Greybeard,
depends on the Spike! some, with a plain unmarked head are low carbon. If the head has a small H on it, it is a high carbon spike. These H marked ones, are favored by knife/Hawk makers.
Love the Muley! I make muleys myself and have considered making a double myself.
Would appreciate a peak at the inside of the lock, if you would? always interested in seeing how someone else "Put it together"
if nothing else, its an opportunity to learn more! I'm kinda leaning towards making a Billinghust pattern, double. The lock has a single hammer, with a switching striker.. just to make it more difficult
Thanks for sharing this with us
Respect Always
Metalshaper/Jonathan