The problem with the original rifle design was not the engineering but was the very dirty ammo provided to front line troops.....The rifle was sold to the troops as self cleaning and not needing field cleaning which got a lot of soldiers killed because their rifles jammed up in combat....Later ammo was of a different powder and cleaner burning which didn’t clog up the rifle.....All firearms need to be cleaned and maintained even on the battlefield but once better, cleaner burning ammo became available the problems with the AR rifles went away.....