9mm upper fits nicely on PM40 frame

[jimsea]

I researched this topic and found only one hit. Feel free to let me know if it has been discussed further.

I was messing around tonight with my PM40 and the complete upper to my CM9. The only difference between the two frames was the mag well on the 9mm frame was just slightly narrower length-wise. Structurally they appear identical.

This means the complete 9mm upper slid perfectly onto the PM40 frame and cycled 9mm rounds smoothly. The 9mm rounds were loaded into the .40 mag and 9mm mags. Because the .40 mags were just slightly longer they were slightly more snug fore and aft in the mag well.

The complete .40 upper slid nicely onto the CM frame, however since the mag well was ever so slightly narrower length wise, the .40 mag would not go in. Tomorrow I'll check to see if .40 ammo will fit the 9mm mag. I forgot to check it. Whether either setup with slightly different dimensions on the mag well will feed and shoot reliably.......don't know yet.

Interesting stuff to know. However, for what you would pay for a complete upper of either caliber, you could buy a new CM pistol in that caliber.

[krazman]

Interesting stuff to know. However, for what you would pay for a complete upper of either caliber, you could buy a new CM pistol in that caliber.

Sorry, not being rude. But...what's the point here. I don't get it.
kraz

[jimsea]

Sorry, not being rude. But...what's the point here. I don't get it.
kraz

My rudeness detector didn't register. lol

There are 9mm drop in barrels designed for .40 cal handguns. There are a lot of people who enjoy shooting both calibers without having to buy two complete pistols.

No such drop in barrel exists for the Kahr 40. I thought the observations in the OP were interesting. It appears you can shoot 9mm out of the .40 but it will require a little more than just the barrel.

I find discussion of compatibility of various components between different handgun models interesting. Some may not but that's OK too.

[krazman]

Thanks for the explanation!

Initially, I thought it sounded like a "I just bolted a Yugo wheel on my Silverado, and it fit" thread.

I have seen kits, especially for Glock, to go from 9mm (or larger) to. 22LR. These always involved a slight cash savings. Doesn't seem to be any savings with the Kahr.

kraz

[CJB]

There are places that make a second handgun very hard to get. Having dual caliber on one pistol is a good thing in that situation.

[jimsea]

I'm still researching to make sure all the various components/springs of the 9 and 40 slides are identical.

For guys with a PM or CM40 who want to shoot 9mm, it is looking like a 9mm slide and barrel is all you need. If the internal slide parts turn out to be identical, you can scavenge the internal parts of the .40 slide and put them in the nine when you detail strip the slide. Six 9mm rounds load into the .40 mag easily.

It will be a few days before I can test fire some rounds.

[wyntrout]

The mags are really close. I experimented with switching my 7-round 9mm mags to 6-round .40 S&W. The followers MAY be the same, not sure. The tubes are a tiny bit tighter on the 9mm, and the bases and magazine springs are interchangeable.

I tried stretching the top of the 9mm mags a bit ... prying them apart. They loaded okay, but weren't reliable, so I stopped trying that and ordered more of the .40 mags.
Reliable function is paramount for defensive stuff, especially mags and pistols for CCW or home defense!

A "little" play fore and aft in the barrel fit could cause pounding and failure of the polymer frame. I just don't see a reason to try this. These pistols... the "C" models can be found for about $350 or less. If you destroy a frame... or worse, you'll have to buy a new one... maybe a whole new pistol, by the time you add up parts costs.

My ported P9/CW9 barrel is so designated and because it seemed to fit in my K9 didn't make me want to fire it that way. There are differences that could be critical as far as froward and aft movement and locking the barrel to the slide to fire. That barrel must mate with the barrel for the action to work properly. It may or may not in your case, but it's not DESIGNED to fit or work as you're considering!

Wynn:)

[jimsea]

I am using the .40 mags with 9mm rounds so there is no fitment issue inside the .40 frame/magwell.

The 9mm slide and barrel are already mated so no issue there either.

The only issue that i see possibly is the polymer frame doing a break in to an additional slide. While both slides are machined the same and fit perfectly..... ..as you and i know, no two things are really ever identical, so this could cause extra wear on the polymer.

Regardless, i am going to shoot to see how well she does. I have both the 9 and 40 polymer frames and will mate them up accordingly after my "experiment."

Hey.... You can't try this stuff with the guns at the LGS. They would give you a fun y look and throw you out. :eek:

[wyntrout]

I have some cheap Kevlar-reinforced gloves that I wear for "testing"... those AND eye protection... real ballistic-type shooting glasses. Be careful! Video, if possible.:D

Maybe a towel around your neck and a cap with the brim pulled down as far as possible!

Wynn:)

[wyntrout]

I had a problem with some certain cases in factory reloads... 9mm... had case ruptures... blew out extractor on PM9, I guess. I didn't know what cuased that.

I got a P9 and was using that ammo... had about 830 rounds over a decade with no NOTICED problems, but had a case rupture and blew out the side plate... did later find the extractor and figured out the case this time.

To finish off the suspect round, I picked through the remaining 150 or so and found just 5 or so left from a case of 1,000 rounds. I used my all-steel K9 to fire the last 5 rounds on another trip to the range. For some reason, I had the camera recording bullet impacts on the target and didn't think to point it at the pistol as I fired the suspect rounds. On the second of the 5, I felt splatter on my face and found the extractor was gone! I wish that I had had the camera going on the pistol! I tore the bullets out of the remaining three rounds and fired the primers, then burned the powder... posted the video, too! Cannon fuse is like a rocket when lit and there no appreciable weight to hold it down, which was the case with the small plastic container (cover) that I used!

I'll post that link here in a sec. There's a video link to the rupture thread containing powder burn link on page two.

http://kahrtalk.com/showthread.php?t=15235&highlight=powder+burn

Wynn:D

[jeepster09]

Just look at the Glocks, not uncommon to shoot several calibers out of same gun. I shoot both 40 and 10's out of my G20. I have 2nd barell but some do it with same barell.

[jimsea]

I'll be hand cycling some rounds to check for fitment and reliability.



This morning I hand cycled a few rounds. Didn't get a warm and fuzzy while doing it. While it was an interesting observation having both platforms in front of me, I have waved off shooting it in this configuration.

[antimatter]

I had this same thought, now that I've just ordered a CM9.

I've always sort of wished I had been more educated when I bought my Glock 26... A Glock 27 with a 9mm barrel for practice and plinking and the .40 barrel to carry would have been nice.

[scosgt]

Just want to note for fun:

The frames on the Star Firestar 9mm and .40 are identical. I took a .40 upper and slipped it onto my 9mm frame and got jam after jam, all PSL. Found out the slide stop has to be shaved to allow the .40 rounds to pass by.
Did that and the gun works absolutely perfectly.
My friend who used to work for Star and bought out the parts when they folded advises me that they were indeed the same frame, same ejector. Only the slide/barrel/recoil spring are different. In fact, 9mm mags work perfectly firing .40 in that gun.

So it can be done, just depends on the gun. Kahr is not about to tell you to do it, but if it works it works. If the upper goes on and it cycles smoothly it is not going to blow up. Just make sure to use the recoil spring that goes with the upper, because the .40 spring is likely stronger. And the proper slide stop, of course.