Guide to find location of the Legendary gun weapons of Dying Light: The Beast.

Legendary SMG: The Needle

From the Camping Tower you find in your first outside mission, go down the river in your left and find the Park Ranger Station.

Find the green container and jump inside it from it's little door on top of it.

Connect the cable to the little station next to the Park Ranger Station and it's garage door with the text "Don't Open, Dead Inside" will open.

Clear Zombies and you will find the Legendary SMG: The Needle on a table inside the door with Lockpick (Hard).

Legendary Grenade Launcher

After enabling the Grenade Launcher skill, you can craft it in your upgrade station in the safe places you sleep and store your stuff in.