Deer/bear hunting in 1968, then this would likely be the fall. By two Viet Vets? Then they were in Vietnam in mid 1968 at the latest.
According to a quick search, the M16 did not replace the M14 until 1969. I was there in Jan 69, carried the M14 and many units were being issued the M16 at the time. I specifically recall boarding a Caribou heading for the boonies seated by a butter bar and we had a discussion. He had just gotten his M16 and was not impressed.
Maybe some units were issued the M16 in 68, but very few. The author of this article could be confused.
My Dad served 3 tours in Vietnam and said the same thing. He wasn’t terribly impressed with the M14 either.
In my opinion, the M14 is still a better weapons. Just a lot heavier.
Range is not an issue with either of them. A lot more ammo is usually burned in a M16 vs a M14.
I digress, sorry. Anyway, it is possible they carried an M-16 in Nam in 1968. What I found odd was the idea that you went in a tunnel or cave network after an NVA or Viet Cong with an M-16. I know a former Marine tunnel rat. He had the bad luck to just barely meet the USMC height standards. He said the preferred weapon was an M1911. He said an M-16 would of been difficult to use in confined spaces. Side note, he became an EMT, joined the Navy Reserve in 2002, went to Iraq in 2004 did combat patrols as a Navy Corpsman with the Marines. Sounds like in this case, there was either a bit of hyperbole on the part of the Vets or the author.
Could the author have been having a beer with John “Deer Hunter” Kerry? If so, I think I know who ended up paying for the beer.