[PvK]

Without knowing how the weapon is set up, it's hard to say, but from a Newtonian perspective, sure you have have a "jerk" from something that doesn't release anything. Try putting an energetic cat or dog (or yourself) in a box. An animate object in a box can shift its weight around in the box and make it hard to hold the box still. If it tries to run or jump inside the box, the box will jerk one way and then (when it stops/lands/hits the wall) the other direction. Net force may total zero, but it will move around. A clever animate object can even roll and jerk and get itself to move around using friction, rotation, and/or gravity, without leaving the box.

PvK