Good work and improving pictures.
I enjoy the work on these old soldiers also, but draw the line at rust blue- sounds just to "messy"!
Though I have done hot salt bluing and parkerizing a fair amount.
Try a neutral grey background for the pictures. Shiny surfaces are a problem, but
open shade is your friend.
The carbine in the pictures has its barrel in the white and very reflective, as was the high polish stock.
The 1914 Erfurt Artillery was re-blued and polished a bit.
These two were done inside with artificial light, would do much better in open shade.