The GP100 is a family/line of double action five-shot (.44 Special), six-shot (.357 Magnum, .38 Special, & 10mm Auto), seven-shot (.357 Magnum & .327 Federal Magnum), or ten-shot (.22 Long Rifle) revolvers made by Sturm, Ruger & Co., manufactured in the United States. Since its introduction, it has been produced with a number of variations including various barrel lengths and profiles, fixed or adjustable sights, and in blued carbon steel or stainless steel.