And of course the other point is that (depending on the discipline) rifle shooting may be multi positional. You could be shooting prone, kneeling, perhaps bent over slightly (to take advantage of a rest in the field), or indeed stood up on your back legs. The ideal length of pull would be different for each.

Still wondering why it's under general airgun. I wonder if Rigbys' would build me an Airsporter? Perhaps they could do in in .25!!!