Methods for impaction grafting an intramedullary canal of a bone including a first canal portion and a second canal portion spaced along a canal axis. A first tamp may be moved axially within the canal to impaction graft the first canal portion. A second tamp may be mounted to the first tamp in axial sliding relationship and moved axially within the canal relative to the first tamp to impaction graft the second canal portion. The first and second tamps may be locked together in fixed axial relationship to prevent relative axial movement between the first tamp and the second tamp while the first tamp is moved to impaction graft the first canal portion before impaction grafting the first canal portion. The first and second tamps may be unlocked to permit relative axial sliding of the first and second tamps before impaction grafting the second canal portion.