I think it's more likely that a BB would push through the rubber trim that seals the goggles to your face than through the gap created when they are open as I've just just tried pushing a BB through and it just got stuck about 1/3 of the way through.
Thing is if a BB pushed through the seal, unless you have the V12s so loose they are dangerous anyway I would be confident it would completely drop the velocity of the BB as it gets inside, whereas I'm sure I am not the only one that has got a welt from a Ricochet at close to medium range
The main weak point I've noticed is there is a small gap where the bridge of my nose is, but it is about half the width of a BB and I guess would depend on the shape of your head/nose. I toyed with the idea of putting a couple of thin strips of padding along that area but I think it will make them more prone to fogging.
I had some Heroshark eyepro that was roughly the size of ski googles and they had slits on either side of your eye that a BB would fit through, albeit snugly. Again I toyed with plugging the holes but never bothered as they were my backups, till I lost them/someone stole them.
