Home Forums Gear Free Classifieds Internal Concentricity Comparator..."Juenke Machine"

Internal Concentricity Comparator made by Vern Juenke. These are used to test the internal concentricity of a bullet. I have had this unit several years, it still works fine. A shooter can learn a tremendous amount about bullets with these machines. These haven't been made in several years.
Here are a few videos.
https://vimeo.com/manage/videos/895652088
https://vimeo.com/manage/videos/895652457
https://vimeo.com/manage/videos/895652751
First to post "I'll take it" trumps PM's.
$1000 includes shipping to the lower 48.

I used to have one of those. Worked very well. But it doesn’t work on monometal bullets.

Yep, because it measures the "internal" concentricity of lead-cored bullets, which depends on consistent jacket thickness and bullet forming.

But it really works on lead-cores. When I was loaned one by Handloader magazine for a couple years, it answer all sorts of questions--including why one particular batch of a "premium" 165-grain .30-caliber hunting bullet grouped so well in any rifle I tried them in, from the .300 Savage to the .300 Winchester Magnum....

I remember your article on it like, 20 years ago! Really interesting stuff.

It’s a piece of equipment I’ve managed to live without, but there are many who shoot way more than I do that would benefit from it.

Bump

Please. An inquiring mind wants to know. What principles are used to measure such given the presence of what might be a perfectly concentric external jacket?

I'll take it. Check your PM here...

It works on "electromagnetic induction." It creates a magnetic field and rotates the bullet (or case) in it to test how it reacts in the field. I have had one for a long time. Neat little machine.

Thankyou aceball for saving me from feeding my addiction