30” barrel with 42.7gn of H4350 I get 2900 with Berger 140 hybrids so with a26” barrel you should be at about 2800. I would start around 41.5gn and work up. I went up to 43gn and stopped there because I felt a little sticky bolt lift on a couple rounds.
I purchased some Hornady 140eld ammo that was on sale a few years ago and got 2900fps out of it. I was surprised to get that kind of speed out of factory ammo I could tell it was hot by the felt recoil so I chronographed it.