I have added a working flakvierling (from tutorial) to my map for no other purpose than a little panache. I even accept the bug about the sight picture because after all it is only a game and its about having some fun. Here it comes......
But is it possible to set some of the arc parameters as is done with an MG42? i.e. toparc, bottomarc, leftarc etc. to the flackvierling? All I want it for is to be like an anti-aircraft gun and just to make loads of noise and perhaps to whack someone in the highest points in the map.

Try it?

No effect when using the same arc settings as an MG42, so that knocks that notion on the head. Restricting arcs would be the icing on the cake as the flakvierling adds just that little extra dimension of ambience to the map.

Maybe there is someone clever enough to think up some sort of script type thingamabob to do just that.

i think you have to edit the weapon or vehicle file used for the flakvierling

If that is the case then I don't have the faintest idea where to start and even less to modify any scripts associated to any file.