Retract the charging handle and remove the bolt carrier and handle
With the rear of the upper receiver hinged open or separated from the lower, you can now retract the charging handle about halfway, then pull rearward on the bolt carrier and remove it from the receiver.
With the carrier group removed, you can retract the charging handle until the tabs on the sides of the handle align with the cutouts in the upper receiver, drop the charging handle down into the larger opening, and remove the handle to the rear.
Disassemble the bolt carrier group for cleaning
On the left side of the bolt carrier about halfway back, you will see the head of a “cotter pin,” the correct name of which is the firing pin retaining pin. Pry this out with a suitable punch or the tip of a bullet (you may be able to use your fingernails, but probably not) and remove it. This frees the firing pin, which will drop out of the rear of the carrier group if you knock the back against a wooden/padded surface.
With the firing pin out, push the bolt into the carrier, and then the bolt cam pin, which has a rectangular head, can be rotated 90 degrees to clear the bolt carrier key and removed upward out of the carrier. Then the bolt can be pulled from the front of the carrier.
Spray the bolt carrier group parts and the receiver extension (star chamber) with solvent, and brush them clean
With the bolt carrier group disassembled, spray all of these parts with a suitable carbon fouling solvent. Clay recommends Otis cleaning products. Also spray the “star chamber” or barrel extension behind the chamber, as this area can get quite dirty. Let the solvent work for 10-15 minutes.
After the solvent has had time to work, brush, wipe, and/or scrape the carbon fouling from the carrier parts, including the bolt channel in the front of the carrier. Clay likes the Otis B.O.N.E.® Tool for effectively removing carbon buildup here. A nylon brush or old toothbrush works well for cleaning the exterior of the bolt carrier, bolt, cam pin, and star chamber, though Otis’s star chamber cleaning tool makes cleaning the nooks and crannies of the barrel extension quick and easy, in just a few twists. It features a parkerized steel scraper to remove fouling build-up and felt cleaning pads to pick up the fouling loosened by the scraper.
After all the bolt carrier parts are suitably clean from fouling and debris, wipe them all down with a soft rag and apply the oil or protectant of your choice, then reassemble the bolt carrier group in reverse order. (Insert the bolt with the extractor to the right, insert the bolt cam pin and rotate it 90 degrees, pull the bolt forward, insert the firing pin from the rear, and reinsert the firing pin retaining pin.)