Hi 'Nando,
Thanks a whole lot for promoting my threads, my friend!
Here is the original, actually existing late 14th century example which your fine reconstruction work illustrated at the end of your latest post is obviously based on. The hook is a modernization of ca. 1430, the earliest date when hooks on guns turned up first as I stated on several earlier occasions. The hole drilled thru the stock was most probably for pivoting on some additional mount.
It is preserved in the Firearms Museum of Suhl, Thuringia, and measures about 65 cm overall. It was a find from the attic of a nearby Schloss!!!
Best,
Michael