This is the Argument Room

It looks like they are looking at replacing/upgrading the M4 carbine again.

As a result of stoppages and other problems under very heavy use, they are looking at some mods:

Army weapons officials presented the proposed changes to Congress on Oct. 30. They are:

• Adding a heavier barrel for better performance during high rates of fire.
• Replacing the direct-impingement gas system with a piston gas system.
• Improving the trigger pull.
• Adding an improved rail system for increased strength.
• Adding ambidextrous controls.
• Adding a round counter to track the total number of bullets fired over the weapon’s lifetime.

I think that the gas tube operation has always been a problem, so going with a piston makes sense, and an improved trigger pull, making the weapon a bit more robust, and adding ambidextrous controls are all pretty common sense. The heavier barrel is a trade off, more weight vs better performance under heavy use, and I don't have the data for that.

As to the round counter, it has to be designed such that if it fails, everything else works, because it add a lot of complexity.

To my mind, the real solution is to go with a Bullpup design, which would be shorter, but have a longer barrel, and you can incorporate improvements in a new weapon.

That being said, arguments over the M16 family, and 5.56mm rounds tend to be contentious.