There were four different styles of NID Field Grade Guns. As originally introduced in 1926 they looked like this --



A year or two in they added the stars to the Field Grade receivers --



For 1935, they dropped the cocking indicators, went to border engraving on the receiver and went to a fuller stock with the nicest amount of checkering to grace a Field Grade gun --



After WW-II they dropped the border engraving on the receivers and reverted to the earlier style (cheaper) checkering --