Bryan
I tune a barrel with the tuner when I first install it, (with my pet load), and will tweak the load with the powder measure if the air gets so dry that the 133 goes south. I have found that in this situation, the tuner will not tighten the Rifle up.
In fact, I have modified a lot of my thoughs about my tuners. One thing I have discovered is you do have to find what ever the ideal burn rate for a combination is. Then, fine tune it with the tuner.
With the combo I shoot, there is a load node at about 28.8 grns, and another at about 30.4. Usually, the 30.4 works best.
I have tried to just stick, say, 29.4 in the case, and tune it with the tuner. Guess what. It doesn't work. Sure, you can get it pretty good, but the combination of finding that ideal powder charge, then tweeking it with the tuner, seems to give the best results.
I have, at matches, kept the Rifle shooting at a competitive level with the tuner, so I will move it if I think it will help. But, once it is set at a setting that the barrel likes. I try to avoid messing with it.
I am about to make a statement that will probably rile a lot of people. But I think that at the level it takes to win in Benchrest now, you cannot tune a barrel well enough with a tuner alone to stay at the top. I think the tuner aids in maximizing the efforts of the more conventional methods.
Oh, and by the way. Having a great barrel and a batch of great bullets makes all of this much easier........jackie