Many years ago (the 80's to be more precise) a man named Vern Juenke created the first inductive projectile concentricity checker.

A good history of that is available at the Bullet Inspectors web site. Bullet Inspector Juenke Machine History

A lot has been speculated regarding the machines including how and why they work. Some of it fact and some of it fiction (ultrasonic anyone???) but regardless of how they work, one thing for sure is that they do work.

Unfortunatly those machines are not presently being made for 2 reasons. The fact that Vern has long since passed from this world and the fact that the electrical components he used and the electrical behaviour the machines operation depends on are no longer available.

Reinventing the wheel. Yes it can be done.

Knowing that I would never get my hands on a real Juenke Machine I set about to build my own. That was some time ago (2012 to be somewhat precise).

Rather that recreating the original machine I worked upwards from the basic electromagnetic principles behind the original machine and developed my own.

By 2014 I had a viable machine suitable for my own use but I knew it could be better.

By 2015 I had developed an even better one still for my own use.

2017 saw me attempt to put together a design that could be economically produced and was easy enough to be used by anyone. Initial testing by some friends indicated that manually turning the projectiles wasn't viable and the accuracy was also not high enough to give a good reading for larger calibre projectiles. Because of that the idea of commercialising it was scrapped.

Fast forward a couple of years to 2019 and quite a lot has changed:

• 3D printers are all the rage and cheap enough to use to produce the mechanisms needed to rotate the projectile automatically.
• I implemented an improvement to the circuitry that effectively doubled the sensitivity and made the units suitable for measuring up to .338
• I was able to better manage air movement within the case to increase temperature stability and thus sensor stability.

Jan 2020 saw me able to implement the enhhancements and thus complete a number of the "Prototype" units for sale.

May 2020 has seen the first 4 "Production" completed and available for sale.

This timeline has been captured somewhat on the Mr BCRC youtube channel https://www.youtube.com/c/MrBCRC