Did I break this Luger? Bolt stuck open

[Vlim]

Sounds like the magazine is the problem. The button should be tight and straight against the body. If there is too much space between the button and the mag body, it can get stuck somewhere.

A good trick is to try it with the grips (or at least the righ hand grip) removed. Visibility and tinkering space will improve drastically.

the hilariously-translated Parabellum manual

Which one was that?