I always like to read the posts involved with .22 rimfire barrels, and how they SHOULD, or SHOULDN'T be treated.
.22 rimfire barrels, for around the last 50 years, or so, have been rifled by only two methods. Either button rifled or with a mandrill inserted and then hammer forged. The rifling groove to land height only runs from 0.0020 to 0.0025 of an inch. Been that way for a very long time. Some mandrills will even include the chamber and the leade when the barrel rifling is hammer forged & formed. That process provides for the chamber & leade to be almost perfectly concentric to the bore center-line.
When a .22 rimfire chamber is "reamer cut" into the barrel, the right-hand cutting action of the chamber reamer will most often create a sharp edge {roll-over burr} on the left side of the leade where it meets the bore. That sharp edge will indeed peel off lead shavings from the bullets diameter as the bullet passes over that sharp edge. It will take some time, but the burning powder will eventually burn that sharp edge off.
Some have tried to "fire-lap" that burr away using grit impregnated .22 rimfire bullets, and in the process have moved the leade forward a ¼ inch or more, and then blown whatever accuracy there was previously all to hell.
It was posted above that the person doesn't use a brush only to clean the chamber. A brush alone will not clean anything, a GOOD solvent left to soak in the bore,will though. I will only use proper size felt plugs and a modern solvent on my, or my customers, .22 rimfire bores. And then, those plugs are pulled through the bore using a length of weed-whacker line. The solvent is left to "soak-clean" the bore for 15 minutes and then, two dry plugs are pulled through to remove any gunk in the barrel. I save the nylon brush for the chamber and leade area. I own a bore scope also, and for .22 rimfire barrels, it gets used quite often: