When Eliot informs them that these are pirate vessels, Vic and Fisheye prick up their ears. Vic unwraps his rifle from the collection of Hefty bags that he uses to protect it from the salt spray, and detaches the bulky sight so that they can use it as a spyglass. Hiro can't see any reason to pull the sight off the rifle in order to do this, other than the fact that if you don't, it looks like you're drawing a bead on whatever you're looking at.