Wow thanks for all the comments guys,I really appreciate the feedback and kind remarks. Your all too nice.
To Koan; I induced reflex into it prior to tillering with the flipped tips resting 1 7'8" above the handle at the back. It took about 1- 1/2" set and came in a little underweight so I piked it one inch at each end and heat treated it back into 1- 1/2" reflex then adjusted tiller and it ended up with the flipped tips about 1/2" above handle.
To Higheagle; Yes that is the natural back under the bark, sapwood with some very small bits of cambium left on. Sapwood thickness can vary on buckthorn and on this stave it was pretty thick and there is only a small amount of heartwood left on the belly side. I've chased rings on this wood before and left more heartwood than sap and it seems to help the bow hold more reflex although a mostly sapwood bow is fine. Really tough to chase rings on this stuff though. Hope your able to find some in your area Chuck.