Find someone that has Military experience, they will show you the proper way to clean an AR. Also, is best practice to clean soon after you shoot, cause carbon is not good for a any weapon. Unless of course you have paid good money for either chromeed or titanium nitride or nickel boron treated parts? Anyhow with experience at cleaning an AR, you can get done in under 2 hours. Compressed air cans work great to get sand and grit out out of the trigger well and a Bore Snake is very handy and very quick.
Word of caution on asking someone in the military...make sure they are Infantry!
Here's what I do and I never have a FTF or Fire!
Use a CFC free brake cleaner and spray down all parts and the gas tube and let sit for a few minutes. Make sure you have proper ventilation and are not near any open flame and DON'T SMOKE!
Use a gas tube brush to rod out, bore brush the barrel and use a chamber brush that will clean out the feed ramp area as well as the groves in the bolt area of the chamber
Use a bottle of compressed air or air compressor to blow off all areas until dry.
1. Order a bottle of MiliTec1 Link Removed
2. Apply Militec1 as per directions found on website
I have done two apps on my upper and lower per directions. I usually fire between 200-300 rounds per session and find hardly any build up of carbon. After shooting I apply Militec1 liberally and wire brush barrel, gas tube and the feed ramp and bolt chamber and bolt and let it ride.
Same as above... but I use M-PRO 7 to clean... Non toxic, no harmful vapors... Get some long "pipe cleaner" style gas tube cleaners. Soak 'em in the M-Pro 7... I clean after each range trip because it's like therapy and relaxes me. 100-200 rounds usually between cleanings..
Only thing I have had a little trouble with id the gas tube, I use some foaming decarbonizer,(can get at auto parts store) spray the tube a couple times and its sqeeky clean, then as said prev on the action, bore and other parts
The outside of the gas tube is visible when you remove the stock however you pull the rear pin out of the lower and open the upper from the lower and and at the back you will see a shiny quarter size piece with a pin at the bottom the pin is spring loaded press down and the buffer spring and components will come out clean the inside of the buffer tube the spring and plug lightly oil the plug and reinstall opposite.
I hit mine with Gun-Scrubber after every use. Spray it out from the reciever end then run what looks like one of the longest pipe cleaners you've ever seen right down the tube then spray it out again with the Scrubber. All of this is done muzzel down of course.