HankB - was yours a NEW production with the screw, or an old, upgraded one? Mine was the latter, and I had the same "repeat trigger pull to fire" issue. I could pull the trigger half a dozen times, and it would click each time, then finally fire.
UTVols - If you like the MK9, then you have no quality worries. I've had 3 all steel Kahrs, and never had a single problem between any of them. My wife's MK9 is her favorite pistol ever... so much so, that she won't let me buy her another one just for the nightstand!
The only issues with all steel Kahrs are the weight. But with a good belt and the right holster, it's not a problem. If I could do it over, knowing what I do now about how much difference the above makes, 'd prefer a Kahr K40 over my P40, just because there's still a TINY hint of doubt that someday, the P40 might cause me a problem. I have only ever heard of one person that had a problem with the "K" kahrs.