Mr.Ulrich, The science behind inductively testing metal structures for discontinuities is well understood and effective. However, not so easy with a machine with the stability and sophistication of the Juenke machine. I know some folks who have Juenke machines and some of them are very happy with them. I would guess that the high cost of them, then and now with the copies, is a reflection on the difficulty in properly tuning them both electronically and mechanically. With the state of the art today, it would be way easier to get the stability and accuracy with either an inductive or a dynamic testing system. Most people who want these systems are convinced that group flyers may be directly connected to discontinuities within the bullet, probably either in brass cladding thickness variations or air bubbles in the brass to lead interface.