Gun or Paintball Marker?

At first glance, would you think this to be a paintball marker or a gun?

Paintball Marker Gun Other

Despite the constant air CO2 tank, paintball buttstock, paintball markerish grip, and Tiberius style body, this is actually a real firearm. A recent post on the Firearm Blog reveals that this is a gas powered submachine gun that fires .177 or .22 metal BBs.