Hi Cornelis,
First of all, two of your images have sort of killed at a blow a collector's hope of mine cherished for 30 years.
The short three stage copper alloy ('brass') arquebus barrel dated 1516 was sold Sotheby's, 23rd May 1978, lot 212, and I had been hoping it would turn up in another sale since I started collecting shortly after that auction. Now, sadly enough, I have to accept that it is in that French museum.
It was cast in Nuremberg and the arms are those of the von Schlaberndorf family of Brandenburg, Prussia, which produced an archbishop named Georg, who was Bailiff of the Johanniter Order in the early 16th century.
The length is 80.65 cm, the caliber ca. 12 mm. The pan cover is missing.
I enclose four images.
The first organ gun the images of which I enclose once more below employs older European arquebus barrels of ca. 1540, the second is made of Indian matchlock barrels.
I mistrust the wooden parts of the two early barrels; the one of the handcannon is obviously a modern reconstruction.
Thank you so much again for posting!
Best,
Michael