Spartan.
- AGI 3 + marksman (racial)
- Navy brat +1 AGI + marksman
- police officer +1 AGI + marksman
- military academy marksman
- sniper +1 AGI + marksman
- assassin +1 AGI + marksman
That theoretical character would have AGI 7 (4 dice) and 6 ranks of marksman for a total pool of 10 dice. Now, that character is no good at anything but shooting, but he/she's gonna really make combat suck for someone.
I'd say that that career path doesn't even seem especially contrived from a story/flavor standpoint which is a common failing of min/maxing. Even picking marksman every time could be a character being obsessive about his sniper skills (like a superhero-style sniper).