Use 400 to 600 to 1500 grit wet or dry sandpaper that's used for automotive finishes. You might want to also polish the top of the hammer where it rubs against the inside of the slide. CZ's are fantastic handguns, however there are a lot of tool marks on the bearing surfaces. Depending on your skill level and confidence you could also polish the frame rails on the slide and frame if it is an all steel frame. I wouldn't polish the rails on an alloy frame though unless you really know what you are doing. CZ's at least the ones I have, have fairly stiff firing pin springs, another reason why I wouldn't recommend changing to a lighter hammer spring. You can make a polishing block from a piece of styrene plastic about 1/16th of an inch thick, 1/4 inch wide and an inch or two long to wrap the strips of sandpaper around, this will give you a flat surface. You can purchase styrene plastic from hobby stores in different thicknesses and it can be easily cut with a straight edge and "Exacto" knife or other sharp instrument. I've never had any issues with the CZ's I have straight out of the box. But I have polished many semi auto's using these methods as they reduce the amount of friction on the bearing surfaces. In a way you're kind of breaking in the gun without having to fire hundreds of rounds through it. CLP means "C"leaner, "L"ubricant and "P"rotectant, it is not meant for polishing.