Member StrangerDanger here has posted several times that, as an experiment, he once went like 15,000 rounds with one of his M4's without cleaning it, other than squirting the bolt and receiver down with CLP or the like, and never experienced a problem.
Latest evolution of my M1014:
Carrier Comp Ti mag tube ceracoated midnight bronze (they coated the 3 position recoil tube as well).
Briley match trigger and loading port work
TTI lifter
GG&G Charging Handle
GG&G Bolt Release
Scalarworks Mount
Trijicon SRO
Daves metalworks safety
IWC light/sling mounts
Stippeled fore grips by Tango
BF vickers sling
As for myself, when I first got my M4, I tried cleaning the barrel of lead streaks and melted plastic with kid gloves. I found it to be an impossible endeavor. After wearing myself out and wasting a lot of time trying to clean the bore, I read about using a bronze brush, a length of rod, and a cordless drill.
I don't waste time anymore.