I went to PI in June 1962. We were issued brand new M-14's out of the crate.
A guy at our Gun Club once claimed they were the first PI Platoon issued them in August of 1961. I figure that's correct because some local guys went in as a group in July 1961 and they used M-1's. We had a Mini Reunion a few years ago and one guy had their Parris Island Book for the rest to sign. There were pictures of them using M-1's.
Ahhhh ... the M-14. "Finest battle implement ever devised by man." MY Quote.