My short attention span tonight wont allow me to read through all of the above posts, but I'll pitch in my two cents anyways and hope that it hasn't been addressed.

I'd assume that trajectory has something to do with the whole deal. Bows, for instance, have a high trajectory while guns, for instance, are generally aim and shoot. So as where Johnny standing behind jimmy with a bow might be able to land an arrow in X region, Johnny wouldn't be able to pull the same stunt with a gun without extensive training and practice.