Left: Zastava M77B1 with a 6-position AR stock and some illuminated telescopic sight (a Leupold Mk.4, maybe) on a Midwest Industries rail mount painted tan.
Top: AKS-74U with a cheekpad, Krebs Custom railed forearm and magwell flange, TangoDown VFG, and Aimpoint CompM-type reflex sight.
Bottom: Some Saiga or another (I don't know Saigas) with a Pro-Mag 20-round drum, a Viking Tactics UVG (45-degree) vertical foregrip, and Magpul XTM rail covers.
Right: FEG AMD-65 with Trijicon RX01 reflex sight on some railed gas tube, probably an UltiMAK. The RX01 has its polarizing filter installed.