1. This is an airsoft site, and I believe the cp99 is an airgun. In future you will probably get very little help with any Airgun problems you may have.
2. Furniture paint stripper probably won't do the trick entirely, so you will have to do some hand sanding. I did a 1911 barrel a long time ago just using progressively higher grit sandpaper, then applying metal polish to it. I'm sure you can google up a much more comprehensive guide if you need further guidance.
Not for glory, nor riches, nor honours, but for freedom alone, which no good man gives up except with his life.