Lived here since 1989, sometimes you do see them with MP's and shotguns. Like when there was a raid on an Apartment complex near where I live - about 30 cops, heavy artillery, vests and dogs never found out what actually happened - or on patrol in the vicinity of some of the embassies (Turkey, for example).
But the worst thing about german cops is the fact that they get to carry guns, but hardly ever get to actually fire them (something about cost cutting and the cost of ammo and range time). It turns out that they average something like 1 or 2 range days a year. I shoot more than that when I'm on vacation, and I can't hit the broadside of a barn. Every once in a while you hear about an arrest involving the use of a police sidearm. Usually ends up with someone other than the criminal being shot. I.e. the guy who stabbed the egyptian woman in a courtroom in Dresden earlier this year - the cop shot her husband instead of the killer. Or the cop who discharged her gun in the middle of the very crowed Nürnberg train station at rush hour while in pursuit of a suspect (no one was hurt). Or the two cops who shot each other during a traffic stop gone bad, because they positioned themselves on either side of the car, at the front window and then opened fire on the driver.
There are more stories, but the general theme is when you hear about a cop using his gun in germany, it tends to include some mention of which person or object - other than the suspect - was wounded or damaged.