Re: 22-6mm barrel
Yes, too much. Are you FL sizing after each firing? No need to on this one; that may be part of the problem. What I do with mine is use a fireforming load of 4895 beneath a cheap bullet seated firmly into the lands and then neck size after that. Every three or four loadings I'll run the brass into the FL die but have it set to just bump the shoulder back. I think you'll find your brass life greatly increases.
As to the coppering, nature of the beast with tiny bores, fast twists, and high velocities. Do a good break-in and cleaning will usually be easier, but even with that mine still copper fouls a little faster than some of my other rifles. With your extremely fast twist for this case size, unlikely that will go away.
Great cartridge, but definitely a little fussier to feed & care for....