|From Limitless: The Assassination Of Eddie Mora|
Superheroes don't tend to use firearms, but often their foes do - highly paid hitmen, for example. So gamesmasters looking for gameable details on the latest sniper rifles could do worse than checking out this list from Osprey publishing.
Lower-end villains tend to use whatever's to hand when brawling with the heroes, and good old Oddee has a list of "crazy" improvised weaponry (although the woman who used her baby in this manner isn't probably something you want to emulate at the table!)
Both these lists are also useful for other contemporary genres as well as superhero RPGs; espionage, crime investigation, and conspiracy games, for instance.