The OP's friend's great grandpa's revolver bears closer examination.
If there is a letter S or C on the butt... it might be clear across on the other side of the butt; then it is post WWII. S 943000 would be 1947-1948.
If there is no letter prefix then it is late prewar or even wartime. A 2" that old is pretty scarce.
If the serial number is stamped or written in pencil on the inside of the Magna grips, that is a big plus.
There was a letter on the other end of the butt, I think it was S but will check and confirm.
Neat guns in this thread!
Got some corrected backstory on the owner:
"He was a detective in Newport, Kentucky. He was involved in a lot of raids on illegal gambling in Campbell County, Kentucky and at one point had to testify before a Senate committee in DC led by McCarthy. My mom still has his badge and handcuffs."
Confirmed with my buddy that it's an S-prefix gun. He'll check inside the grips when he gets home from work.