I also zero my hunting rifles for Maximum Point Blank Range based on average/estimated "vitals zone" target size. Here is a very simplified reference that may be useful to you. http://www.loadammo.com/Topics/February02.htm
My reloading software from RCBS has the MPBR feature in the External Ballistics Calculator tool of the software.
The US Army uses these principles in their "Battle Sight Zero" techniques for their basic rifle marksmanship program, taught to all soldiers. If you zero the rifle for "Battle Sight Zero", based on the average size of the human torso, no adjustments in elevation are needed in the heat of the "fire fight", out to 300 meters.
Using MPBR or "Battle Sight Zero", you will not win at the local NRA Highpower match, but it will put "meat on the table"! Coyotes or Insurgents!
Redhound80