A Barrel Straightness Measurement System for Medium Caliber

Gun barrel straightness is a critical manufacturing requirement for all calibers. Precision laser-based photo diode systems have been developed and perfected for quick and accurate centerline straightness measurement of large caliber smooth bore barrels. However, an equivalent system for medium caliber does not exist. A reduced caliber not only means smaller mechanical and electrical components, but also that barrel rifling will be present. This presents an added challenge to the centerline measurement. Kregel Technical Services, Inc and the U.S. Army Research Laboratory (ARL) have worked together to develop a fast and accurate system for measuring a rifled medium caliber barrel centerline. This report describes the measurement system and demonstrates how it works on 20-mm M197 test barrels.