16 Bore with Brenneke slug

I thought this looked like a nice / interesting cartridge so wanted to share the images. It is a 16 Bore loaded with a Brenneke style slug. It has a knurled ring, painted white, crimped into the card tube to securely seat the slug in place.
image image image image

Right and left from the “Rostfrei” you see some dots.
I have heard that these dots are a code that tells us the year of manufacturing, depending the position of the missing dot.

Perhaps @polman can tell us more.

Very interesting Dutch, thank you. I was wondering about the age of the cartridge, just knew it must be post 1928 (thought maybe mid 1930s?), so would be very useful to identify this code to see how wrong I am! Pete.

Here are the codes mentioned by Dutch.

Regards René

So according to this list your case is from 1967. Regards René

Edited for changing year.
Don’t look t lists after two beers😩

Thanks very much René. I was only around 30 years out then! A timely reminder why I shouldn’t meddle in shotgun cartridges… Pete.