I agree theAR is one of the most easily accessorized rifles made but as a combat rifle it's one of the biggest p.o.s. ever issued.
Cooper's name has been mention, well the Col. also stated the M-16 /AR is a fine weapon as long as you 're not asking combat vets who arse 's were on the line that used the weapon. The only reason it hasen't been replaced as primary battle rifle is costs plain an simple.
New issue M-16 's need only to shoot 4" group at 100 yard to be acceptable for issue.
There are far bigger POS rifles around the worldthan the AR-15 ever was. The problem or perceived problem with the AR-15 is that it was testedby the end userrather than the manufacturer and it had some teething problems. Unfortunately, thebad reportsthat came back from some of the earlier issued AR-15sand the bad ammo that came with them have given them an undeserved bad reputation for at least 2 generations ofChairborne Rangers whomay have never even held and AR-15 much less owned one.
Col. Cooper, God rest his soul, I consider just about everything he says about handguns as near gospel, but I've never been a big fan of his ideas of riflery.
As for acceptance of AR-15 rifles that shoot 4 MOA- have you ever fired a M1 Garand with issue ball ammo? 4MOA is more of the rule than the exception. If there is such a rule as 4MOA acceptance of AR-15s, its probably on the very far edge statistically, and is not likely to be seen very often.