I have got my 300 WSM shooting great at 500 yards. I have her shooting 3-4 inch five shot groups at 500. I determined the actual velocity is at 3250 fps with the Sierra 155 grain Palma bullet. I add 2 1/2 minutes from 400 yards to 500 yards. The BC on the bullet is suppose to be .450. The ballistic calculator I have been using only gives zeroes out to 500 yards. I am now ready to shoot 600 yards(next step). How many minutes do I need to be dead on at 600 yards. By minutes I mean how high do I need to be at 100 yards so that I am dead on at 600. I am using 100 yards for my reference, but I am leaving my rifle zeroed at 400 yards. I hope my question is not too confusing?? Thanks, Tom.