You could of also possibly hit that buck high and that could be why u aint got much blood. Above the lungs but below the spine is a void area of just meat. But ive shot deer with a 30.06 and had weak trails at first so maybe that cud be the case with ur buck! Use a roll of TP to trail him. Whenever u find a speck of blood or his runnin track drop a small piece of TP on the ground. This helps in tracking and lets u know the clear direction of his travel. If he is hit hard he will typically run in a straight line. Good luck!