I prefer stick powders to the ball powder I have used. I bought kegs of AA2520 when it was cheap, it shoots well but it leaves lots of residue in the gas system and I have experienced "settling" at long range.
When I shot AA2520 out to 300 yards but used well characterized long range loads with stick powders, I got wild shots for the first two sighters and unpredictable shots for the next two to three rounds. It takes time for the point of impact to settle. This is not acceptable in a rifle match. I never had had this issue going from stick to stick.
In my opinion, IMR 4895 is the “standard” for the 308 in gas guns. You either go faster or a bit slower. I would stay within the same guidelines that are used in M1a’s, that is nothing faster than IMR 3031 and nothing slower than IMR 4064.
IMR 4895/AA2495/H4895 are close copies of each other, AA2495 gives the same pressure curve and is a copy of IMR 4895, but stupidly Accurate Arms gave it a different name and that confuses everyone. Buy by price.
I can recommend IMR 4064 but charges have to be weighed as it does not throw well. Varget is an outstanding powder, little slower than IMR 4895.
All things equal, faster powders are better than slower in gas guns.
A standard match load for decades was a 168 SMK 41.5 grains IMR 4895 LC cases , use CCI #34’s, OAL LT 2.800”
Since your barrel is a Kreiger barrel you must cut your loads as Kreiger barrels are tight. Try 40.5 grains IMR 4895/AA2495/H4895 and carefully work your way up.