Here's a typical BSA made barrel for the conversion program----1954 dated. The barrel on my 1957 dated Mk1/2 is just like this one--1954--so there is still time for the machinery to be sold to Wah in the mid-fifties, even with the program lasting into 1957.
By that time it must have been pretty difficult to flog bolt guns in even the backwaters of the AK47 world.
Here's the proof off the same barrel, though----if this is just commercial work, why the military proof?
I admit to trying to read the section on British proof rules in "The Standard Directory Of Proof Marks", but it gave me a headache.
-----krinko
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