Dave A, DAA's explanation will be well worth getting. Especially for you guys who live in parts of the country where the longer shots may be more common or popular.
I'm a stuck in the mud 200 yard zero kinda guy but I certainly hope that DAA has time to explain what he's doing so that you understand it. I live with holding high for that 300 yard shot, on the very rare day where I'd even begin to consider it. DAve has something else to consider.