Most clay pigeon targets consist of petroleum-based hot pitch and milled limestone. These two ingredients are hot-molded together. Limestone makes up 60 to 80 percent of the target; the remainder is pitch.
Newer pigeon designs are made from nontoxic ingredients including plaster, calcium bicarbonate, fly ash and heavy spar. These are not biodegradable, but they are not as harmful to the environment as traditional clay pigeon designs.
Patents for biodegradable "clay" pigeons include simple, edible ingredients, such as sugar, birdseed and water. Grain is a possible substitute for birdseed.
Composition of clay pigeons must be firm enough for the targets to remain intact when they are shipped, stored, loaded and thrown into the air. The targets, however, must also be fragile enough to break when they are struck by a small number of pellets from a shotgun blast.