Difference in Milled & Stamped Receivers

The difference between a milled metal receiver and a stamped metal receiver on a firearm affects the quality, cost and reliability of the firearm. A milled metal piece is shaped out of a solid piece of steel; a stamped metal part is stamped, or hit with a press, and folded into shape out of a precut, flat piece of steel. Milled parts are manufactured for greater accuracy and therefore create more trouble-free firearms.

  1. Firearm Receiver

    • The receiver on a firearm is the area directly behind the breech, which is the chamber where the ammunition fires. The receiver receives the ammunition from a magazine or clip; the gun's bolt then slides through the receiver and loads the bullet into the firing chamber and closes the breech. This metallic frame situated behind the breech of a gun is responsible for reliable operation of the firearm and can be a point at which a firearm jambs.

    Milled Receivers

    • In its simplest form, milling refers to the process by which a solid metal part is converted into a custom-shaped, engineered part. On a standard milling machine, the milling cutting tool, or bit, stays stationary, and the metal part moves across a table in three dimensions. CNC milling machines feature computer-operated bits and tables, and both the bit and the table move to create parts while controlled by the computer's graphic design software. As a result, the length, width, height and overall shape of the finished piece is controlled within tight tolerances.

    Stamped Receivers

    • Stamped parts are formed from a flat steel sheet. The steel is die-cut in one application. The preshaped piece is placed into another machine that slams the metal part between two dies that fold the steel into an engineered shape. Stamped receivers can't be created to the same tolerances as a milled part. If the stamping die becomes worn, or if the metal part is slightly out of place, the resulting variances in the manufactured receiver may cause problems in the assembled firearm.

    Why Two Versions?

    • When two versions of the same firearm are present in the marketplace, the firearm was likely mass produced at a certain point in its history. The Russian AK-47 has a number of versions and was manufactured across the Soviet-European bloc during the years following World War II. The highly reliable and useful fully milled firearm was sent into mass production. As a way of saving costs and increasing the rate at which the firearm was manufactured, the receiver was converted from a high-quality milled part to a stamped steel part.