[Ron Wood]

It could be as simple as removing the empty magazine then pulling back on the toggle a bit and let it go. The Luger has a "hold-open" device that causes the toggle to remain open after the last round is spent from the magazine, that way you know the gun is empty and immediate reload is required before the next heated social interaction. Removing the magazine allows the holdopen to drop back down once pressure from the breechblock is removed by pulling back on the toggle.