WordNet (r) 3.0 (2006):

crack shot
    n 1: someone skilled in shooting [syn: marksman,
         sharpshooter, crack shot]

Moby Thesaurus II by Grady Ward, 1.0:

56 Moby Thesaurus words for "crack shot":
   Admirable Crichton, Nimrod, adept, archer, artilleryman, artisan,
   artist, attache, authority, bowman, cannoneer, carabineer,
   connaisseur, connoisseur, consultant, cordon bleu, craftsman,
   dead shot, deadeye, diplomat, diplomatist, elder statesman,
   experienced hand, expert, expert consultant, good shot, graduate,
   gun, gunman, gunner, handy man, hunter, journeyman, marksman,
   markswoman, musketeer, no slouch, politician, pro, professional,
   professor, proficient, rifleman, savant, shark, sharp,
   sharpshooter, shooter, shot, sniper, statesman, targetshooter,
   technical adviser, technician, toxophilite, trapshooter