Fucking nearly was done installing a mortise door lock, when I discovered it's the wrong hand lock FML. I thought I was being clever a while ago and bought the opposite hand lock, because I wanted it upside down, not realizing the fucking lock handle goes on the inside of the house and the square pin DOES NOT HAVE A SQUARE HOLE ON THE OTHER SIDE. I SWEAR IT'S A FUCKING SCAM. Had to disassemble the lock and flip the fucking latch. What a greasy ass mess. So much time chiseling and fucking with the lock. FUCK.