Dating an old Petromax

HI Folks, long time I don't partecipate to this forum, hope you are all good!

I'm restoring an old Petromax that I purchaser recently and I need your help to confirm my assumptions for its age and model (the lavbel il missing).

I join some pictures of the lamp and the elements that for me indicate that it should be an 838/300 built around 1939 and 1941, possibly on April 1940 if I interpretate well the inscription in the bottom.

What do you think?

Thanks!

Carlo

Thanks!

Now it works back, it's always an emotion to see a >80 years old lantern coming back to life