Ok so I updated my data from last time.
Im shooting JSB exact 25.4g pellets
My first string has my vms, HS and HT at factory setting. The rest of my strings have my vms at 5.5 ccw, so my valve is wide open.
The second and third data table lists are with the original spring and have the HS=3CW, HT=0,
The new 12.5lb hammer spring data (last two on table and highest two graph trends) have the following:
12lb spring 1 (yellow on graph) with 5.5 across the board. 12b spring 2 (red on graph) has the HS=3.5CW, HT=5.5CW and vms=5.5CCW
Its clear that my new 12.5 lb hammer spring is set to high according to the decending velocities. But I managed to level it off a bit on the 1st four shots of the second attempt compared to the first (red vs yellow.) when I reduced the HS by 2 turns.
Im guessing I need to try reducing the hammer in 1/4 turn increments to see if i can have a flat first 8 shot string, which I can live with..