From marinecorpstimes.com: “Marine leaders have made the momentous recommendation to ditch the iconic M16 in favor of the M4 carbine as the new universal weapon for infantrymen. The recommendation to swap the venerated rifle that has served as the grunt’s primary implement of war since Vietnam now sits on the commandant’s desk, pending his final review and a decision. But, the swap appears imminent and if approved will relegate the M16 to a support role. It follows a similar shift already underway in the Army.” The move favors the shorter M4 for its CQB advantages in tight situations . . .
In the words of retired master sergeant Larry Vickers,
“Some argue beyond that the M4 carbine lacks effectiveness versus the M16, but the M16 is like driving a sports car with a six-cylinder engine,” he said, because it is limited by the same small 5.56mm cartridge as the M4. “You can shoot 400 to 500 yards away, but you are still shooting a 5.56.”
A longer barrel would make sense with a heavier hitting round like the .308, but unless Marines are given a larger caliber Vickers said the M4 is “bringing so much more to the table.”
“It is the world’s gold standard,” he said.