Looking for information caseless "Troika"

Updating the new ammunition.org website I have found a “small” problem with this caliber. This is a 5.56x 21 US Caseless Troika. In “theory” it is a caliber made in the USA. But I don’t find any information about it, neither in Woodin’s book (volume III). I know there are two models: B1 and B2. Can someone please provide information about this caliber?..and What is the difference between the two models? I attached photo taken from ECDV

No one can give me information??

JJAM, when I google “5.56x 21 US Caseless Troika”, in images I get nothing. Without the Troika, I see a bunch of caseless, including one of Jim M’s that looks like the one in your other post.

THANKS !! Dan for your answer. The name “Troika” is not mine. That “denominatión” I have seen in various lists and collections. But I don’t know anything. It may be a clue to find information about some of the caseless cartridges shown … I think it will be a very long afternoon looking for information (je, heh).

JJAM,
for what its worth. I have two of these rounds in my collection and they are labeled “Troika”. Not my description, that is how they were labeled when I got them.
Zac

Thanks Zac.