Increasingly the taking of pictures is forbidden in the museum. I can see some logic in this, as with large crowds the taking of pictures would interfere with the progress of visitors. On the other hand, it is possible in most museums in the West, and gives no problems there.
The government site expresses it so much better: "Please, do not take photo inside the exhibition halls in which contains/displays objects for avoid interrupting other visitors' tour and avoid harm objects with flashlight"
Whatever, these pictures are of an age when it was not forbidden yet.
The collection is nice, but if you are a weapons buff you should visit the Military Museum elsewhere.
In 2016 the collection was housed in the second courtyard.