"Flintlock" simulation

Okay black powder and other reloading creative thinkers:
Navy Seal museum here in FL has commissioned a sculptor to make a 3D oversized outdoor representation of the UDT (eagle, trident, flintlock) uniform device.
The guy making the thing is a friend and he was thinking of hiding like a snake charmer or other single .410 in the flintlock so that it could be fired and wanted some blanks to create the flash, smoke, pow. I suggested cowboy .45 LC blanks like they use for balloon and quickdraw but that may not have the wow factor I think he wants.
So I started thinking about reenactment charges of perhaps a larger caliber. Almost a hammer fired cannon simulator. I don't know if the thing will be "fired" by a trigger pull or remotely but the guy making it certainly has the creative skills to use the traditional looking parts to get a firing pin to strike.

So, if you got the call about this, what path would you follow?

Interesting question! I will give it some thought.

flash paper or nitrocellulose will give a nice muzzle flash, don't need a lot of powder to drive it either. I'd recommend talking to someone in the film/special effects industry if he knows someone like that.