Join Date: Sep 2008
Location: Bavaria, Germany - the center of 15th and 16th century gunmaking
High-Gothic hand cannon, ca. 1380
Your barrel is definitely datable to ca. 1380-1400 and may well be of Portuguese origin. The stock and bands are modern reconstructions but convey a good impression of what the piece might have looked like more than 600 years ago.
Several barrels of similiar shape and dimensions were dug out from the battleground of Aljubarrota; the battle took place in 1385.
The attached image is from Prestige de l'armurerie potugaise. La part de Liege. Musee d'Arms de Liege, exposition catalog 1991, p.42.
Unfortunately, this photo shows two originally separate small barrels, one round and made from wound band iron (the older) and the other (the later one) octagonal, obviously foolishly hammered into each other for some reason at some later time. So just concentrate on the left barrel, the round one, and you will see the close relationship to your piece.
I also enclose two images of a very similar barrel from Aljubarrota in my collection; it is of almost identical statistics as yours. It is made of wound band iron and fire-welded, just as those found in Aljubarrota, and may be as early as ca. 1360. There is a maker's mark, an arrow head, deeply struck in front of the touch hole which indicates that this workshop was traditionally associated with manufacturing heads for crossbow bolts and arrows. The catalog text given below also mentions a mark in front of the touch hole.
If you are a bit into earliest firearms you might like to view my other postings.
Have fun with your piece.