Real black powder has a lower ignition temperature than the subs...(Due to the sulfer)...This is why experienced flintlock shooters stick to the real thing...Thankfully, I live about an hour from a Goex distributor...I use FFF as the main charge in both my .40 and my .54 and have used both FFFF and FFF in the pan for both...When hunting, especially when damp and rainy I never use FFFF as the pan charge, I stick with FFF as it doesn't absorb moisture as readily...