COLLECTABLE and
MISSABLEAttachments for guns are scattered throughout Raccoon City, but are mostly reserved for puzzles. Eventually you will come across a gate holding back some zombies, which will later be broken down by said zombies letting you get past. Shoot your way through them, and before you make it to the Donut Shop, hang a right to a set of stairs, and take a left. You will reach a door to a room with a safe inside.
The combination for the safe is the following:
Left 9
Right 3
Left 7
Inside will be a Laser Sight for you G19 Handgun, combine it with your handgun and you will get this trophy.