The M-16A1 lasted 15 years before its first major modification - I know, the Army gave me one in 87, then saw the A2 come out. Went in the Marine Corps and was handed an A3 in 90-98; got out, came back, A4 in 2006, and M4 in 2007. There's also a suppressed version. So that's at least 6 variants in a relatively short time. Post Nam, pre Gulf War I it was perfect for the "peacetime" mission, but once we hit the desert annoyances became issues. Then Somalia, Bosnia, Afghanistan, Iraq ... the platform and the caliber are ok for garrison duties, but limited in the combat arena.
But you cannot separate the platform/caliber from the wetware - the nut behind the trigger. The M16 was ostensibly developed with the wetware in mind. If you track all other relative statistics we have larger percentage of females, much lower physical fitness standards. In 2009 mental health visits outnumbered childbirth & pediatrics, way outnumbered wounded/injured, and most of those were "stress" from folks who never deployed. So the least common denominator [average user] of the US main battle rifle TODAY as opposed to NAM is smaller, slower, not as strong physically or mentally (even after entry level training), not as fit, less likely to have any firearms familiarity, but more likely to fire their weapon at least once in their tour of duty outside of training. We also fire more frequently with acute declination and inclination, which very few shooters understand ballistics. We gave them 4x optics because we found them less likely to take shots past 100yds with iron sights, but the optics are very rarely BZO'd.
Now a few of us on here have been with Infantry so you might say, not true! One, I'm talking across the entire military, and two I've watched the combat arms community lower standards over the past 23 years. I started out as a machinegunner with a 60, just glad I didn't get the mortar team, and I got pretty good with it so when I go to the ranges now and watch the 240 gunners or the SAW gunners I know what I'm looking for. Over on the KD range, marksmanship with the M16/4 is creeping downwards - fewer experts, more unks. But we take them out to combat anyway.
Anyone on GBO should attest to the fact that handing a poor marksman a better more expensive weapon is not going to inherently improve effectiveness. And if that marksman is in poor health (in every aspect of the word) it just makes it worse - fatty runs 1/4 mile from the back of the stryker to cover with her ppe on, dehydrated, kidney stones and bubble guts, breathing like a steam engine, scared as all get out, I want her armed with a bomb proof platform with a short range large caliber projectile. When she gets back Fobbitown she'll be more worried about skyping her boyfriend than weapons maintenance - its a fact. Let the "shooters" carry the longer range guns; they know what distance and angle can do to a trajectory. The one gun fits all mentality is silly.
