I've been on the fence about smokeless in it. I know our Ballard expert has always used it, and I'm sure it would be fine with light loads. Yet, at this point I've only shot it with black powder because I know, without a doublt, that's what it was built for. The last Ballerds were made long before Smokeless. In the Colt Single Action world, today everyone says you should never shoot a BP revolver with smokeless. Of course, most were during the 20th century. On the other hand, I'm not sure Ballard actions of this type were ever chambered in the .25-20 SS, they mostly shot a few long Marlin rounds. On the other hand (Fiddler on the Roof), those would have been about the same pressure...
I've sighted it in with FFF and cast Ideal 86 grain 1:20 tin to lead. It was showing potential, but I ran out of time that day. Need to go back.
With the early days of smokeless starting around 1895 a lot of BP firearms got shot with smokeless loads. Most with factory loads, and soon after by reloaders who began reloading with smokeless powders. I'm pretty sure back then shooters weren't as conscious or wary about using smokeless cartridges in their BP era guns as many are today.
Proper smokeless powders today are much safer than those early days when powder choices were limited, and low pressure smokeless powders didn't even exist. There are a number of smokeless powder choices today that operate at lower pressures than BP does when loaded to BP velocities. The key is using these low pressure powders and keeping velocities down to BP velocities. A good ballistic program also helps a lot for those new to old firearms like the Ballard rifle so you can not only see pressures and velocities, but also see a graph of pressure rise to know how fast a certain load reaches the pressure level and velocity.
Loading smokeless might not be for everyone, but it can and is done often and safely if care and knowledge is used in building ammunition. I've been shooting smokeless in my Ballard rifles for over 45 years now safely.