I have a Kahr P9. I had failure to battery problems right out of the box. The folks at Kahr, though very nice people, were of no use solving my problem. I finally figured it out as excessive extractor tension. The cartridge was not sliding easily under the extractor which caused excessive friction as the slide moved foward and prevented the slide to go fully into battery.
I lowered the extractor tension from 64 Oz.!!! Yes, 64 Oz., to 32 Oz. and my P9 has performed flawlessly ever since.
A shill on the Kahr talk forum suggested I had no right to the Kahr specification for extractor tension. The service person at Kahr said that "some info they do not want us giving out". Makes you feel good about their product, huh?
I know some folks who had zero problems with their Kahr pistols. Personally, I will not take a chance with them again. Once burned, twice shy. Good luck.