If all that copper was smoothing out/filling imperfections in the bore, it may shoot worse now that it is all removed. Every barrel needs some level of copper fouling- which is why no one removes copper and then takes a cold bore shot that needs to "count". Some rifles get back their accuracy after only a round or two. Others can take a couple dozen. Experiment to find out what works for yours...
The military no longer removes copper from their(sniper rifle) barrels until there is a drop off in accuracy. Every rifle is different, some need a level of copper fouling to shoot well- depends on the quality of the barrel.
Do a search, lots of discussion on this.