Tallahassee found a Heckler & Koch MP7A1 in the back of a Hummer he discovered shortly after losing his Cadillac Escalade.
The MP7A1 is a Submachine Gun designed, developed, and manufactured by Heckler & Koch as a personal defense weapon. The weapon fires a HK4.6x30mm round which was exclusive to the MP7 when it was first introduced. It is also a select fire weapon which means it can be Semi-Auto, 3 Round Burst and Full-Auto fire. It is compact and light, as well as very accurate.
Tallahassee in the film Zombieland used the Heckler & Koch MP7A1 to kill off much of the zombie horde in Pacific Playland. He also fired off a few rounds into the air when he and Columbus first discovered the yellow Hummer with a large duffle bag of weapons.