The G3 is a modular weapon system. Its butt-stock, fore-stock and pistol-grip/fire-control assembly may be changed at will in a variety of configurations. Simple push-pins hold the components in place and removing them will allow the user to remove and replace parts rapidly. The weapon made extensive use of cost-saving pressed and stamped steel components rather than machined parts and spot welding to connect parts. The stamped sheet metal cocking handle tube and receiver are large exposed parts that are prone to deformation from hard impact as they were designed to be relatively thin to save weight. If dented severely or deep enough during field service reliability problems due to internal parts movement impairments can occur that put the rifle out of action and can not be field solved by the user. To determine and correct such situations armorers are trained to employ specially designed “GO” and symmetry gauges and straightening mandrels to fairly quickly repair such problems.