Yes. No proof what so ever and the one million rumor lives on. Two people on this forum have had the barrels from a pre-million time period and one has the receiver it came out of. There are probably more. Even Murray's book (Yes, I have one) constantly uses "(approx.)" liberally throughout the book when dating items. Curiously enough, I just noticed that the change to longer cartridges is mentioned. "a longer magazine carrier was adopted to accommodate the rimless...." Nowhere is making the receiver longer mentioned, a rumor that was on this forum many times.
Sorry, the rumor you are promoting that the 243/308/358 was discussed as having longer receivers needs to be verified. Can you provide links to a few of these "many times" that lengthened receivers were talked about?
