Dan, I think the flushness of the inlays is right for some gun styles and periods, but not for others. I believe it certainly is the accepted 'norm' for contemporary work. This is what we have been accustomed to assume is correct, as contemporary builders. Many things we assume are 'right' are often repetitions of other contemporary work. There is nothing wrong with that, it's how style of work and design evolves within this longrifle culture. It's how the guns evolved and developed back in the day. Working for a master, you pick up his style. Looking at other men's work, you absorb details you wish to incorporate.
That said, to truly understand what building was back in the day, the smith of today MUST study original work whenever possible. One of the beauties of the web is that we get to view photos of original work and get to discuss it on line. Not as good as holding the gun in your hands, nor having an original for a bench copy, but it's a far cry from what was available to us out in the boonies in the 1970's.
This appears to be not inlet fully flush, from birth. This looks almost like applied decoration, rather than inlaid.
Note the profuse nailing of the inlay material. Probably needed to make the brass lay down. Got a high spot? put in another nail. You do not see this kind of treatment today. There is a certain casual approach taken by Kuntz to get the effect he wanted without resorting to a thick inlay that must be painstakingly formed and fitted to the wood.
Also note the nails going thru the middle of the inlay and the screw on the forward extension of the guard,. The ramrod hole must be to one side of the fasteners, or the rod ain't coming out of the hole!
A view of the finial. Looks raised off the wood. I think much of the raised effect is due to the inlay lifting and then dirt and oils getting underneath the finial.
A closer look. The eagle appears very nearly flush. I imagine that originally the parts were not inletted any deeper than this, slightly proud of the surface. Note the area inside the eagle's bill is brass that has been cut down and blackened, rather than cutting the contour out and inletting. Kuntz certainly made an effort to simplify the inletting.
Photos by TC, and used with permission from The Metropolitan Museum for educational purposes. Not to be published or printed without permission from the Met.