Join Date: Sep 2008
Location: Bavaria, Germany - the center of 15th and 16th century gunmaking
Neither did I.
Anyway, viewed from the stylistic aspect, this seems to be one of the earliest hooks, of ca. 1430, as it is quite small in proportions.
Hooks on stocks, though, do not appear before the 1630's.
There is a small series of seven long matchlock muskets (overall length 1.72 m) known, the barrels and lock bearing Suhl marks; they were sold from the famous armory of the Counts of Giech, Sotheby's, 1974. The stocks are all branded with the alliance coat-of-arms of the Giech and Kaunitz (they married in 1633), and the hooks are fixed at a blued iron basic plate that is nail4ed to the underside of the forestock.
The finest of the seven pieces is in The Michael Trömner Collection (top atts.).
Shortly after the end of the Thirty Years War, Austria developped another long matchlock model M 1657; quite anachronistically, a small series of those musktets (overall length 1.72 m) was equipped with a hook added to the underside of the forestock by an iron cuff and four wood screws.
A specimen was sold from the Higgins Armory, Massachusetts, with Thomas Del Mar, 7 May 2014, lot 268 (next 2 images attached).
A finely preserved sample of that long gun military model, from the ordinary series without that additional hook, is in The Michael Trömner Collection (bottom atts.).