What do you consider proper pickup placement? Closer to the bridge? At an angle?
First and foremost to make sure that the B string is well within the magnetic field - I once scooted a bridge 1/16" over and it made all the difference in the world.
Also, I find a good bridge pickup is essential for maximum low-B effectiveness. It just doesn't growl & project as well with only the neck pickup IME. (Can't speak to exact positioning. I don't care for it right up against the saddles, though - I like it at least an inch or two out to catch a bit more string wiggle.)