This sparked my memory of the modification the Zodiac Killer claims he made:
"…What I did was tape a small pencel flash light to the barrel of my gun. If you notice, in the center of the beam of light if you aim it at a wall or celling you will see a black or darck spot in the center of the circle of light about 3 to 6 inches across. When taped to a gun barrel, the bullet will strike exactly in the center of the black dot in the light. All I had to do was spray them as if it was a water hose; there was no need to use the gun sights.” Source
That’s pretty wild for 1910.
This sparked my memory of the modification the Zodiac Killer claims he made: