http://www.rockislandauction.com/viewitem/aid/65/lid/1172

Colette was a Belgian gun manufacturer that made this interesting parlor pistol. It used a rocketball type of cartridge, in which the powder and primer were encased in the hollow base of the bullet to make a caseless cartridge. The gravity pistol was named for its gravity feed mechanism and its 20-round capacity. Because of the very limited powder capacity of this type of cartridge, these pistols were made solely for sporting and recreational use, without an attempt at military adoption.