How do you load a butler derringer?

Simple.

Hold the gun upright with the barrel facing left, "break" the gun sideways (away from you, just in front of the hammer. Then insert the cartridge. If the gun has not been opened, lubed, etc., for a long time, it may take a gentle rap with a SOFT mallet. There is a spring loaded "button" beneath the barrel on the inside that may be a bit stubborn- but that is what holds the barrel closed.

IMPORTANT- do NOT load the weapon before determining that the barrel is clean and unobstructed, and the pistol is in good working order.

You're welcome,

Concrete Pete