I don't really care for 5.56... there are better options with 6.5 x .308, 6.5 PPC, 6.8 SPC...
There are plenty of M-14 variants out today, and 7.62x51 is a proven performer...
I say it's time to move on from 5.56...
Thanks. Any particular recommendations for boat guns in those calibers? Bearing in mind that its primary purpose would be general self defense in a marine environment, including against pirates?