who makes a decent bullet comparator?

[savagedasher]

Using Hornady, you'll need 3 pieces. The insert holder, the caliber specific insert, and what they call the Anvil (on the right) which is a larger flat surface to measure from. To research the prices, try here.
https://www.midwayusa.com/case-gages-and-bullet-comparators/br?cid=8868
View attachment 1021753
You can also get the case insert and can measure the shoulder setback (comparing cases to ones fired in your rifle, which should be expanded to the chamber). View attachment 1021754

Good as it gets for the price. Larry