I'd agree with much of the original assessment.
I operated as the "Ma Duece" (or "Ma Deuce" I've seen it spelled various ways) gunner on a "gun truck" (5-ton dump truck with bolted on untempered boiler plate for armor) for convoy escort many times, and I luv'd that big heavy pig. Never failed. Operates more like a small block engine than a mechanical firearm.
'Course, finding ammo was always a problem.... only issued 200 rounds in Kuwuit (basic load is 1,000 to 2,000 rounds depending on MTOE), and managed to barter and beg another 600 rounds from various sources, but still not great if I'd have gotten caught in one of those notoriously long firefights while I was in-country. 30mm grenade launchers (Mark-19 and 203) only had a (very) few rounds as well. Lubricant usually came from cans of WD-40 more often than not. Cleaned it a couple times using oven cleaner.
The M-16 I was issued came "
new" with a bent barrel. Had a Colt AR-15 scope for it that I never could get to line up with impact point quite right. Iron sights were completely maxed out, Colt sight did not have that much adjustment in it (guess they'd assumed it'd be put on a straight rifle.....). Piece of junk, which I mentioned...often...and loudly... to no avail. Never fired it in anger while in-country......the Ma Duce, OTOH......
All rifles had basic load of 220-230 rounds (nobody completely fills a 20 or 30 round magazine if you want to avoid another potential source of jams) .....but no additional bandoleers of ammo were available to us.... again, our SOP was "shoot and scoot"...we couldn't stay to put up a sustained fight no matter how much we wanted to.
SAW (243), two options for us for the belt feed...100 round soft-side bags, or 200 round "porkchops" (plastic drum).... gunners kept with the 100 rounders because the 200 rounders jammed so often (probably the weight of additional rounds working against the feeder during operation), and the porkchops were hard to wield in tight areas...and could break, split, or get knocked off the weapon. 'Course the fabric bags could wear out too.
This was all during OIF-II. You would see all sorts of jury-rigged vehicle mounted systems. We'd raid former Iraqi Army arms rooms and deal with black marketeers to acquire Soviet (and later Russian) era weapons and ammunition.
I saw Iraqi armor taken from BMPs attached to our vehicles. I saw a nice Soviet-era NVS "utes" mounted on an American HEMMET "gun truck" rig. Also saw a wheeled anti-aircraft/armor gun being hauled off by a group....offen wondered what they managed with that. Makarov and various Czech pistols were not uncommon sights. Turrents, pintal mounts, and blister shields from Iraqi armor vehicles were sought after for conversion to mount our weapons systems onto vehicles that did not normally have them.
We kept a decent RPK with 5 drum mags in the back of our "gun truck" in case my .50 or the 243 gunner ran dry on ammo, or seriously jammed, during a fight.
as to 5.56 vs 7.62 and .45ACP vs 9mm endless argument. A lot of it is perceptions, and the actual environment has a lot to do with how a round will perform in the real world vs a "lab" environment. Many opinions exist on the choice of these rounds.
5.56 is lighter (carry more --- if issued enough to begin with

) and will usually travel further in open spaces, and as a tumbling round can do serious damage (or light damage...tumbling rounds are unpredictable)....but M16 and its variants are maintenance wh***s in desert environment.... not reliable, even with good maintenance, if you get caught in a dust storm, or hauling a** down a unimproved dirt road over there before or during fight. That talcum-like dust gets into everything. After a cleaning, yes it will fire well. 5.56 round also typically spins off the first thing it hits, so lousy in heavy brush. The 5.56 cambered in a weapon that could handle a dusty, desert environment would perform very well indeed.
7.62 normally has shorter ranges, more "kick" (accuracy problem for some soldiers who are gun-shy --- not all of us grew up hunting or doing range target practice), can usually bull their way thru brush and scrub to find their way to target, usually more knock-down and penetration power, result in heavier basic load. And it sounds a whole lot more intimidating than a 5.56 being fired....but then there's the difference in outgoing and incoming rounds to consider. It will also penetrate car window glass a bit easier.
9mm Para sucks as a combat round. Okay for city SWAT and such due to not puttin gup with overpenetration and hitting innocents, but as a battlefield round it sucks.
.45 is a classic, but my personal choices run to the .40 cal and (especially) 10mm (basically a .40 cal Magnum)
A lot of reasons military went to lighter NATO rounds. Compatability with NATO. Lighter rounds tend to "wound" not kill, and the wounded soldier usually requires (ideally) 2 soldiers to take him from the battlefield --- effectively removing 3 fighters with one round (so sez the doctrine at the time). Idea that you can carry more of the lighter rounds weight-wise.
That is for a "more civilized" battlefield ideal. Not good having pea-shot when dealing with radicals, berzerkers, or guys hopped up on drugs coming at you in human waves or with several pounds of explosives strapped to their chest. You want to put them down NOW. Permanent-like. Similar to reasons U.S. Army first adopted the .45 in 1911 in the first place.
I'm in the bigger is better camp.....then again, I'm also a Ma Duece gunner.
