During the light side missions, you may encounter a team of 5 B2's and 1 B1. (for example, Light Side 5-H) If you attack the B1, every single B2 will display "relentless barrage" but only a few will gain the turn meter. Also, on a lesser note, attacking a B2 will not trigger the "relentless barrage" of a separate B2. (this is probably intentional, but I thought id bring it up). If you want to test it, play Light Side 5-H and attack the B1 battle droid first.