I've been doing the same thing.
What is interesting is the yellow 37 you see on there appears red in normal light but comes up yellow under a camera flash. Have you ever seen that? The Yellow (red) was there when I got it from factory storage. The red-red was what I added so the markings stand out.
Red dye number 2?
It’s likely the angle.
Some dyes use different minerals and metals to get the colors you see. Red mineral or metallic dyes often use gold, which, under the right light conditions, could appear yellow. Likewise, green dyes often use copper. If I recall correctly, cobalt used in blue dyes can appear silver or even black, but I would avoid blues just because it would clash with a blued receiver.
What fiber/nylon stocks do you use on your Mosins? I’ve always been a wood guy myself, but I want to convert a carbine to a fiber stock.