As far as SAL/CAL is concerned, what was disposed of, apart from employees, was probably just excess machinery and office equipment, and IRRC what I think I read, the machinery was mostly moth-balled. This was the Cold War after all. ;)
The parts, jigs, tooling, drawings etc. etc. all stayed, naturally, since they continued to manufacture No4s at a slower rate, as well as various other things like the Canadian EM2 etc. There were hundreds of NOS 1955 Long Branch receivers around a few decades ago, albeit with the last digit struck separately, so work continued.
It would have made no sense to dispose of No4 parts; it was still to be our service rifle for over a decade. We've seen evidence in other made-up rifles that parts that were slightly defective and no doubt 'written off' as a result were put aside for possible use later. Same thing happened in other factories: about ten years back Sarco or one of those places had a run of original No5 flash hiders: not repros, originals. Perfect in all respects except the bores of the cones were slightly misaligned. Some sensible person decided there was no point throwing them away after public money had been spent on them, when they might be useable or repairable later.
It's 60 odd years ago, but there might be a few SAL/CAL people still around who could confirm these things.
Your rifle does appear to have the maple leaf proof mark on the barrel and what other rifles does that show up on? Definitely the 7.62mm 'DCRA conversions'.
If there are other markings you have found please post photos of them.
Instinctive scepticism is not a bad thing! ;)
