12.7 soviet colour codes?

[nathanieljr]

Hi all,
Saw these up for sale, and was confused by the 3rd colour band from the tip. black and red is the API loading, but I cant find any reference to the third colour.
Any ideas?

 

[Nabob]

This is a czechoslovak cartridge 12,7 Nh 50 or 12,7 NhSv same as PZ or PZSv but with inert compound instead the incendiary mixture.
Bob

 

[nathanieljr]

brilliant, thank you.