How does a pump action marshmallow gun work?

How does the gun pump action work, not the one made out of pvc pipe that you blow into, but the ones where you can put in 20 mini marshamllows, or the ones that shoot 3 or 4 regular marshmallows.

Fizzxwizz7 years ago
Many of the pump action guns create pressure when you pump it backwards and the size of the marshmallows creates a seal and by the time it is pumped back fully the pressure shoots the marshmallow out.