There is a small, slender yew crossbow in the National Museum of Ireland. It is dead straight but damaged slightly at the centre, so it has been used. It dates to between 10th and 12th century and is exactly like a mini ELB. I am interested in making a replica. Here's the interesting part, it doesn't have any sapwood but the back ring is intact from the photos I've seen. Unfortunately I can't get permission to share them. I contacted the museum who pulled it from the case to have a good look. They think the sapwood was deliberately removed, probably during manufacture. So, a yew short bow, highly stressed showing no set but with the sapwood removed and the ring chased with a rounded belly. If it had sapwood I would just think it was really carefully made and wish I was that skilled, but would a heartwood yew bow survive in use? What would you think?