I have two 6.5mm CMs that are supposed to be shot out but they still shoot just a good as they ever have.

My 12 LRP has over 4200 rounds down the barrel.
My 12 FV has over 3000 rounds down the barrel.

I don't shoot hot loads but I expected them to be shot out by now, but they aren't.
I also clean out the copper after every 100 rounds - a normal range session for me.
I use Wipe out or Patch Out each time I clean it.
It is not a severe copper cleaner and won't harm the barrel if you leave the barrel to soak overnight.
I leave it in for an hour usually, and since I use it regularly, it does the job.

It is possible that I don't shoot well enough to see the same degradation that a superior shooter might see.
However, for me, the accuracy is the same as it was when the barrels had 100 rounds through them.