Mystery RSAF Barrel fitted to Envoy

[Lance]

Greetings All

I am up to the RSAF Enfield's Envoy chapter and finally looked at my example, which gave me a surprise. I hope a few of you with more experience might have an answer or an idea.

After removing the handguard I expected to see a '69 or '70 dated BB306 or CR1470 Enfield type barrel, but I did not. It does not have the nock/knox form with the only mark being a fancy RSAF stamp and a sold-out-of-service mark.

The barrel markings suggest it is the original barrel fitted to the rifle which was made or fitted at a RSAF. Is it a trials barrel that did not make the cut and was fitted on a commercial rifle just to use it? Any other ideas?