Well, what I wanted to do was access the Z position of gameObject's LineRenderer so I could adjust the finishing length via Playmaker. I couldn't work out how to achieve this so I had to go for plan 'B'.
In plan 'B' I had a LineRenderer componant with a Z position fixed at 500 so at run time it drew a line from 0 to 500 starting from the gun turrett. Then I had to set it up so that when a raycast hits an object, the first LineRenderer is deactivated and a DRAWLINE action fired with the END position set to the raycast's hitPoint.
It works fine but it wound have been easier and cleaner to have access to the first LineRenderer's Position Elements so I could just plug-in the dynamic Z variable to the Linerenderer's vector3 Z position, and not have to activate/deactive the LineRenderer and create a DRAWLINE action.
Hope I explained that right.
Anyway, it works the way I have it setup and it's still a simple 2 state FSM - albeit with 4 actions per state.