It is Claro Walnut. He specializes in american walnut generally. You can check it out at wattswalnut. com
I have put about 300 rounds through the HK so far and it is a beast. I can actually shoot it better than I could my Kimber TLE (which makes no sense to me). It will eat any kind of ammo period. I enjoy it emmensely.
The Ruger is a .270 and I havn't shot it since it has been restocked and scoped.