My PM9 is about 10 years old and I have carried it every day since purchase.  It has been flawless and I have been very happy.

I was cleaning it the other day and i found a spot of rust inside the bore about 1/8" round about 1/2" in from the muzzle.  The rust does not come off with bore brush scrubbing.

I called Kahr and was told that rust is not covered under warranty and to buy a new barrel.

I am frustrated and disappointed in their response.  Isn't the barrel stainless?  What is the point of buying a gun with stainless mentioned several times in the marketing information if it is going to rust anyway?

So do I buy a new barrel at $150?
Shoot it and not worry about the rust?
Use opportunity to buy a new carry gun?

Thoughts?

Lead remover patch from Brownell forced through the bore.
Anything left should be below bored surface.
Then if it shoots alright it is fine.
If it was mine I would probably go ahead and shoot after scrubbing repeatedly with bore brush.

Only the slide, frame, and some small parts are really stainless steel.
Most small parts and the barrel are hard chrome plated carbon steel.

I recommend buying a jar of JB Bore Paste and some Kroil from Brownell's or a gun shop.

Soak the bore in Kroil for at least 24 hours to soften and loosen the rust.
Then use the JB Bore Paste and Kroil on patches to throughly scrub out the bore per the instructions.

This will remove the rust, but there will be at least some pitting.
This is no big deal, since a lot of guns are badly pitted and still shoot extremely well.
In a small defense handgun the pitting will have zero effect on anything and you can shoot the gun forever with no problems.

If you don't want to go to the trouble of ordering JB and Kroil, just buy a new bore brush, and soak the bore with a bore solvent like Hoppe's #9 for 24 hours, then liberally brush out the bore.
This too should remove the rust.
Note that you should use a new correct caliber bore brush.  An over-caliber bore brush just folds over the bristles and doesn't work any better.

Yet another trick is to buy some COPPER Chore Boy pot scrubber pads.
Pull off a strand or two and wrap around a bore brush.
This will also scrub off the rust.
NOTE: Use GENUINE Chore Boy that says 100% Copper on the label.  Other brands are actually stainless steel with a copper plate.
These can destroy a barrel.

If it absolutely just bugs you, then consider having Kahr fit a new barrel, or trade it in on a new gun.

Personally, If I had a reliable Kahr I could live very well with a pit or two.

Also keep in mind that stainless is not rust less. Only less prone to rust.

Big difference

Yup, pocket carried guns are very susceptible to this. They really should have a very lightly oiled mop run through the bore occasionally to prevent this kind of thing, my guess is it will still shoot just fine. I've bought a Beretta 21a that had the end of the barrel completely eaten out by rust, it was cheap as the barrel was ruined, from pocket carry.

shoot it and check groups.  odds are it is fine, but will foul more in the "rusted" area.