The gauge system itself dates back to the era of muzzleloading firearms, with the gauge number referring to how many lead balls of that bore diameter weighed one pound. Shotgun shells used to me made from brass casings & paper hulls that were loaded with black power & lead shot. Plastic hulls debuted in the early 1960's with the Federal Cartridge Corporation pioneering a color coding for shotgun shells, specifically designating yellow for 20 gauge shells. Today's shells are non toxic with lead replaced by steel, bismuth, or tungsten. Our 20 gauge knobs come in several varieties of yellow, or whatever color you want!
