AFAIK, Colt never made a single shot pistol
They do not make a nine shot pistol made by Iver Johnson. These pistols were available in the 1940s.
What is the value of a Davis Derringer pistol magnum 2 shot?
200 yards
They made thousands of them.
50 cal barret
They have been made.
Impossible to answer without knowing who made it.
Maybe 70 USD
No, if it was designed to be a single shot, it's a single shot. It needs to be reloaded after each shot.
1 centimeter
@ 2000 and 2400 M