Jim,
I had some RBs, but you are obviously more of an expert than I.
A large number (60-80 thopusand) of the Egyptian rifles ordered for the Egyptian government were never paid for, and not delivered. Egypt was under the rule of Turkey at the time and cash was most likely the problem. Most of the guns were never delivered to Egypt. Remington took them and sold them to the Spanish government to fill an order for about 150,000 rifles. These were early models of the RB, possible prior to 1879. thouosands of these were sold in the US in the 1950-60s. My only suggestion was that the you may have a hybrid. It would take a professional examination to tell.
How do you know it is an 1879?
Regarding Patent numbers: the patent marking dates are never the dates of manufacture. The rifle is always manufactured AFTER those dates. Many manufactures places the patent date on newly manufactured rifles as long as 25 years after the date. So the patent date marked is a limit on how early it was manufactured. What are the dates on yours? Patent numbers or dates (depending on the year) were required by statute if a patent owner wanted to sue and get damages. Failure to mark meant that the patent owner could not sue infringers and get money damages. But to keep people away from copying many folks marked their guns with patent dates long after the patent had expired. The patent date generally indicates that the rifle or pistol was manufactured somwhere in the period of 20 years following the patent date.
By the same token lots of countries adopted the RB in 43 Spanish. Argentina comes to mind, it adopted both the Model 1873 and the 1879 in .43 Spanish (often refered to as 11 mm).
I also know that many small African countries adopted the RB, purchasing from Spain and South American countries as these went to the Mausers.
Change of country 9ownership) often resulted in stripping prior marking from the rifle.
Just some thoughts,
BEAR