Right before exiting the vault, after being in a deep, cryogenically induced sleep for over 200 years, you'll most likely come across a gun that's locked in case on a wall. You can't unlock this case early on in the game since it requires you to have the Perk that allows unlocking of Master locks.
There is a workaround though. Apparently Dogmeat defies the rules of locks, cases and also gravity, and can fetch the Cryolater for you. You'll obviously need Dogmeat first, so you'll first need to make your way to Red Rocket station that's right outside of Sanctuary.
Once you have Dogmeat, make your way back to Vault 111 and head to the office that houses the Cryolator on the wall. All you need to do then is give Dogmeat the following commands. Talk, then Fetch, and then Items. Dogmeat will then magically grab the Cryolator for you.
Congratulations, you now have one of the better guns (assuming you're speced for it) early enough in the game to do some serious damage.
[Thanks Patricia via Kotaku]
