I will never know.......................
I have a nice (about 90%) shooter grade, 4", recessed but not pinned; 27-2 dating to about 1980
My 1939 6 1/2 inch RM appears to be unfired since leave the factory...... and I will keep it that way!!!!!!!
So if I could have only one....... the 27-2 is much more useful!!!!