One of the guys in our Artillery Battery was an electronics nerd and he made each of us an electric firing device (a little black box). We shaped the powder charge in aluminum foil with a small flash bulb in the middle connected to two long wires (5 to 6 feet long). We pushed the wires into the bore with a rammer and then fished the ends out thru the flashhole with a small hook. Then gently pushed the powder charge home while, at the same time, pulling the wires up thru the flashhole. Then hooked the wires to the black box. When ready to fire we flipped a switch on the box which armed it. The charge was fired by pushing a firing button. With this little device we could time the shots however we wanted - say one shot every 5 seconds or whatever. Never a mis fire or hang fire. Great for firing a salute at a memorial service, starting a parade, etc.
One of our cannon was exactly like the one you pictured. It had a juice-can size bore and the carriage was painted blue, just like the Revolutionary War pieces. Neat!