In years passed, I've had a few Kahrs. Two E9s, 2 PM9s, a P9, and a PT45.
One of my PM9s had to go back for their recall/upgrade work, I forget the gist of it all. The PT45 had to go back twice. It was failing to detonate a couple brands of ammo consistently. The 2nd visit they figured out the chamber was cut too deeply.