A thick, square sectioned hickory longbow sure sounds like a recipe for handshock to me.
And as Marc says, hickory does not chrysal too readily unless it is very seriously overstressed in compression and I would expect a hickory self bow to be quite slender as compared to a same draw weight long bow in Yew, Ash or Elm.
Rod.
(Shooting an old home made Hickory self bow at the NFAS 3D Nationals this coming weekend, but a PV, not an LB).