Graham,
Please see attached.
Spear tip is actually three small triangles. From the break (top of hand) to tip its exactly 8.72mm and width of spear tines is 1.96mm. Bottom of last tine to tip is 5.75mm In my example the tines on side closest to head are not defined because of the plating process.
Sorry all I have is an old scanner so you'll have to enlarge.
Scan0007.jpg
Clay