Just finished re-reading this thread and the notion that caseless ammo is a dead end made me laugh. There's a company in Austria called Voere that produced a hunting rifle using a caseless round. They started manufacture in 1991 and it was still selling well enough in Europe as of 2007.
Then there's the US Joint Services Small Arms Program project called LSAT (Lightweight Small Arms Technologies) that was investigating among other things, tech that makes ammo lower in weight. As far as they're concerned, the caseless ammo of the G11 is a proven technology and it formed one of the options they were pursuing in an effort to make both weapon and ammunition lighter overall. They were using a licensed 5.56mm variant of the ammo tech used for the G11.
https://ndiastorage.blob.core.usgovc...tl/Spiegel.pdf
https://en.wikipedia.org/wiki/Lightw...s_Technologies
https://en.wikipedia.org/wiki/LSAT_caseless_ammunition
https://www.textronsystems.com/what-...r-systems/LSAT