Spoiler
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
It's located in Chapter 4, by the Hans bar in an alleyway

You need to jump/run to the right wall, then jump/run to the left wall, then jump up to the platform to the right.

Thanks. And by all means do post more spoilers, I need every one I can get.

nah... thats the hardest weapon to get in the game...... the others are to be purchased/traded or picked up...