The first targets for the Howa look promising. I was surprised that the Speer bullets did that well.
The Hornady 140s must have been the ELD-Ms. They seem to shoot great in any 6.5mm.
The SSTs don't seem to work as well in the Howa barrel.
Things may have gone south with the second target. Normally the Hornady 123 ELD-M bullets perform pretty well.
Looks like you found something that works for the Ruger on the second target. I am surprised the SSTs performed so well.
The Ruger seems to like them and the 123 ELD-Ms. From what I can see, I would say the Ruger barrel will prefer lighter bullets.
Every barrel has its own preferences. Only tests like this will give you the data to determine what the barrels really like.