A professional who examines working parts of guns used in testing ammunition to determine that they are in satisfactory condition to be used for making tests.

• Examines bore, cartridge chamber, firing-pin hole, and other parts related to functional operation of gun, using precision measuring instruments.
• Inspects bore of gun for defects, such as scratches, pits, and corrosion, using illuminated periscope.
• Tests operation of gun for satisfactory action.
• May assist gunsmith in adjusting test arms.