I've received several emails from different people telling me the "D" in RGD stands for Diakonov, but no one has provided any hard documentation to clarify this.
Folks have pointed to different web sites to support their claims:
My source for the meaning of RGD Ruchnaya Granata Degtyareva is:
Military Press of the Commissariat of Defense of the USSR, Moscow 1944
Translated to English by Maj. James F.Gebhardt, U.S. Army (Ret.) 1998
Janusz ( from Poland) has done some digging around and he finds the RGD-33 was originally developed by Diakonov, and later upgraded by Diegtariev (Degtyarev). The Russian Manual apparently gives credit to the last designer involved in the project.
So who's efforts are more significant to the final grenade design? It would be very interesting to have a copy of some vintage document showing the model 1933 as designed by Diakonov, to compare to its final form by Degtyarev.
This is similar to the history of the development of the British Mills Bomb. One could argue that it should be called a "Roland" Bomb, as Roland was the developer of the basic concept, where Mills took the idea and modified it.
I wonder if Roland, if he were in the British Army instead of being a Belgian officer, would have had the grenade named after him instead of Mills? After all he did have the first patent on the design.