Pyrodex RS is all I've had the opportunity to shoot in my sidelock so far and it might be all I ever shoot unless I just get some money to spend and some time to kill and try different loads. I like what I'm seeing with it so why change? I was having the hangfire problem but I took a suggestion of cayugad's and more or less sanded the nipple some so my caps would seat better and the problem went away. I have a Hot Shot that I plan to put on before I go out for another range session, though.