The U.S. military is currently, as it always is, researching better weapons designs and calibers.

I'm not a fan of the M16 or M4, but they have not been as bad as a lot of people make them out to be. The last attempt at replacing the current weapon with a .308 FN/FAL lookalike failed reliability tests. Testing continues.

That being said, remeber that to replace a service weapon is no easy task. Even if they decided on one tomorrow, it would be 7 or 8 years before if became the standard. It took something like 9 years for the M16 to become the standard service rifle for all branches. In Vietnam, there were several Marine Units that never got them until the war ended.

I'm sure there's a lot more to it than one might think. I think we will see a replacement sometime soon,but I doubt it'll be a .243.