If the the trigger is slightly wider with a case colored face like the above posted pic its a later one that has been swapped,
If the trigger is thin standard width and shiney or blue it has been smoothed.

Except for snubs that barrel end ejector rod "LERK" knob style was used pre war , WWII and early post war.


If you look at the evolution most changes simplified production, The LERK required a matching notch cut in the barrel as well as attaching the separate barrel end to the rod where the modern style rod is one 1 piece.