He's dead. go back to where you last found blood and watch for buzzards in a tree or as you walk around they will all take off if you get close to them. I can't image the buck going much farther. I would think a chest shot would have done him in. I shot this buck with a 300mag, left a huge hole, blood everywhere and he still ran 100 yards. I was real suprised.
http://i92.photobucket.com/albums/l16/texas8point/rusty1.jpg