Benn's marksmanship should contrast with Yasopp's, so there's a noticeable difference between them. For example, Brook is a fencing-style swordsman who uses delayed-effect slashes, while Zoro is a physical Mighty Blade-type swordsman who unleashes flying slashes.
Yasopp's epithet is "Chaser," and he's the sniper of his crew. Luffy praised his accuracy when mentioning him to Usopp in Chapter 25. Therefore, it follows that Benn's marksmanship will be more focused on power, such as ACOC-infused bullets.