It works very simple, there is a needle that points outward of the gun. Once you pull the trigger, the needle quickly snaps down This makes the Pins snap in the opposite direction of the shearline. So now the shearling is free to move and the plug can turn.

The Manual Lock Pick Gun Set is designed for locksmiths to quickly pick pin tumbler locks. Rather than opening locks by the traditional raking techniques with standard lock picks, a snap gun uses a primary law of physics, the transfer of energy, to compromise locks.