At 300 yards, you will want a bullet with a high bc to help buck the wind. If money is no object, I would try some berger 70 or 75 gr vld's. I got excellent results with varget and n135 with the 75's and n133 with the 70's.

If you want to go cheaper and still great accuracy, I would try the hornady 75 gr a-max. They have a bc of .435. Varget works great for me at around 23.7 grains, and I am right about touching the lands .