I consider a gun clean when accuracy is restored and the gun functions reliably. You can clean a gun for 5 or 6 hours and there will still be some small amount of fouling left. Fouling gets into the very smallest metal pores and is hard to remove.
I clean my gun bores until the patches come out light gray and the action functions reliably. It takes me about 15 minutes to clean my Glocks. I soak the barrels with M-Pro 7 gun cleaner for 10 minutes and then patch. Done.
Remember….a absolutely clean barrel will not be accurate. It takes a few fouling shots before most barrels are accurate. Just talk to a bench rest shooter.
Learn how to field strip and reassemble the Ruger SR-556 piston rifle from a Ruger professional. It’s very similar to most other AR-15 piston clones. It’s much easier to learn from a video than a gun manual, for sure.
Always use a good gun cleaner and gun oil in order to make the most of the AR-15’s reliability and accuracy. I highly recommend M-Pro 7 Gun Cleaner, Hoppe’s Elite Gun Cleaner, Mil Comm MC25 and Slip2000 725 Gun Cleaner. As far as oils go, I recommend Rem Oil, M-Pro 7 LPX, Breakfree CLP, Ballistol, Hornady One Shot and Hoppe’s Synthetic Gun Oil…just to mention a few that did well in my gun oil testing.
Learn how to reassemble the Marlin 336 lever action rifle from a professional gunsmith at Brownells. This method applies to most lever action rifles, so if you have a Winchester, it’s basically the same. Remember to use a good set of gunsmith screwdrivers whenever doing maintenance on firearms. A stripped screw will ruin your day.