The Juenke machine ($790 current price and year wait)is an interesting machine that has ardent believers and other guys that swear it is BS. do not own one, but have been borrowing one to test bullets and cases. The guy that I borrow from has been one of the most dominant 1K shooters the last 5 years and won top shooter in at least one class for 3 yrs at least and overall twice. He is an ardent disciple of the Juenke to sort bullets and cases. In fact he is one of the most meticulous reloaders I have ever seen. He sorts 1000 cases to the .1 grain, preps, fireforms, then spins on Juenke. Bullets are weighed, sorted, and spun on Juenke.
His testing has proven at least to him, that it is valid. Also, it quickly shows that the JLK and Carteruccio bullets are by far the most consistent on the market at this time. In his testing, the JLK is so consistent that he only gets two main groups out of a 1000 with a handfull of deviations. However the theory is that those deviant bullets are the ones that mess a group up. Bergers on the other hand end up with about 6-8 main groups.
Surprising use is to sort cases. I have done it and proven that it will show cases that tend to throw a bullet out of a group from the others. Just spun my last batch of cases last night. However, they must be fireformed and NOT resized. Your dominant 1k shooters number each case and know which round landed out of a group so it is easy for them to retest that lot of cases and they normally just throw out the bad case. So it is easy to spin the cases on a Juenke and see any deviation from the group norm which has been shown to be accurate.
Vern Juenke has a year wait and is building 50 machines now for 50 cal shooters so good luck if you want one. best bet is to find one and see if you think it works for you before spending the money, $790 current price and going up all the time.
BH