RE: Cleaning AR-15's
I have spent many a time cleaning M-16's in the Army, National Guard and Army Reserves and they take a while and a lot of elbow grease to clean thoroughly. Clean the barrel and chamber thoroughly, disassemble the bolt when cleaning, as it makes it much easier and make sure to have a good number of q-tips and pipe-cleaners on hand as they work well for getting into the small and tight places. I was used to only using CLP to clean them and know it does work, but just have to scrub quite a bit. I would not worry so much about thoroughly cleaning the trigger mech every time you shoot.
We used to take M-16's in the shower and ran under very hot water to loosen things up and then immediately clean adn lube to prevent rust.