A flintlock is going to have a slight delay. That is just the nature of the beast. But a percussion also has a slight delay as well. You gotta hold that rifle. It really is that simple.

Personally I use 3F in the barrel, and either 7F or Null-B in the pan. That is some pretty fast powder. And should give about as fast of an ignition as possible.

Also your lock might need a good polishing. Some locks are definitely slower than others. Tom.