It’s better than the M4, but you can’t have one

Wish I'd had one of these when I was in.

I had an M16A2 when I was deployed in Iraq, and had carried or maintained it or the A1 as a unit armorer for over a decade before. I came to the opinion that the M-16 series is wonderfully easy to shoot, reasonably light to carry, has sights highly useful to a skilled shooter/highly confusing to the average soldier, horribly sensitive to fouling, and a true bitch to clean to military standards. I've used more cans of carburetor cleaner than I can count to clean them once I figured out that it took hours of scrubbing and scraping to get enough carbon off the bolt and bolt carrier to get the armorer to accept it (when I wasn't the one doing the accepting). I've seen soldiers who are ardent hunters or have never handled a gun outside the military try to overcome fouling and jamming by saturating everything that moved in CLP, not using any lube at all, and lubing just the friction points. And I've experienced that joy of tweaking that damn gas tube back and forth for an hour or two trying to get the bolt carrier to close on the gravity tilt test listed in the armorer's manual when someone would complain about their malfunctioning rifle.

Meanwhile, my privately owned cheapo Chinese SKS and Century Arms L1A1 would just keep chugging along round after round.

I think a lot of that came down to two features: direct impingement gas vs. piston driven systems, and seven bolt lugs rather than two (or mechanical tolerances relative to fouling).

While changing bolts and receivers essentially requires replacing the entire rifle due to costs, I think the M-16 series could be upgraded with new upper receivers or receiver mods to make it financially viable in the long term.