Ok so I found out the issue, if you're using this as a charecter skin the arms are spaced like that perfectly, but the charecter model of a mob skeleton has a 2x2x12 surface area which means you have to move the 4 sides together and then shift them 1 square up, so they're contiguous with the jaw of the skull. it's an easy fix, and looks awesome on Mobs, great skin dude.

Looks cool, but doesn't work when used for a mob Skeleton skin in costom packs, will investigate to see why, but I thike it a lot more than the default Skeleton Mob skin.