Mine isn't set up as a BOB because it was designed for the MPX and mags only. I see a BOB as something with backup meds, some food, first aid, my G17, Sub2000, (4) 17rd mags and (5) 33rd mags with +P 125 Gold dots.
Anyway, I wanted a mostly nondescript backpack to keep my SBR close. The layout had to prove the rifle was not loaded in the case because WI rifle transport laws suck and although it was a pistol at birth I didn't feel comfortable with trying to explain that to a cop on the side of the road. Besides, why would I pistol that, if I am resorting to just a pistol i'll take my above mentioned 17 with a fun stick and probably shoot better then holding the MPX because the VFG would need to removed (as a pistol).
The other thing I felt was important is retention, I didn't want my MPX to flop around. I want to open the cover and it be in the exact same spot every time.
I bought the foam on Amazon for a few $$ and after sizing it I sprayed it with plastidip to help prevent wear.