Let me start out this post by just saying this.
Never, not once, dirty, clean, dusty, snowy, muddy, wet or dry did my M-4 fail to go "BOOM" when I pressed the "BOOM" switch. It never jammed, double fed, stove piped or just went "CLICK."
That is what I tell my partners (who are gun guys who like to spend hours debating the minutiae of caliber, tactics etc.) who ask me about the use of the M-4/5.56 combination in combat. I tell them it is like having a super model girlfriend; she will get dirty with you, but she's got some rules, and one of those is that you better treat her good afterward.
It never failed me, and it always placed the bullets where I wanted them to go. I found that some carb. cleaner down the gas tube (to dissolve the carbon buildup--DEFINITELY not in the dash 10 manual), a bore snake through the barrel and a wipe down of the bolt was all I needed after any patrol to get it back to normal.
I bring this up because it appears that the specter of another round of "But does it work (insert unique operating environment here) based on the design?" with the US Army once again in the midst of a battle over whether or not the M-4 is a viable weapon for use on the battlefield.
I can carry a poop-ton of ammo for it (which you may need), it is easy to use, simple to operate and at least in my case, was rugged enough to last a year in combat without breaking any parts and got the job done.
The first thing any leader will tell you is that in combat, the rules in this order are; weapons maintenance, equipment maintenance, soldier maintenance.
I will conclude this with an idea for the US Army, which is; no gun is going to solve all the problems of weight, accuracy, ruggedness, reliability and stopping power because in order to get one, their has to be a sacrifice of another.
The M-4/M-16 combination has been making live enemies into dead corpses with the aid of the skill of American soldiers in rifle companies for quite a long time.
Before departing in another direction with the development of more whiz-bang battery powered doo-doo that will fail the first time a private drops it off the back of Deuce and half, make sure to capture all of the lessons learned (good and bad) from soldiers who have used the product in combat and not from the contract rep. from ABC Arms Factory.
Chose wisely... Lives depend on it...