KaptainAccuracy stats is (shots hit)/(shots fired), it doesn't have anything to do with damage. You can get an accuracy of more than 100% with the flaregun (and flamethrowers, but you don't see that happening often because you tend to spam the flamethrower a lot) because you only shoot once and set the other player on fire, and every tick of afterburn is another "hit".
What about the Boston Basher?