I've had similar experiences as others here have already mentioned. Keeping the moisture down during the build has been, to me, the most critical part. I've had great luck "fire hardening" wide, thin hickory bows as well. I don't pay much attention to the science of it, but the creosote in the smoke probably has something to do with it. Not sure, I just know it's worked well for me and the bows hold reflex even in higher humidity. Build dry, heat treat/fire harden, seal with more coats of finish than other species and you should be good to go. They'll still lose a little cast on the worst summer days, but they spring right back to life once they dry out.