From the horse's mouth (e.g. Graham Greener):
"Over the years barrels have been made from various steels and Damascus iron & steel mixtures. ZSR is a specification for the steel used in the manufacture of the barrels of a gun but I do not know the exact constituents. We have used many different types of steel ZSR and ZS2 frequently feature in our records and are probably similar to the EN19 and EN32 we use today. I am sorry I cannot provide more details."
Well this pretty much rules out a vendor name and leaves a custom spec'ed steel.
The gun is "as new" and I am not saying this lightly.
I'll post additional pictures later as I am leaving for a hunt in a few minutes.
Have a great Sunday!
WC-
