Thsnk you so much for the link and for being so thoughtful, Jasper
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As a matter of fact i know Rainer Daehnhardt, with whom i have a fair relation. A lot of knowledge that i transmit here in the forum comes from his books and 'lectures' i receive when i periodicaly visit his shop in Cascais ... as also (a couple times) in his house, where he has an imense (i mean imense) collection.
I am also aware of the article you linked and i also met its author Antonio Cejunior when he came (from Macau) to Portugal to visit his family.
I visited the cannon site you suggested and i saw the cannon you refer; not so 'lantaka style' as the one posted here, i would say ... don't you agree?
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Not pointing at any source in particular, i don't feel safe with determined attributions like antiquity and provenance, specialy when it comes to 'Portuguese' or 'Spanish' cannons conotations ... discoveries period and all that. Indeed cannon foundries were settled in Macau (the famous Bocarro family) but i don't know if the typology produced there is connected with lantakas ... or even 16th century breech loading berços.
Dank u once again