Direct Indicating the Bore...

[Spotshooter]

Dial in the grooves at one point, then the second making your adjustments just like you would with a rod, but watching the needle when it drops into the land.. watch out for using heavy oil (clean the bore) as it can throw you off.

Check you “rod repeatability”... dial it in once perfectly, then pull it out, spin it a bit and then see if it’s still perfect.

 

[tobnpr]

^^
Sure is.
How is the stylus held in the fixture?

 

[tobnpr]

Check you “rod repeatability”... dial it in once perfectly, then pull it out, spin it a bit and then see if it’s still perfect.

I couldn't get good repeatability with range rods when I first tried them; I get best results with the grizzly rods.
With them, I hang a light weight (barrel stub) on the rod just behind the indicator so that whatever tolerance stacking exists is largely mitigated.