Working on a Sig P938. Recently got it back from having it cerracoated (sp?) and its not always extracting the cartridge after it fires. Sometimes it does, sometimes it doesn't. Its seems that there is not a lot of tension in the spring so I am going to start by replacing that. The only other thing I can think of is the thick coating where the base of the cartridge is sitting is not allowing the extractor to get a good grip on the rim of the casing but still allows the gun to shoot. Worse case scenario is the extractor went bad somehow. I hope that is not the case seeing as how they seem hard to come by from what I have seen. What do you guys think? Bad spring? Bad extractor? Any advice you can give me would be appreciated.