Fixed that, thanks for catching it.
Uh you mean SG (Bearing Version 2) with Fortress Base? We recently settled that fortress base can only use one set of metal balls, and fortress' bases apalling shape makes it a pretty bad idea for SG BV 2 (though it's one of the better ways to use fortress base). As for your actual question, they *can* shift around in battle and move out of the holes and ruin your balance but it's not overly likely, and they won't fly out.
Uh you mean SG (Bearing Version 2) with Fortress Base? We recently settled that fortress base can only use one set of metal balls, and fortress' bases apalling shape makes it a pretty bad idea for SG BV 2 (though it's one of the better ways to use fortress base). As for your actual question, they *can* shift around in battle and move out of the holes and ruin your balance but it's not overly likely, and they won't fly out.