They look like Charles R. (Bob) Olsen’s “Invicta” cartridges. He saw it as the basis for achieving higher velocities in a revolver without the need to use a heavily bottlenecked cartridge case with its setback problems. The trick was that the barrel was only bored large enough for the projectile. The larger sabot/sleeve stopped against the rear of the barrel, sealing the gap between the cylinder and the barrel, adding to the possible velocity achievable.
The models he showed to the shooting press back in the early/mid-80s were built on Dan Wesson revolvers. I suspect that no one wanted to market it due to the possibility that some idiot would slip a standard cartridge into the cylinder and try to shoot it out of the smaller diameter bore.
Olsen’s US Patents can be seen online:
KAC’s Reed Knight and John Anderson later appropriated the Invicta concept to develop a pair of suppressed revolvers. The sabot/sleeves solved the common problem with previous attempts to suppress a revolver: the escape of gas through the cylinder gap.