The butt-extension on this pistol, which has every appearance of being part of its original design, is apparently unrecorded elsewhere.
Integral ball pommels are mainly found on wheel-lock pistols of the third quarter of the 16th Century - for instance several in the Muse d'art et l'histoire, Geneva (e.g. nos. 56-59, described and illustrated in Jos-A. Godoy, Armes Feu XVe-XVIIe Sicle, Geneva, 1993).
However, assuming the coat-of-arms to be correctly engraved, and original to the pommel, the pistol must date from between 1608 and 1612, which is close to the date of a wheel-lock rifle in the Victoria and Albert Museum (no. 2240-1855), that is dated 1605, and has a lock of similar form.