JSG is a very good clean burning powder. It is not as powerful as Pyrodex or 777 but it is one heck of a lot cleaner. JSG likes a tight fitting sabot seated very hard
on the powder. Some of my best groups were made with JSG. Killed a hog at a lasered 192 yards using my Encore loaded with the 250 grain SST and 90 grains of JSG.
It is nice not to swab between shots. There is no crud ring to deal with and one can remove the breech plug without a big hassle.
For some time now i have been using Goex Pinnacle powder made by APP. Pinnacle is more powerful than JSG and it is also very clean burning. Hodgdon has dropped Pinnacle from their Goex line. Maybe APP will make it available under another name.