Just get more practice and make sure you are using good ammo. 300 yards is not long range. It's an easy shot if you have practiced enough. The rifle and caliber is capable of much more than that.
Just a point of clarification...300 yards to some is a long shot to others its a walk in the park. By sanctioned shooting sports, most agree 600 yards is midrange and 1k long range. There is also extreme long rang stuff which is another animal.
However, if someone hasn't shot past 100 yards ever, shooting 300 yards is long range to them. I remember being that guy less than 10 years ago.
Another thing to mention, shooting 300 yards from a bench is easier than laying prone on a backpack. Shooting 300 yards standing and unsupported is another animal all together. I've been there too, its NOT easy. Anyone who thinks it is, hasn't done it.