Red Faction

Note: All weapon-related trophies count across all saves. If you want you can make a save near enemies, kill them, reload the save and repeat the process for every trophy.

The Rail Driver is one of the late-game weapons and can only be acquired from Masako's mercenaries. The scope of the Rail Driver allows you to see through walls and, more importantly, allows you to shoot enemies through walls. It's a highly recommended weapon so you should get this naturally.