Rigging the front brake

Is there room for the bb to get jammed in between the side of the plunger and the housing? I don't think wear on the adjustment screw has ever been the issue - I've seen an entire line of new KTMs on the dealer floor with the adjuster screwed in all the way and still too much play. Be careful with that bb fix, if I remember right the end of the plunger is rounded, I'd be more concerned you could end up getting it jammed in there. One other thought, does your front brake "pump up" during a ride, or when left overnight with a tie wrap holding the lever in? If so, you could be trying to make up (in adjustment) for a sloppy bore and/or worn m/c seal kit, which could lead to a lockup once the brake fluid get's warm and the seals expand a bit.
Someone had posted some data about a year ago on the Holeshot board about the distance the internals had to retract so your caliper will release, don't remember exactly what, but I do remember an experiment gone wrong of mine 20 years ago where I had "overfilled" the m/c resevoir on a street bike with twin disks by topping it off completely with pads off, pistons slightly engaged, then putting the pads back on. Finally I had brakes right out at the start of the lever pull instead of in by the bars. Rode about 10 miles, gave 'em a big grab, and down I went, brakes completly frozen. Real problem with the brakes, as I learned later, was that it was a dual disk setup with a master cylinder for a single disk (custom setup from the previous owner). The m/c simply didn't push enough fluid to engage until the lever was halfway to the bar.
Let us know how it goes today.

Best thing is to adjust the red knob to a few turns from fully in, then remove the red knob at the end, adjust it in a few turns with pliers, then refit the red knob, this will give you a few extra turns of adjustment.