1-9 won't stabilize the 77 grain and heavier bullets with the sexy BC you need for F-Class. I would call Jim at NSS and order a Criterion or Shilen 26" bull barrel with a 1-7 twist. I would tell him you are looking to shoot a 77 grain SMK or heavier so you can get a good throat length for the heavier bullets. Faster twist, heavier bullets, and higher BC's should help push your scores up.
Another question have you looked at your set up? Good bags, front rests or bipods can add points.