It's hard to get a one hit one kill when the paint don't break. I guess you could turn the Velocity WAY up and maybe sort of play Marksman but when you get sued for injuring someone with a paintball to the eye you will wish you just played with the rest of us.
getting a barrel kit may be in your future then. The have different bore sizes to accommodate the varying sizes of paintballs. chekc this link out. http://www.pbnation.com/showthread.php?t=2218018