Need Help With Markings on Barrel Lug

[Gunner]

You have the advantage here since you have the barrels in hand. The second letter looks to be "L." What is the first a "J." or an "O." perhaps? How low a serial number is this gun and how is the top rib marked? Are there other stampings forward on the barrel? Are there any British proofs for example?
The initials could be the original barrel makers mark or the barrel strikers at Parker? Is the top rib marked "Laminate"? If so could the initials be for laminate barrels since Parker used various steels and would need to have a way to identify them before blacking? Originally barrel steel was sourced from England I believe except for plain steel and decarbonized steel.
Others could offer more help if we could see the elephant and not just its trunk peaking out from under the tent.
Erick