DaveM,
I would be inclined to agree with you. It looks much earlier than that, say 1690's more like. My book on Dutch guns shows several examples that have the same achitecutre and they are dated to the 1680's. I refer to the more roiunded over butt plate, squared off comb, ballistraded rod pipes, the mannerist carving at the wrist as well as the large wheellock style trigger guard. I found this just the other day and added it to my German connection photos. Its is well worth the look.
Dave B