Ash, maple, and laminated birch. I have not problem getting arrow weights in excess of 700gr with any of those materials. My newest laminated birch weighted in at 580gr for bare shafts, I have some maples that wiegh right in the same range and I used to have some ash that weighed 520gr for bare shafts. These are all good shafting material and fairly easy to find. 3 rivers sells the laminated birch and there are a few places that you can get the ash and maple. Look in a copy of TBM magazine there are several of thier sponsers that sell them.