Rod,
I think your special railway is a bit later than the Hampden Ball watches.
While quite a few companies had high quality, high jeweled movements... The 17 jewel adjusted movement was still the railroad standard in 1898. (Iirc)
Hamilton 936 & 976 Ball watches.. 17 jewels. (The 976 may even be 16 I'm not very read up on Hamilton). These would have been around in 1898.
As much as we romanticize the railroad watch, it was a tool.
15-jewel Railway grade movements, signed Ball’s Standard Adjusted. When they had a 23 jewel models like this one
They didn't have a 23 jewel 18s movement then. With open faced: Ball used Hampden grades 59 & 60 (15 jewel) for high and superior grade. These are mid to late 1880s.
After that used the grade 68 which was a 17 jewel movement around 1890.
The special railway was a 17 jewel untill at least 1896. So the short answer is they didn't have movements like yours to offer while using the 15 jewel. Even at that, it's been written that Mr. Ball disliked excessive jeweling.
I'm enjoying this thread, thank you. You've made me go back over the Hampden Ball watches and it was interesting to compare dates with your watch and other special railways.
Here is one add from this forum I can actually link, dated 1896. 17 jewel special railway.