I’ve long felt that the AR-15/M16 were too fragile, temperamental, and difficult to clean for my tastes.
If you want to do a good job cleaning them, you’ll need a bright light, a dental mirror, and some dental picks.
Clean mine the way I was taught and never had a problem. No dental mirror required.
Amen to that. Buy a Mini 14 and spend the money you save on ammo. Especially the cheap lacquered Russian ammo that most ARs choke on but a Mini will chow down all day.