All I use isPyrodexor Goex BP in all my muzzleloaders. The only ignition problem I ever had was with a T/C NewEnglander 12 ga barrel. Pyrodex usually had slow ignition with the origional #11 cap ignition. A change to musket caps solved the problem. The .50 cal barrel for the same gun works fine with Pyrodex and #11 caps.
I usually use Goex FFG with the 12 ga. anymore, though.