If you going out to 300 yards do yourself a favor and take Yanus' advice and go with at least a 4X12X40. You can buy a Burris, Nikon, or Leupold for a reasonable price. $200 to $300. Stay clear of the lower end optics, it will save you money in the long-run. Believe me, it cost me a bunch of money before I came to this conclusion.
God, Family, Guns, in that order.