In the Hospital section of Cronos: The New Dawn, there is an optional puzzle you can complete to nab a new weapon. This comes during the time jump section of the hospital. Mild spoilers ahead.
During the time jump sequence in the hospital, where you must help a trapped Weronika who is stuck in an elevator. To the right of the elevators, you can find the Traveler’s safe room, which is also the hospital chapel. There is a locked backroom containing the Mace JER-5120, the double-barrel shotgun. In order to open the backdoor, you will need to gather two chalices in the hospital, one in the director’s office, and another in a ward locked behind a key card.
Director’s Office Chalice
Advance through the main mission in the hospital area until you get the first chemical compound and the doctor’s key card that opens locked areas. This will bring you to the Administration section of the hospital, and you want to go into this large room with large red fleshy tentacles going everywhere. There is a small side path you can walk down, leading to you ducking under some flesh.