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In one of the images there appears to be a marking on the barrel.
Or is this just a smudge/dirt?
There is certainly a good possibility that however it was marked/sold it may have been produced by Fratelli Brivo.
The torpedo shaped track nuts are certainly distinctive. Cannot recall seeing them afore. If you envision searching, keep them in mind - perhaps the best clue.
Another member who may be able to shed illumination is @
amirinisrael ...
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