The proof mark table can be located at Sociedad Largo website 9mmLargo.com
at the bottom of the main page. I don't have my reference material with me, but by the serial number I would guess around 1943.
Thanks, I found it about a hour after I posted here. It has a wavy line above N = 1943!
Man your GOOD!
It seems to be in the last group sent to Romaina. (BIG SMILE!) It has a few extra stamps on the slide.
Left side just above the 9 mm marking O or D inside a three sides box (bady stamped) & (badly stamped also) 3 inside the box.
Also has a marking on the right rear of the slide c 4 c running vertical with the slide surrations.
Do you know what they mean?