What you have to know is where is the point of impact at the yardage and what the yardage is. You need a range finder and then you have to check your loads at known yardages. Some times those drop charts are right on and some times they are not. The last one I check for my .22-6mm was real close. It was off 1/2 moa at 600 yrds., but that`s 3 inches. You also need to know your wind drift and it helps if you can measure the wind speed. The 7 mag. will shoot alittle flatter and give you alittle more margin for error, but at 400 or 500 yrds. not much. For long range shooting I prefer a scope with target knobs and dial in the elevation. Wind drift is more of an art than elevation so I prefer to use mil dots for windage, but some like to dial that in also. Carry a chart with the moa numbers on the scope for the different yrds. so you can dial them in without doing the math every time. If you not shooting past 500 yrds. you can get by without adjusting the scope and simply hold over, but still check you drop at different yrds. so you know how much to hold over. With a 150 gn. SBT bullet in the .308 if you zero it at 200 yrds. it will be abt. 22 1/2 in low and at 500 it will be about 46 1/3 in low. Do your math and then check it befor you go hunting.
