The Deathclaw weak spot in Fallout 76 is its belly/underbelly , and for weak-spot challenges you generally need the killing blow to land there for it to count.

Main weak spot: the belly

  • Deathclaws have tough, plated heads and backs, so shooting the head is not a real weak spot in 76. Their skull is effectively as resistant as the rest of the body.
  • The true weak spot is the soft belly/underbelly , which takes noticeably higher damage when you connect hits there.
  • Community discussions around the “kill a Deathclaw using its weak spot” challenge consistently confirm that the game checks for a final hit to the belly for the credit to trigger.

How to reliably hit the weak spot

  • Use VATS to target the torso/belly when the Deathclaw rears up or charges; some players report the challenge only counting when they ensured manual selection of that area rather than random torso hits.
  • Fighting on uneven terrain or slopes makes it easier to see and hit the underbelly instead of wasting shots on the head or back plates.
  • Fast melee or automatic weapons help “spray” the gut area when it is close, improving the chances the killing blow lands on the weak spot for challenge completion.

Extra tips for the challenge

  • If the challenge is not registering, players report success by:
    • Switching servers to avoid lag or desync affecting where the game thinks the hit landed.
* Avoiding VATS critical shots for the final blow, as some anecdotes suggest crits can bug the trigger for this specific objective.
  • You do not have to be in a specific place (like Burning Springs); any Deathclaw encounter works, as long as the final hit is to the belly.

TL;DR: Aim for the underbelly , not the head—make sure the last hit connects with the gut, and the weak-spot kill should register.

Information gathered from public forums or data available on the internet and portrayed here.