When I was enlisted our M16s were either Colt or FN. The consensus seemed like the FN was a better gun. But the issues that came up with any of the guns tended to be from the abuse that comes with extensive dry firing (bad firing pins) and crappy steel magazines (poor feeding). Worn extractors were another common problem.
With all the M16s and ARs that I’ve experienced, I could never tell a difference between the parts or quality. I’ve never fired a high end AR, so I don’t know what I’m missing, but none of my lower and mid grade ARs have given me poor performance.
The 1000 rounds of ammo in a day might be a good torture test, but that’s what it is, a torture test. I’d be curious to know if anyone shoots that much ammo through their AR or M16/M4 in a day in a combat setting. I can’t imagine that shooting 1000 rounds during a day in real combat would be conducive to a long life.
My experience has been that dirt and carbon buildup are the crux of the AR/M16 design. You have to keep them clean. Maybe the more expensive AR handles grit better? I don’t know. I do know that if I fire 500 rounds in quick succession, starting with a clean gun, things have worked out fine. But if I fire 200 and let it sit over night, all bets are off.
