The bullet drop at 300 yards is going to be totally dependent on what distance you have the rifle zeroed for and what bullet weight and configuration you are shooting. In other words, if the rifle is zeroed for 100,200, or 300 yards the drop will be different. With respect to bullet weight a 40 grain is going to drop less than a 60 grain bullet. So the answer is not a simple one.
I might highly suggest that you look at the ballistcs calculator available at:
If zero at 50 yds = 5.1 inches
If zero at 100 yds = 7.5 inches
If zero at 150 yds = 6.7 inches
If zero at 200 yds = 4.9 inches
If zero at 250 yds = 2.7 inches
This is an extremely handy tool to easily use to more fully understand the flight of your bullet and to easily compare different calibers and bullet weights. Spend some time you will enjoy it. You will also find that the height ofthe sight or scope above the bore changes the trajectory of the sight line.