Doubt you'll beat the White Oak Precision with a top of the line barrel just don't confuse them with White Oak Armament. Same company but they use Wilson blanks from what I understand. Not a bad choice but not the best.
I've bought or built several AR's, a few were accuracy minded and the most accurate barrel I've shot was from Krieger. I sold it due to weight and it's super tight chamber.
I now have 2 Noveske barrels that shoot half to 3/4 MOA which is all I need.
Another sleeper though is a BM Varminter, I know of one that shot under 1/2 MOA with cheap reman ammo.
Most varmint type AR's will shoot better than most people can. For 300 yards, you won't need heavy bullets so a 1/9 twist would be ok but I'd go at least 1/8. Stay away from billet hype, you won't get any better accuracy over forged receivers. It might look cool but they are heavier and 3 times the price.
