According to my copy of "Weapon Tests and Evaluations" by Kokalis, he had a .44 Mag Redhawk rebarreled and suppressed to shoot .30 caliber bullet loaded in a necked down .44 Mag case. No word on Russian cartridge, though. The book was published in 2001, so it may have come later.
Upon closer reading of the article:
- It was originally published in Sep. 1992 issue of SoF
- There were two pistols made, one a Ruger GP-100 (no caliber indicated), the other Super Redhawk .44 Mag.
- The suppressed GP-100 fired a 5.56 bullet, the Redhawk .30 caliber. Both bullets are solid turned brass.
- They were not necked down, but rather bullets are "encased in an aluminum piston with a black-plastic front face seal" This may be the "telescoping round" you were referring to.
However, no Russian anything was mentioned.