The FG42 can be obtained from the Mystery Box or off the wall. It possesses a high rate of fire, high recoil, high power, and variable accuracy. It can be helpful to get rid of large groups of zombies because of its high penetration and damage, but the rate of fire and magazine size can make it more and more dangerous to use in the later rounds. It should not be used past round 16 if un-Pack-a-Punched, as it will run out of ammo in mid-round and will become useless.
The Pack-a-Punched FG42 becomes the "420 Impeller," gaining more ammo, larger magazine size, more power, and a slightly faster rate of fire. Like the un-Pack-a-Punched version, the 420 Impeller should not be used carelessly, as it will run out of ammo quickly. It is best to go for headshots and to fire in short bursts to conserve ammo and to be more accurate.