There are three types of target transitions, all based on what your eyes can see. If you can clearly see both targets, that's Line of Sight. If you can see one clearly, but the other is just on the edge of your vision, that's Inside 45 Degrees. If you can see one and cannot see the other, it's an Outside 45 Degree Transition.

Outside 45 Degree Transitions are the most risky because not only can we not see the target, we don't know how far away or near it is. If we simply swing the rifle around, we might find that the threat is so close that we could end up fighting for the rifle.

By doing a proper transition and being conscious of the retention of the rifle, we can give ourselves the best chance to quickly engage both targets AND retain the rifle from a grab, if necessary. Check it out.