I looked at your pictures and I don't understand the concern. Are you questioning the gap in the slide on top of the barrel? I see the marks that you are talking about and I just took out my CW9 that I have had for a few years and shot 1000'ss of round through. I see some similar marks on my barrel. It is not a cause for concern for me at all i carry this weapon everyday. It looks normal to me.
If you don't like the scratches you are pointing out I suggest you sell it and get a different gun is my opinion. Because if this make you disatisfied with a Kahr you will not ever be satisfied with a Kahr.
I personally put more emphasis on the way the gun shoots how it feels and if I can conceal it properly. Maybe you cant hit anything with it and you think this may be the cause? I own Kahrs and I would gladly take your CW40 and give you an handful of rocks, then bet you 500 bucks I can do more damage to some ballistic gel then you can and I would gladly use your gun you cant trust and give you big rocks.
There is a site dedicated to Kahrtalk dot com that has some very very knowelegable Kahr folks who could either put your mind at ease or who might buy the gun from you. Check them out. They know Kahrs. I would not worry about what you are seeing but I worry about different stuff then some folks. Good luck with your concerns. Kahrs are fine weapons and the CW is a great platform.