Yea gunz is the only oen I can think of. Why do people like dual revolvers so much..? Seriously in real life people have 2-3 guns on them but they use both at the same time, shooting two guns at once severely kills your accuracy, both your arms are being given shock, steadying is impossible lol.

CoD2 a FPS (not free) has a revolver pistol for the brits but it's nothing great...