The lead is carrying a Dragunov Sniper rifle, No 2 has an AK variant and the guy in the rear is carrying an PKM, a sort of Soviet GPMG. As to nationality, I have no idea except to say Eastern European.
SS is right, thats an NSPU night vision sight on the AK. Also, that AK appears to be a wood-stock model with (elastic bands on it) as opposed to a folding stock model that you would expect to see in their SF-type outfit.
Or they could be very convincing/sad re-enactors from Surrey.
Airsofters don't go out in the rain. I painted a load of brick 'houses' that a bloke who owns a paintballing/airsofting place had built for them to run in and out of a while ago. Apparently they don't like getting their stuff more than slightly dirty whereas paintballers get extra muddy since the coveralls aren't theirs.