All of this is very interesting. I made a sheath with brass tacks that had the steel wire shanks maybe 45+ years ago. I bent the protruding ends over, sort of like the tacks in the sheath shown by
@fred fellows in post #28. It worked, but felt kind of "prickly" and uncomfortable to wear, so it was kept for display only. One of the earlier posts in this thread showed brass "spots," which have two prongs, These are still solid brass (actually formed out of brass sheet, but all brass). The problem with these is the prongs are too short to go through multiple thicknesses of heavy leather. You might get them to work with 4 oz. leather doubled over, but I doubt you could go any thicker.
As noted many times, the really old brass tacks were cast of one piece, head and shank, with a square shank. These have come available a few times in recent years, but I've consistently missed the boat and failed to acquire any of the new ones. I did score a little trove of 54 antique solid brass, square-shank tacks from a vendor on Ebay last year, and have been saving them for a couple of special projects. These do come up for sale online once in a blue moon, and you should expect to pay about a dollar apiece for them, but not much less. I don't have definitive dates, but one antique dealer (I think McPheeter) mentioned the brass-head tacks with steel wire shanks first became available in the 1860's. If that is true, and I have not been able to corroborate it, I suspect there was a period of "overlap" when both types of brass tacks were available.
There was an outfit in Kentucky called Americana Unlimited back in the seventies and eighties that sold tacks with solid brass heads and steel shanks. He made it a big issue of this in his literature, as the brass-plated and so-called "gilt" tacks were being sold, also. I bought a couple hundred tacks from Track of the Wolf maybe 15 or so years ago that have brass heads, but a forum buddy who bought some from Crazy Crow recently said the ones he received were plated. I think he said he filed through the plating on one of them to check. I haven't bought any recently, so can't comment from personal experience.
If I were to make another tacked sheath, I think what I would do would be to use the two-pronged brass spots, or maybe some of my old-stock tacks from Track of the Wolf (with all brass heads) and install them in the leather after it was cut to shape but before folding it over. I would clinch the protruding ends on the back of one layer of leather, and then fold it and secure the leather pieces with fresh, top-quality contact cement. This makes a very strong and permanent bond when done correctly. This would eliminate the prickly nails on the back. Very few of the old tacked sheaths showed any stitching to augment the brass tacks, but relied only on the tacks to hold it together. Fred showed us a super nice old sheath with the nails clinched, but sometimes the tacks were simply broken off flush on the back of the sheath. This old Crow sheath (images from Live Auctioneers) was evidently made with that technique:
View attachment 218195
View attachment 218196
Best regards,
Notchy Bob