For a support or sharpshooter role you obviously want something with some range and accuracy. Depending on your price point you might wish to consider a TM m14, a really wonderful gun for range and accuracy and good for a skirmish as well. I also find my CA M15A4 good for both roles because when you get it upgraded a little and get the hop dialed in the range is pretty good.
I would also suggest the KA FN FAL but it might be a little too big for you.
You can't go wrong with a good quality AK or M16/M4, because when they are upgraded and dialed in they can be good for the dual role.
Think carefully about the "sharpshooter/support rule" as many people do not enjoy it as much as expect. Besides you young folks are supposed to run around so us old guys can hang back.
On the AVing issue I will be in London all day Sunday doing the WWII and then the Western game, so feel free to come out and track me down.
When the elephants fight, it is bad for the grass. When the elephants make love, it is also bad for the grass.