Thanks Gene not being one who believes there any stupid questions why not ask what comes to mind to those you trust and thank you for your input. I have used the steady rest approach rifle shoots good. Through the headstock dialing in both ends using guage pins rifles shoot good. Now time to try something I have not yet tried dialing in the throat. I don't have a long reach indicator I can get one and that's what prompted my question. In my own head by dialing it in 360 I could also use the tail stock to push the reamer straight in after being drilled and bored. I have always strived to reach perfection with everything I do. So I have always picked the minds of those who have already reached the place I want to take myself too.
The problem with using the tailstock (though it may not be a problem) is that any misalignment between tailstock and spindle persists. You can put something in the spindle and dial it to zero runout, but any difference between the spindle center of rotation and the tailstock is still there. No amount of workholding adjustment will ever change that (the work must rotate on the same center as the spindle). Which leads to the tailstock. The tailstock might be right in line with the spinde, in which case Bob's your uncle and you're on your merry way. But, most likely your tailstock is not perfectly aligned with your spindle (darnit!) and it's probably high by a thou or two. (mine is several thousandths high). There are some convolutions you can go to - modifying your tailstock, torquing it to a locked position with a torque wrench (not a guarantee - but if it makes you feel good...), or using your headstock, dialed in, to drill and ream a center for tailstock operations. There are also expensive tailstock offset adapters (the astute viewer will note one in the Gordy video...) but they must be offest in distance AND direction to really fix the problem. IMO, most of those 'adjustments' are not worth it. Yep (comin' out of the closet) I use a (JGS) floating reamer holder...
Don't discount your own experience. I've cut chambers in the worst of ways and ended up with shooters (though probably not by benchrest standards), but there are too many variables to nail down for anyone to say "this is the one true way to cut an accurate chamber". A lot of folks claim that, but it's statistically impractical to prove. IMO, you get a barrel, of whatever quality, and things can only go downhill from there. You use technique X or Y to cut the chamber and it shoots or it doesn't - that doesn't prove a thing about technique X or Y - it's that barrel, and your implementation of the technique, and *luck*. You could have the wrong technique entirely, but implement it badly and end up accidentally cutting a perfect chamber. It likely wouldn't ever happen again, but it's possible. The point is, any particular result isn't really proof or indictment of any method - there are just too many variables to score. Chambering theory is just that - theory. If it were established science you would see everyone here agreeing that "XXX" is the only right way to chamber a barrel.
BTW, because you've mentioned my name, I want to note, I'm not an expert. I'm an explorer, just like you. The day I can cut three consecutive barrels that all shoot "teens" I'll let you know (trust me, you won't miss the announcement!),