I have reworked the gun and added a scope (at least that's what it is, I think) to the top.
This will be my last step for the model. I have found the open door version requires some additional geometry inside, so I will leave that for the interior upgrade. I'll wrap it up and make the instructions ready for a release before christmas.
For the interior (texturing and geometry) I just don't have the time now to complete it in time (and in the quality I want), so that will be an upgrade next year :-)