http://www.orisonmarketing.com/pistonkleen.html?gclid=CIqrjIbc87YCFUzhQgodRnwAZQA 1 1/4" ball end mill works too. Also, a needle scaler works well, if you have compressed air available.
My kit came complete with a booster with a layer of carbon. I never thought about it until I fired it the first time and decided to clean it. A five minute project turned into an hour and a half. I started with the normal bore cleaner and kept coming up with more carbon. I tried a wire brush to loosen it up and I think I even used sand paper. I think I then put a bronze wire wheel on an electric drill before I got it all out. Obviously years of accumulation that no one thought to remove. I think if you clean it each time you shoot it it would not require that much work probably no more than a bronze wire tooth brush and bore cleaner.Any suggestions on other tools/methods to remove buildup if someone doesn't have one of these tools?