The M16 has been undergoing some kind of "fix" ever since Nam. When will it finally be seen it sucks? Dump it and find something that works. Even the AK was head and shoulders above the M16.
If the .223 is not working, use what does, 7.62x39 is a man killer. Use it.
For what we will waste on R&D over the five or more years to find another platfrom we could buy AK's and save money.
We have some of the great minds of the 15th century running things.