Test: 33.95 gr JSB pellets, Daystate Red WOLF .25CAL, Helliboard at PWR 9, caps at 70.2v. 50 yds, Harrell's tuner. All settings left alone except for the tuner.
Observations: Starting at 100 on the tuner, adjustments were made in 5 unit increments. As the values increased, the resulting pellet shot pattern changed slightly with each 5 unit modification. The pellet pattern started out moving mostly horizontal in group width. As the tuner units were increased, the horizontal pattern started to tighten, becoming a vertical pellet pattern. As the tuner units were increased, the pellet 5 shot patterns began to revert back to the mostly horizontal pattern varying in width.
Once the pellet pattern was horizontal, 1 unit incremental adjustments were made and the vertical pattern began to shrink until the pellets were hole-in-hole.
During two different test days, to repeat the results, a 6 unit adjustment had to be made. Tuners appear to be very sensitive to numerous factors. More discovery work needed.