RE: Rain proofing your Black Powder gun.
I do the same as Criggster, only with a balloon over the muzzle when its really pouring, and electric tape over my Knight's FPJ (Wolverine) when Im still hunting/stalking. My Revolution, and my buddies Vision are fine in the rain, so I dont think you have too much to worry about...
Maybe you could try a piece of tape over the action (where it breaks)...
Good Luck!