Is the BZ round in your initial photograph the same one as in the last picture you posted? The knurled cannelure is not visible in the second picture.
Also, I noticed that the links in the first picture are not Browning links, which made me wonder if theye were different rounds.
Regards
TonyE


Thanks for the pictures. I have a copy of that Kynoch drawing myself.
Those links are the Mark I whilst the first ones are Mark II. I did not realise that when I asked the question.
I would describe those rounds as scarce rather than rare. There used to be quite a few around but these days it would be quite hard to find one. How many do you have?
regards
TonyE