First off, you don't need to use a 6mm caliber BORE brush to clean a .22 rimfire chamber. That size brush is
way too big for a .22 rimfire chamber. Here at
Sarona Gun Works LLC extensive experience has taught that the .22 rimfire bore brush will work excellently to clean a chamber and leade if you use the correct equipment. Try measuring the case diameter on a .22 rimfire cartridge and compare it to the dimesnions of a .22 rimfire chamber. Then, measure the diameter (honestly) of a .22 rimfire bore brush, and then compare those dimensions.
A .22 rimfire chamber can easily be cleaned with common sense, and using an "over-size" bore brush will only bend the bristles backward to where they do no good. We here, currently have an innovative combination
chamber and receiver brush with easily interchangeable brushes. Both of the nylon and bronze bristle chamber brushes can easily be changed. The end brushes are also brass and stiff natural hair bristles that will clean in and around the internal receiver areas. I am still testing various brush combinations that will keep the price point for this tool at around $10.00 to $11.00.
One thing I've learned over the years is to let the "solvent" do the job of softening whatever carbon build-up is encountered, but always, consider a wet patch through the chamber and bore right after a shooting session. That simple attention alone will prevent any need for scrubbing.