All really good info to know. As is with information regarding the military and production is un explainable mysteries do exists. For example my dad used this knife in Vietnam in early to middle of 1968 ending one year later in 1969. Was the only weapon he brought home with him as he told me while flying it always dug into his back.
So what do you think? Could it be possible these disc are died from the russet brown?
Is it possible that the discs were originally russet or ox blood and then dyed black? Yep. No telling what it looks like in person vs what shows up on my monitor.
Could it be black only but made before the 5/10/70 date that Camillus started a new manufacturing card indicating that was what they were doing? Also, yep.
We're going on what is KNOWN based on WRITTEN documentation. Since 03/04/68 was the date the specs changed, the change could be implemented any time after that when another run was made - IF Camillus' disc supplier had made the change. Camillus contracted out the disc making to Standard Washer and Materials, Inc. How many fungal treatment ox blood discs did they have on hand before they started dying them? No one knows.
If your dad got the knife in EARLY 1968, it would almost have to be dyed black over ox blood, as the change did not occur on military paper until 03/04/68. A mid-68 acquisition could have a "originally black from the git-go" if the black washers were available almost immediately from SW&MI.
Could the discs have been available that quickly? Again, yep. The military procurement people would have been talking with the manufacturers of (everything) prior to implementing any changes. It would have been simple for Camillus to tell SW&MI "Hey, dye those puppies black from now on. There's a change coming."
It could be that the change was implemented for quite a while before the S-card was modified.
If you could get the exact date your father reported to Viet Nam, that would put a NLT date for acquisition because he would surely have had it in his possession prior to getting there. Then if it has black only discs, that would provide us with an anecdotal data point in the determination of when Camillus started using black discs.
This exemplifies the exilhiration, fun, frustration AND intrigue of knife collecting. Little things coming from nowhere opening up new possibilities.