.22 RF is the only ammo I knew semi-smokeless was used for.  I’ve read it was primarily BP with enough smokeless mixed in to burn up most of the BP fouling.  Some .22 target shooters were still using it into the ’30s.

Chuck said
What is less smoke powder?  Is it just a way of saying smokeless?

  

Not at all–means exactly what it says: “less” smoke than BP, but still some…which annoyed competitors shooting straight smokeless, who complained it drifted over to their positions.  In many brls, semi-smokeless was more accurate than the smokeless then available, which was why it remained in use almost up to WWII.

Do yourself a big favor & buy “Peters & King,” by Tom Shiffer, one of the most fascinating gun books I have, & have many. 

Chuck said
Thanks, couldn’t you pick one that isn’t so pricey?  

Didn’t know that!  Paid list for mine.  However, if any gun book deserves a premium, it would be this one.  Tell Krause it should be repub, at least in soft-cover.