No one is trying to change the history of the first AR's issued in the 1960's. There were problems with 1) dropping the 35 year old requirement for a chromed barrel, 2) the 30 round mag, which still has to deal with flimsy construction, weak feed lips, and sticking followers in a curved design used in a straight mag well, 3) early issue powder that was repurposed excess.
And there was the production ramp up which got an outside contractors tight chambers literally replaced in the field, sometimes within eyesight of combat.
Today, very little of those problems exist, anymore than a 66 Mustang is the same as a 2010 Mustang. The detailed improvements are well known and frankly, beyond reproach. Bluntly, questioning the bolt and extractor is out of the loop - they've been addressed, what is a problem is overgassed 16" carbines opening too early, a commonly acknowledged problem in some guns. It's the entire reason midlength gas exists, carbine is for 14.5" military barrels, midlength is for civilian legal 16".
Heat is not a problem. I say again, heat is not a problem. Simple heat temperature studies are on a lot of forums. Using a infra red detector, temperatures have been recorded, with a baseline issue type M4, piston gun, and others. What is recorded is the bolt carrier temps are about 40* warmer than piston. You can shoot full mags, shotgun the bolt carrier and hold it with bare hands. You CANNOT do that with a piston gun - apples to apples, grab the gas piston chamber on the barrel after a full mag and see which is hotter. Actually, don't, it exceeds 500*.
DI AR's don't have substantially higher temps, if anything, the Stoner gas piston runs dramatically cooler in the bolt carrier than out on a barrel. Bolt temps are nearly the same, as they get warm because the brass cartridge head is the only contact. Chamber temps are nearly the same, and so are barrels. No reason for them to be different.
The major problems with combat firearms are magazines, bad ammo, and environmental contamination - almost never gas residue, as AR's are commonly accused. In one test, Mike Pannone ran with with no lube through more than ten basic loads of ammo, 2.400+ rounds, before gas residue became a problem, and lubrication immediately solved it for another few magazines. Soldiers in daily combat, even training, will perform daily maintenance at a minimum, especially once before going out of the wire, and don't let a weeks worth of hot combat disable a weapon because of their negligence. As an aside, the weapon will malfunction from excess barrel heat in full auto fire long before residue is any problem at all. Hence, the M4's no longer have M203 barrel cuts. That causes problems, not BCG temps.
The majority of complaints about the AR are either not understood or are complete falsehoods unfounded in any serious examination of fact. I understand it doesn't change the results experienced 45 years ago, but that perspective also allows looking at previous designs like the Garand, which also killed young men because of it's initial design flaws. What's different is that we now live in an information age, and a lot of it has to be sifted. Anecdotal stories of "guns than kill" are rarely sorted out for a real cause, we just blame the weapon. Never the operator - out of a societal sense of being nice, which is sometimes not deserved or accurate. We don't like to accept humans make mistakes, and testosterone influenced humans even more so.
DI runs just fine, if someone want's to disable the working piston in the BCG and add another on the barrel, it's their money, don't create false reasons for it.
