[sdmark777]

Doubs, I don't understand what you are saying about the safety marking changing from bare metal marking to gesichert? The checkered safety may have changed to the new grooved style, but the gesichert marking came way later, like after the 1906 model. Or did I misunderstand?

For example:
1)1900 AE with 5 digit serial # and late safety
2)1906 AE 9mm