Actually, the Booth Derringer, as others have noted, was a percussion firearm, not a flintlock. A percussion cap was fitted over a pierced nipple (yes, that is the correct term) to ignite the powder in the barrel breech and fire the weapon.
However, although the FBI purportedly examined the weapon and bullet in 1997, the bullet was determined to be too corroded for any reasonable ballistics testing, so it "probably" was a .44 caliber lead ball. You can check these facts @: http://wesclark.com/jw/booth_pistol.html
However, although the FBI purportedly examined the weapon and bullet in 1997, the bullet was determined to be too corroded for any reasonable ballistics testing, so it "probably" was a .44 caliber lead ball. You can check these facts @: http://wesclark.com/jw/booth_pistol.html