I think most of what Jason has are later run barrels but they should be compatible. I just fit a set of his barrels to an early graded ejector gun for a client and the ejectors were also the early style. Everything works. It is a huge job and the costs will far exceed the value of an average C grade 12bore. Best of luck with it.
Steve

http://www.bertramandco.com/
Booking African hunts, firearms import services

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