Beckman wins this, but solely on reputation. We only saw him hit a nobody with his rifle and point his rifle at Kizaru. We know that he's fast and can jump very high. Haki too. Maybe he can even fire bullets coated in Haki. There would be no point in pointing his rifle to Kizaru otherwise.
Well, if Ben Beckman is a first mate of Shnaks, then I can't see how he won't be able to be at least around Marco in terms of stregth or maybe even stronger as we can assume that the biggest stregth of WB crew was WB himself.
Anyways, Beckman should take this one with eaze. Blueno isn't an opponent for him.