Story related and can't be missed.
Wake up in Vault 76 and follow the quest markers to the exit. Be sure to pick up some supplies on your way out and use the overseers terminal for mission update. Upon exiting the vault, the achievement will unlock.
If you played the B.E.T.A and completed the mission, you might be required to create a new character and replay the mission for the achievement to unlock until Bethesda implement a way to get achievements retroactively.
As you exit the vault, on your emidiate right there will be a corpse on the ground. Loot it for a pipe pistol and some ammo. Also as you exit the vault, there will be a couple of stairs in front of you. At the bottom you will find a Responder corpse (Fallout 76 faction) with a machete among other things. Be sure to pick the machete up as melee weapons (as of right now at least) melee weapons are increadibly powerful in Fallout 76 and ammo might be scarce in the beginning.
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