Noun
foreshaft (plural foreshafts)
The front, projecting part of an object, especially of an arrow or other projectile, on which the tip is attached
The simple Aleut harpoon consisted of four main parts: the wooden shaft, the bone foreshaft, and the bonehead (tip) with barbs pointed backward. Source: Internet
The barbed head was loosely fitted into the socket of the foreshaft so that when the animal was stabbed, it pulled the head away from the rest of the harpoon. Source: Internet