It broke while exercising the limb just shy of 22 inches. I never drew it past 46#. It broke just below the last knot cluster where it seemed to be stiffest. There was no warning, just a violent explosion and that was that. Didn't hit my head, but I was glad I had the safety glasses on all the same. I think either:
1. the stave was doomed from the start, or
2. it was too thin just shy of the knot causing stress that the wavy grain could not take. the kid bow from the same tree broke in almost the exact same way (diagonal fracture just below a knot).
I wonder if heat treating made the wood more brittle.
I have one more stave roughed out from this tree that is much cleaner, both on the back and knot-wise. It won't hurt to try again.