Welcome here Echo!
Talking about Russian ones (other countries excluded):
The first two likely were the initial production. Since the weapon is the M1939 the date of production should go along with the first guns.
The AP was produced till the caliber got cancelled (in the 1970’s maybe).
The UOR-167N is a post war design and replaced the UOR-167. As far as I can say by some specimen the change might have been around 1950-1952.
The caliber was made at least till 1973 since this is the latest Russian head stamp I have seen.[/quote]
Thanks EOD. I appreciate the help. I’m a wargame designer and am looking for production dates doe all sorts of ammunition. A friend over @ TankNet recommended I ask here for this data. I truly am grateful for the data.
Have just this evening found another Russian round that went with the M1939 Weapon System.
The UBR-167P. This is an HVAP round. Would you happen to know it’s production date?