Remember this is 22 Rimfire. It is basically 1900s technology improved with slightly better aerodynamics. The bullet is a high BC lead slug. It is never going to be as accurate at 300 as a center fire PRS round.
All this is trying to say keep your expectations in check. There is Black Magic involved in long range 22LR shooting. We each will have our own opinions of how to get there.
Get good ammo, a great Barrel, a really good scope and a great rest and shoot a lot of rounds and you will find happiness, at least I do.