A hand cannon ... or not ?

[fernando]

This piece was already posted in the Ethnographic Forum.
Several opinnions were given, as to this would be a signal cannon, a hand cannon, or nothing of the kind.
We have settled in the hand cannon version, but not without prevailing doubts.
16th century was the age proposed by the seller, a non specialized guy, trading in a flea market. He also said it is Portuguese ... at least he acquired it in Portugal.
I would like to take the oportunity of having in this Forum persons who are within or close to this area, to request some further coments on this specimen, as well as its hand cannon plausibility.
The exterior diameter is 7 cms., the length 18 cms. The bore is about 4cms. at the muzzle and about 3,3 cms. at the bottom. It weighs 3,4 kgs.
The tube interior is sleeved.
At the stage that i was (nearly) sure this is indeed a hand cannon, i had a stock (pole, haft ?) made, to pretend how the thing would be "on the field".
Thanks in advance.
Fernando