>>535366
The self-cleaning system used exhaust from the gas system to clean out any dirt and debris, which worked really well in theory but required a very specific powder that didn't generate much fouling. The problems started when some bureaucrat decided that "self-cleaning" means "doesn't need any maintenance ever", and got many times worse after the US decided to switch to a much dirtier powder (which also had totally out of spec burn rate and pressure characteristics, requiring a redesign of the whole gas system (thus ensuring that the people responsible for this change got kickbacks from Olin and Colt).
tl;dr it worked fine until the jews got involved