Also - keep in mind that the 'roll' is imparted by the pivot, by Acc #4 'dragging' the left arm so as you uncock 'down', your pivot 'throws out' and rolls. If you do some start down waggles in which you exaggerate the uncock 'down', and hold your pivot until #2 is basically fully released, you'll see how the body (#4) 'drags' and brings everything 'around'.

This is a very useful way to feel the 'swinging gate' of the horizontal hinge action (using the pivot to feel the 'horizontal' nature of the 'around' motion - a lot like throwing a frisbee).