I just tried JSG and was well pleased with it so far. Out of my T/C NewEnglander and my Lyman Mustang I have had perfect ignition every time and groups that equal Pyrodex or BP. No crud ring at all in either gun.
I'm using 100 grains off fffg in both rifles. Probably pushing a max load for the T/C, but no indication of excessive pressure. I was suprised as to how well it ignites in the sidelock with CCI #11 magnum caps - no delay at all.