If you detect copper in your bore then you should remove it. Some barrels and cartridges tend to buildup copper more then others. Some good custom barrels build up copper at the first several shots and rarely build up copper after. I find that using Wipeout tells me whether there is copper in my bore. I also find that it takes a bore a long time to be copper free using Wipeout. Its a great product since it eliminates a lot of brushing just not as great on a heavy copper build up. I then will use Shooters choice copper cleaner or Sweets to remove it. Once a year I run my guns thru a Outers Foul OUt III if they have a propensity to copper up.