Bought a K9 back in 1998 -- still have it. When I first fired it, I had 1 out of 3 failures to return to battery;I returned the pistol to Kahr, They polished the ejector a bit and did some other tweaks. After that she behaved well. I took to firing mostly +p and 1240fps 124gr mil loads. A tech at Kahr suggested that I might want to try the K40 recoil spring. This, to improve on return to battery and to take some of the "snap" out of the felt recoil. That works like a charm! As I remember it, the K40 spring has 23 wraps (turns) while the K9 one has 21 wraps. -- Can be ordered from Kahr. I added the crimson trace laser grips --- they're still working fine. Also bought the stainless guide rod etc. Then I bought the ported barrel --- big mistake in my opinion. The ports are slots cut into the top of the protruding barrel end. The problem is that they were slanted, bottom end toward the breech, top toward the muzzle. The result was that many of the rounds fired had metal shaved off by those sharp slot edges as they exited the barrel -- bad. Then came the Kahr T9. Its barrel is basically the extended ported K9 barrel but without the ports! It is basically a drop-in for the K9! A tad of polishing may be required to get a smooth fit. I like the half-inch extended barrel for the improved accuracy and velocity, without the added size & weight of the T9. This is my go-to service 9.