Hi Mark:
Both the hole for the lanyard loop and matted sight channel were deleted around serial number 800,000 as production expedients. Prioer to that they had appeared on all models and variations. The high gloss blue finish was dropped around 10,000 numbers earlier. The slides were electro-penciled with the last 3 digits of the serial number on the cross bar as shown in your photo -- this was done until the end of the war, I believe.
Hope this helps,
JB
Both the hole for the lanyard loop and matted sight channel were deleted around serial number 800,000 as production expedients. Prioer to that they had appeared on all models and variations. The high gloss blue finish was dropped around 10,000 numbers earlier. The slides were electro-penciled with the last 3 digits of the serial number on the cross bar as shown in your photo -- this was done until the end of the war, I believe.
Hope this helps,
JB