Swipa, Are your ash shafts already cut to length? If not, leave them long and cut them back till they fly right. The ash shafts i have used needed to be a little bit under spined for my draw wieght to fly good. Ash shafts seem to be a little "rubbery" for lack of a better word, meaning they seem to bend easier than cedar but are not as brittle and will not break as easy. I have made and shot about four dozen ash arrows. They will bend but are easy to straighten. I don't know anything about birch. If you end up liking ash shoot me a PM, I have 600-700 shafts laying around the shop and me my kids and my grandchildren to come can't use that many shafts !!!