They are a random spawn. You just need to be able to get to the magnys lighthouse area.
You have to kill mr bubbles without hurting lil sis (not sure of it requires not hurting her or simply not killing her)
After bubbles is dead she will give you the gun
Edit: i know they can spawn right near the lift that takes you up to the area with the lighthouse itself. I think they can also spawn on the little island where the radio station sidequest is done --- Crazy? Crazy with low prices on Wind Brahmin. You buy one!!
they usually spawn for me at the top of the hill once you cross the train tracks after you fight the stalkers.. and ive seen them waiting in the area where you fight the wave, never saw them during the wave. --- KaBoom1322 Posted 2/26/2013 12:56:24 PM My BAR is only 20k :( ..
As soon as you drop down from the railroad tracks to the level where the elevator is. They will spawn at the building that has the big opening in front of the elevator. If they do not come out as soon as you drop down. Save and quit and go again. It took me 1 out of 3 try's to get them to spawn. Lil sis can't take any damage. You can go on you-tube look up Yoteslaya video on how to get it. --- I payed for this game, so I play this game the way I want.