Now, the one at the top of this page (from the other now merged thread) is very North German-Dutch looking. I suspect that the barrel is tapered and flared, just not very much (nothing was really straight at the time!). It does look pretty straight in this picture though! I'd have said that it was more like 1710 or so. How long is this barrel?
They did a lot of big, heavy barreled target rifles (15-20 lbs.), with long, heavy, straight-ish barrels, with hooks or flanges or some other apparatus for hooking the muzzle end of the gun against a bench. They also often have a pull out shoulder rest in the buttplate! :grin: