Dave, I understand your frustration, but... I believe it is a mistake to tar all AR15s with the same brush. Given, they are special purpose. Given, they are NOT for everybody. Given, they are not the best military rifle on the planet.
But... you said you bought 4 Bushmaster AR15 clones. If you bought them all at once I understand but if you bought them consecutively after learning the first was a POS, shame on you. There is no other civilian AR15 on the planet beside the Colt, pre-ban, imho. I have heard a thousand reasons why people would not touch a Colt with a ten foot pole - non mil spec. (What IS milspec, anyway??) If it ain't full auto, it ain't mil spec, anyway. Politics, caving in to clinton, yada yada. Strangely enough, the guys who buy other than Colt for all the sundry reasons always have "problems" with their Bushmasters, Olympics, Armalites, DPMSs, and whatever other clones they buy or assemble from parts in little baggies with no identification.
Similarly with magazines. If you have a military contract magazine that is undamaged, it will feed until hell freezes over. I have never had to discard a used Army mag, preferably marked Colt, but also Okay, Adventureline, Parsons, and others. The green follower hokum is something cooked up to make a out of spec military contract mag work. I belive it applies to Sanchez and maybe one or two more brands. The mags should not have been accepted by the military inspector, but destroyed. You will never have a problem with a metal or black follower 20 round or 30 round mag of the brands I've named. Frankly, I believe that that's the problem with cottage industry AR15 clones, too. The military inspector rejects parts which find their way into your Bushmaster, Olympic, DPMS, or Shotgun News Special.
So I say again, there are AR15s and there are AR15s.