I've always liked the M-14, when I was in the Coast guard that's all I used. Of course we trained in boot with M-16's, once aboard ship when I qualified to be on the MLE (Maritime Law Enforcement) team I got to choose the 14 or the 16. Out of 2 boarding crews of 12 sailors apiece, only an old chief gunners-mate and I chose to use the M-14, everyone else chose the M-16.
When He asked me why I chose that rifle over the new fancy one, I told him my uncle who served in Vietnam loved his, owned a couple of them and that's the rifle I learned to shoot and hunt with when I came to live in the US permanently at 15. When he prodded further I told him I didn't like the M-16, it felt like shooting a .22 and I wanted to be sure that if I had to shoot someone, one shot would put them down (no offense to the M16/AR-15 owners) Because we all know that firing at static paper targets with proper form etc. is easy, no quite as easy when the target is moving and firing back at you, so even a marginal double tap or hit with the 7.62x51 / .308 at close range is gonna do enough damage to keep em down. A firefight on a ship is a lot like CQC in a building except you've got no possible escape route besides diving overboard.
Joe