I will share a story with all of you in hopes it helps the OP with his question.
Several years ago, I purchased a good F-Class rifle.
It was a 284 and after a fashion, I re-barreled it to a dasher. Dan Dowling chambered it with his proven 104 FB reamer.... I believe it is the same reamer used to chamber Mr Schatz's barrel..... the one that put the dasher on the map.
This gun shot amazingly well, you could test and see little stuff at distance. It really was awesome. I did not know how awesome it was until I sold it and bought the latest flavor of the day.
Deep creek tracker stock (Green and black Wheeler paint scheme)
Panda Action with two bolts
B&A trigger
Krieger barrels
Kelbly's rings
Ezell tuner
March HM 10-60
I won more than my share of IBS (local) 600 yard matches with it and after it had about 850-900 rounds on the barrel, I decided to get another barrel chambered and ready to go. I also had a 300 WSM barrel chambered for it at the same time.
I decided to take all my loading malarkey to the range and develop a load there in one day, it proved to be a dandy idea. I actually think
@BoydAllen made the suggestion and about the hundredth time he told me that, I decided to try it.
So, with a whole day to play, I set up my gear at the range and went to work. Having already been successful with that barrel/chamber combo, I focused on that combination....... and it worked. It was about 32grains of H4895 with a Vapor Trail Bullet as I recall. After getting seating, powder, bushing, mandrel, and primer combination sorted out, I adjusted the tuner one mark in each direction to see if I could see any improvement. Nope, tuner set at zero where it was during tuning, was the best setting.
I screw the tuner all the way in and back it off a half a turn, if zero in close, I turn it to zero and leave it alone until I need it. If zero is less than 1/2 turn out, I give the tuner another full spin and bring zero to the top. I always tune with zero at the top dead center.
I shot several groups at 600 and the gun was on point, shooting sub 2" groups at 600 is good, actually really good here in Western Colorado.
Mike had explained his "Tuner Test" to me, so I cleaned the barrel and shot Mike's tuner test at 600 yards.
It did not look as pretty as the 100 yard test he uses as an example but after sending him pics, the pattern was still there.
Satisfied with my results, I loaded up all my "stuff" and headed to the 100/200 short range BR range 1/4 mile down the road.
I had just started shooting a PPC and thought they sucked!!!! What a POS! Couldn't keep that thing in tune to save my backside. So, I wanted to see if my hot shooting dasher could group at 100/200 like it does at 600 yards.
I set up all my gear and loaded some test ammo. Same rest, rifle, everything the same.
I shot a very embarrassing target. It fully looked like a bucket of yuck blew up on it. Awful indeed!!!
So, I set up to retune (powder, seating, etc.) at 100........ but wait, I have a tuner......
I loaded up the previous load and shot a three shot group, moved the tuner one mark and shot another group, so on and so forth, basically Mike's tuner test all over again.
I found a beautiful tune...... very competitive indeed. I moved the target frame to 200 yards and tried it again. The tune was good.
So I cleaned the barrel about the zillionth time for the day and loaded up more ammo. I then picked up all my gear and headed back to the 600 yard range. Knowing in my heart, I found the GOOD!
After setting up all the gear and relaxing for a few minutes knowing this could be epic, I worked up the courage to bring my best self to the line and shoot groups that would blow the doors off all my previous accomplishments.
Epic alright, epic failure.
I shot a very ugly target, tried it again, yep..... UGLY.
Turned the tuner back to the good 600 yard mark......... knotted up. Shot it again, a dandy group.
So, fast forward a couple of months, I had won a couple of IBS matches with that barrel and life was good. I attended a short range BR match at the local club and shot my usual Poorly.... me and my PPC were not friends. This was the year that the NBRSA had pooped in somebody's cheerios and none of the clubs in the region were shooting registered matches ( I actually do not know the full story but just know the match I attended was not a registered match and it normally would have been).
After my first days poor performance, I asked the Match Director ( Tom Stiner) if I could shoot my (totally out of class) dasher in the HV match on Sunday. He said, and I quote "You better, I am tired of hearing about that *&^%$ dasher!" "This is not a registered match anyway, see you and that dasher in the morning!"
Happy as a lark, I went home and preloaded some ammo. Grabbed my stuff and loaded the truck for the match the following morning.
The following morning, I reviewed my notes in my TUNER notebook (for me, this notebook is super important), and made the adjustment I had worked out previously. The first target at 200 showed it was good. I made some errors and got caught a few times, but I did come out in first place...... I absolutely had the smallest agg shot that morning. Out of class and all that, but the tune held just fine. Just for giggles, after I shot my last record target at 200, I shot a group on my last sighter target with the 600 yard setting on the tuner and it was pure yuck.
After lunch, we moved the target frames to 100 yards and got busy.
My 100 yard performance was not near as good as my 200 yard performance was, but it was good enough that I placed in the top 3 or 4 for the grand.
Based on my experience, I shoot Mike's Tuner Test at the distance I intend to compete at. Anything less, is just being lazy or frugal or both. I remind myself all the time, there is a place for lazy and frugal, but it ain't in benchrest.
I hope this helps
CW
Edit
I have had tuners save the day plenty of times. Most every barrel I have chambered is threaded for a tuner. They work, if you are willing to put in the effort to learn how to use them.
CW