Doc,
You remind me of a friend that hit a gong at 150 yards offhand with my 2nd Dragoon once; I had one shot left in the cylinder and no more caps with me, and I had promised him a chance to shoot it. We were shooting 25 yard paper targets and he reminded me of my promise. I expected him to shoot the paper but he didn't want to pollute my tests, so he went over to the rifle range, raised the gun one handed and fired downrange. We heard the gong but nobody else had fired, so it must have been him. His response: "Not bad, but shoots a little high, eh?" Lucky for him I was out of caps...
Yeah, the Derringer is a lot of fun. I think you get lots of smoke because all the powder goes out the barrel, and the unburned powder in the cloud of ejecta is ignited by embers in the same cloud. You normally get a lot (some say up to 50%) unburned powder staying in the barrel, but the derringer barrel is so short it all gets pushed out and ignites after the fact.