If you munch food, you eat it by chewing it slowly, thoroughly, and rather noisily. Luke munched the chicken sandwiches Across the table, his son Benjie munched appreciatively Sheep were munching their way through a yellow carpet of leaves. to eat something noisily munch on/at (Probably from the sound of food being crushed)
This sound is reserved exclusively for the shotgun most notably used when firing several single shots in rapid succession at a close enemy The shotgun may be referred to as the Munch-gun