Depends on what they want to advertise them for. (use)
I would suggest loading them with 40-45 gr of Pyrodex "P" and WRLM primers for BP shooters.
This load with 777 or APP would also work. (load down the 777 to 40gr or less...no use having it go over 1200fps)
[I have heard that using real BP in carts will get you bumped up into the "explosives" cat. for a show.]
For smokeless, IMR 4227 or TrailBoss works great. I have used 9.2gr of Trailboss in my 350gr loads and gotten right around 950fps with WLR primers. (TB is MUCH cleaner and less case sensitive, as it fills over 3/4 of the available space)