7.62x54r BZT (sectioned)

Here is another of my favorite sectioned cartridges. This is a WWII vintage Soviet 7.62x54r BZT (armor piercing incendiary tracer) cartridge for the ShKAS machingun. I find it very interesting that they managed to get all that stuff into a .30 caliber projectile. The result of course is a very long projectile. The downside to the long projectile is bore friction and the Soviets added three cannelures to the projectile apparently to create a place for the displaced metal to go to when the rifling engraved the projectile. We see this again in a new generation of all-copper hunting projectiles here in the US, proving once again that what was old is new again. From what I can tell from a Russian language website, this is the later model with the three cannelures. There is an earlier version and the two loads have different designations. Can anyone identify the two types?