I agree with your method. Except I fire a three round group at 50 adjust and fire at 100. Fire again. Usually I am right where I want to be. Between 1 and 1.5 high at 100 will put you right close at 200 and with my 270 about 6 inches low at 300. Also I don't aim for the bullseye I aim for the sharp point above the bullseye makes for a more precise point of aim.