would adding a bit more pre-load and lightening the hammer flatten out the string?
I'm wondering the same thing. I might try another 1/4 turn on the HS to maybe tighten it up a bit.
We should ask Bob or Lloyd to run the numbers for this rifle on their spreadsheet to see if they have any tuning advice....
I was told by many people on this forum that I should be able to get a good 60+fpe and 80+fpe tune with a stock barrel , t-port, and WAR valve. I am still waiting for my WAR valve so I cannot confirm this.
With a 25 inch barrel increasing efficiency and the tube extension providing more air, I would have hoped for at least 12 shots @65fpe within 2% and 18+ within 3%.
It looks like you are close to this.