Look at it this way, MOA at 100 is 3 inches at 300, add in 6 inches of deflection with a 10 knot wind and your at 9 inches. Factor in mechanics and it would be very easy to completely miss at 300. I have a 270 WSM in the Ruger 77 MKII topped with a Nikon Prostaff 3x9. With the scope at 6x shooting winchester 150 gr pp's I'm on chicken shaped silhouettes at 200 like nobodies business, move past that and the heavy trigger pull puts me low/right just about every time. Shooting my 140 accubond handloads and 130 gr SST's or BT's and the gun is very accurate to 300 meters. The first thing is to get the trigger to a point where it's not a factor, then chronograph that load to find out exactly what it does in your gun. Then you can figure out what the ballistics really are. In my experience the values giving by the manufacturers are rarely what you see in the real world and should only be used as an estimate. Then comes the fun part, practice, practice and practice some more.