A good observation Michael
Would this barrel been fastened by iron bands? I can not find the loops onder the barrel you otherwise would see, but the pictures are not that revealing either
I found this at Bonhams, they say it is around 1500 but there is no real hook, more a rectangular "hook". So earlier? (bonhams 30nov 2011)
http://www.bonhams.com/auctions/19002/lot/244/