I have a couple of unmarked early Colt .45 cartridge cases that were turned up out west, and I’ve tried to discover their manufacturers. They are very similar in appearance, having flat heads and Boxer primers, but one has a small primer and other the large Boxer. Careful examination has not clearly indicated to me that either is of folded head design or “balloon head” solid head type; both weigh about 80 gr.
In examining available source material it seems UMC never made a Colt .45 with the small Boxer primer. They began manufacture of this caliber with the Orcutt primer, and switched to the large (.210) Boxer no later than 1880. WRA did make this caliber with the small Boxer at least periodically. Their earliest production of this caliber (I’m assuming 1874) would have predated the .210 Boxer primer I think, which was introduced by Winchester with the .45-60 and .45-75 rounds used in the 1876 Winchester rifle. I also have a Colt .45 Case with the W.R.A. Co. headstamp which is fitted with the small primer; this latter round dates from some time in the mid 1880s or later.
Most headstamped WRA made rounds in this caliber do have the large primer. So I’m inclined to tentatively assign manufacture of the small primer case to WRA and the large primer specimen to UMC. Any thoughtful comments will be carefully considered. Jack