A BOAVSM is a bullet the wielder cannot distinguish from a SilverBullet, because it never failed to kill any lycanthrope encountered. The wielder will leave the actual metallurgical determination up to others.
A BOAVSM is a process that solves problems very well. It is almost a SilverBullet. In the real world, of course, there is NoSilverBullet, but we can come close by finding good, solid practices that consistently solve significant problems.