I dont know if Im quailified to have my say here, as I dont as yet have FAC, but I would say, its more a question of what your shooting, and why
if your shooting from a pest control point of view, at rabbits, a shot to the upper body is In my eye's, as good as a head shot, its going to put the rabbit down, unlike an air rifle, where a head shot is needed, Ive been rimfire .22 shooting (under supervison) and quite a few of the shots were body shots at ranges between 30yds to 70yds,
if however the shooting of quarry was for re sale (butchers etc) then on rabbits I could understand the need for