Can anyone tell me if a pm40 uses the same frame as the cm9?  In other words would a cm9 complete upper half work on a pm 40 complete lower frame?  And of course 9mm mags would have to fit the 40 frame.  Thanks

I know a PM40 slide is wider than a PM9 slide, so I would think this won't work but I can't say that for certain

Verified: Kahr CM9 slide/barrel/recoil spring assembly DOES, in fact, FIT onto Kahr PM40 lower frame. Kahr factory refused comment on this issue. Some caveats below:

1) CM9 slide and PM40 slide is same width/height but not length (see below). Fit was spot on barring length difference of CM9 slide assembly.

2) CM9 slide fits exactly over PM40 frame and is flush fit on the rear with slide function unhindered, but leaves about 3/8" of the lower PM40 frame exposed in the front as PM40 slide/barrel is fact longer than the CM9 slide/barrel.

3) PM40 slide retaining pin works with CM9 slide/barrel/recoil spring assembly atop PM40 frame. It's guesswork to remove CM9 slide/barrel in place on PM40 frame if you do not commit to memory where PM40 inner retention tang of PM40 slide release is relative to CM9 slide retention pin recess is. CM9 slide release/retaining pin not tried as none in possession.

4) PM40 mags will hold 9mm rounds and cycle accordingly with CM9 slide/barrel/recoil assembly atop PM40 frame. Did not try with Kahr 9mm mags of any variant.

5) Could not get CM9 slide/barrel/recoil spring to lock back open atop PM40 frame, with or without PM40 mag in place. Other posters on other forums seem to have gotten this to work for them. Perhaps they used CM9/PM9 mags.
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6) Hand cycling CM9 slide/barrel/recoil spring assembly atop PM40 frame requires as much effort as PM40 slide/barrel recoil assembly. Not easier as expected.

7) Due to 3/8"+ shorter difference in length, CM9 barrel was not emplaced into PM40 slide to ascertain function.

8) Works, but not aesthetically pleasing to the eye with shorter length difference of CM9 slide/barrel/recoil spring assembly atop PM40 frame.

9) For those wondering why this is a discussion topic, it is because the expensive PM40 (relative to any other sub-compact 40S&W) has one of the WORST recoils for a sub-compact 40S&W. While conversion barrels exist for Sig, Glock, Springfield; apparently, no one thinks it's worth it to do for Kahr compacts. The accuracy is espoused commercially while purposely ignoring that this is NOT an easy gun to shoot; hence the quest for 9mm conversion options for those already out the cash on a purchase based on the accuracy/thin profile characteristics of this firearm.

10) Proof of last point is Kahr's own CEO, Justin Moon, marketing a magna-ported PM40 compared to a stock PM40 as seen on YouTube. He can barely keep his hand on the stock PM40 due to recoil when seen in slow motion on the video. S&W learned from Kahr's mistake and sell their Shield 40S&W in a ported configuration. The Glock 27, albeit a double stack 40S&W, is much more pleasant to shoot.

Thanks CaseFinder!