across .31 made of iron as well.
Not sure about the .28 Cal Root Revolver, I think the ones made by Colt could produced a round ball or a conical bullet.