So I put 150 rounds of ball ammo and 25 rounds of Speer Gold Dot +P JHP though my Kahr when I bought it new for a shakedown cruise. No failures, shot flawlessly.

Have practiced with ball several times since, without issues.  Fast forward to last month, when I let my brother shoot the pistol along with my 1911s to see what pistol he would like to buy to carry.

Unfortunately, at the time all I could find was some factory loaded flatnose FMJ, box 50 rounds. When we fire the CM40 with this ammo, it jammed about every 3rd round, and you could see the rounds try to hang up while feeding, even when they did chamber. All of the failures were failure to feed.

Then, I figured, I'll try my personal defense round I had with me, but all of those (Speer Gold Dots) also misfed as well, even though they had worked in the past. So I went and parked the Kahr, and shot the 1911s and M&P9 which all worked without issue.

When I took apart the CM40 to clean it, I notice a small burr on the left side of the feed ramp  had not noticed before, rough to the touch, and figured maybe the flatnose ammo had caused it when it misfed.
I call Kahr, and they open an RMA and send me a label to print out, and mail it in, at no cost to me. Well when they called me they said they polished the feed ramp, and got rid of the burr, but they said it shot fine without issue, before and after the feed ramp work with both round-nosed FMJ ball and JHP ammo. They said they used Winchester silvertip JHP ammo for the JHP test.
They said they did not think the burr was causing a problem.

So they are sending it back. My consternation arises from the fact that they did not find anything definitively wrong with the pistol. Should I switch my carry ammo to Winchester Silvertips, and test 100 rounds with that to re-establish reliability for carry?

Or  should I sell it and buy something that feeds anything? I do not understand why it worked reliably with Speer Gold Dots before, but didn't when I last shot it. I don't like guns that are picky about ammo.

What would you guys do. Ideas?

Odd that it worked with the gold dots prior to, but not after.  I would say it was worth a shot trying the silver tips, if you could find them.  I run Rem Gold Sabre or Hornady Critical Defense in my CW9, ran 50 rounds of each randomly loaded in mags of my plinking ammo before I settled on those two carry rounds.

Yeah, I have two boxes of Winchester JHP +P on hand, I just hate to get into the scenario where I have to spend a small fortune on ammo to prove that a pistol is not reliable, only to sell it for something that is.

Been there before....So it is often with pocket pistols it seems.

Kahr PM9 Striker Spacer is damaged and I can't get the slide plate off! It's pushed into the rear of the slide! The small hole in the slide plate! I detail strip about every 6 months to clean, so it's not my first pony show. Anyone else have this issue? I don't want to send it back to Kahr! They charge an arm and a leg for repairs!

I have a CM40 that runs great, but one thing I have noticed is that unless I'm gripping it pretty hard it can jam up on me, like a nose dive.  I've had a number of Kahrs and I like the CM40 a lot, so I'm passing on the suggestion to grip it very tightly when you go to shoot it, it seems more prone to misfeed if your grip isn't very firm compared to other makes.    I'm not saying you're limp wristing, but what I'm saying is that for me, I can shoot say a Glock .40 just fine using a firm grip, but if I don't grip the Kahr really tight it has a tendency to malfunction with anything less than a strong grip.

My cw40 would jam if I didn't death grip it, when I remembered to death grip it it would feed 100% later on in the range session between loading mags, sometimes I would forget to death grip, it would jam until I death gripped it again, I got rid of it because I didn't want to grip train everytime I fired that gun.