Is there a Concentricity gauge that can not only gauge Concentricity but also can correct it that's worth a poop?
I have both runout gauges pictured below and the Hornady gauge has the ability to straighten the neck. BUT if you need to bend the case neck to reduce neck runout then you have a problem with the case, your sizing die or seating die.
So fix the problem BEFORE you need to bend the neck and find out where the runout is coming from.

Below Redding has a new concentricity gauge that looks interesting and better than the ones I have now.
Redding Offers New Slant-Bed Concentricity Checker
http://bulletin.accurateshooter.com/2020/02/redding-offers-new-slant-bed-concentricity-checker/
