Sorry to hear about your problem. Does the barrel fit the slide well - not too tight or loose? Does the slide hand cycle okay with the KKM barrel installed? Shoot the pistol using the factory 40 barrel and see if the pistol is working okay otherwise.

You are probably going to have to call and possibly send it back to KKM.

I have had perfect reliability out of my KKM 40-9 conversion barrel. I'm sorry you have had a problem. Sounds like you are trying all the right things.