Yah, there's some prefix overlap with BSAs. However, the first run did not all have the first digit "3" and only four digits total. With the second "A" prefix S/Ns went to five digits, but the first number was "always" "3". (So where's the exception?) Sorry for the delay in clarification, but it wasn't even an item that I thought of discussing and had to double check some references.
So, back to the weirdness.
Thanks for the various theories as to how this incongruity might have occurred. I bought this thing eight or ten years ago ONLY because it was a bit out of the ordinary. I also like the scope can and it's little "homemade" adjusting tool. With the turrets set per Captain Laidler's instructions, the tool works fine for fine tuning purposes.
ETA: added some more captions to the photos on the first page.
Upon the revisit the scope bracket was examined. The drama w/ Lance's second theory is that the bracket condition matched the scope much more close than the rifle. Granted, the brackets have a far different finish regardless, it's just that the "brown-ness" works well with the scope. Wouldn't rule it out, though, IF the scope assembly were stored separately from the rifle in a more humid environment.
I will do some more photos of the bracket rings screws.