Copper fouling from copper jacketed bullets. Absolutely normal. And it is a booger to get it out sometimes. In handguns, it's not real critical as far as accuracy goes. You scrub it out and as soon as you fire it again, it's right back. In extremely accurate rifles, such as Bench Rest long range, or Sniper style shooting, those guys try to keep it down to a minimum w/ copper fouling removal products. Past a certain point, enough copper fouling can hurt the fine accuracy of very "tuned" rifles. But hand guns, no. If you can see an extremely heavy build up of copper after a lot of shooting, then get a copper fouling removal product from your local gun/ sporting goods store and remove it. Usually most handguns only foul to a point and then just don't get any worse. The more you shoot, the smoother the rifling gets. Just like a car engine, parts wear in and further wear goes down to a minimum. Most modern handgun barrels can handle well over 10's of thousands of rounds before being worn to the point of accuracy degradation.
Scrub it out w/ Hoppe's #9 and forget it. Won't hurt anything.
Have fun and be safe.