Or version 1.2, cause that is the last version with the gun! Thanks!!!1!!!!
Friendo, you are in luck.
https://mega.nz/file/4DBzjYhI#5u8LKBEG-ADxk_mpXVWucUC0lqLV1ps-JSYaoQITmJI
that link contains the gun ending of Sanatorium... as well as the rest of the maps.