Revolver locale

[pjac1]

Somehow I missed the revolver! In the coastal ruins section I need the revolver and sight to shoot all the bullseyes. I have the laser sight, but not the revolver. Please help me in locating. How far do i need to go back and get it?
Thanks for any help.

[tlr online]

Level 23 City If The Dead is the first documented location of a revolver, but there are others hidden throughout the levels. You are also able to use the crossbow here if you do not have the revolver.
* Users: Please use this thread to post further locations of the revolver, thanks.