Hello Raimey,
I am not familiar with Cordy - barrelmaker?
on the JBL I had the same train of thought - L for Liege or an initial? - don't know.
there is a list of Belgian makers marks/names on damascus-barrels.com -
JBL is in that list, but it says: unknown
- so much for that
- my luck to have a barrel with the one mark which seems to be unknown...

regards
Gunter
NRA Life 1974