This video, probably filmed by a police officer, shows police officers in Rio clearing a favela (slum). There are many shots of a officer using a Madsen machine gun.

At 20 lbs (unloaded, I think) it is heavy gun for a magazine fed weapon. On the other hand the weight helps counter the recoil and, lets face it, it looks really badass!

On a related note, I highly recommend the movie Cidade de Deus (City of God) (2002). It is about the life of two boys who grow up in a favela. The DVD also features a documentary about the police who, in theory, police the favelas.

[ Many thanks to Tarkan for posting the link. ]