Thinking about buying a used P239, in .40 S&W.

Would I have much trouble and expensive getting a 9mm upper that would work on it?

Thanks!

No need to buy the slide, buy an OEM 9mm barrel and recoil spring and you should be good to go.

Several members have done this with the 239 model.

I have a "semi-fit" 9mm barrel from Bar-Sto that a local smith fit for me. I only have about 100 rounds through it but it worked fine w/ .40 mags and recoil spring.

Personally I think you need a new slide, barrel, recoil spring and magazines and the magazines will be loose in the grip...

Can't quite figure out why you want to go this route when there are a whole lot more 9mm P239s out there... a couple here in our classifies....

Whats your intend end use for this conversion?

If its for range use only then get a factory bbl and spring and go for it. If the end use is for anything serious then forget about wasting your money on a conversion.

Not being able to use a 239/9mm mag in the 239/40-357 frame is a no go for me. Its just not a conversion that i would ever rely on.

Barrel and recoil spring. Hell, some people don't even worry about the recoil spring.

Mags will work fine.

People have literally been doing it for decades at this point. It works. I'm surprised at the negative remarks above.

quote:

Originally posted by chongosuerte:
Barrel and recoil spring. Hell, some people don't even worry about the recoil spring.

Mags will work fine.

People have literally been doing it for decades at this point. It works. I'm surprised at the negative remarks above.

Your a cop and a supervisor right?

So you would use, recommend and support a 239 being converted in this manner for yours and your departments duty guns is what your saying?

I haven't changed anything but the barrel and it's worked fine for over 2000 rounds. If it was all I had I'd be ok carrying it in a pinch.

quote:

Originally posted by Mustang-PaPa:
Whats your intend end use for this conversion?

If its for range use only then get a factory bbl and spring and go for it. If the end use is for anything serious then forget about wasting your money on a conversion.

Not being able to use a 239/9mm mag in the 239/40-357 frame is a no go for me. Its just not a conversion that i would ever rely on.

I've used 9mm mags in my .40 frame more times than I can count and haven't had a single issue. What problems have you had?

quote:

Originally posted by chongosuerte:
Barrel and recoil spring. Hell, some people don't even worry about the recoil spring.

A barrel swap works for me.

Someone else limpwristing it will induce failures. Swapping the recoil spring would probably eliminate the problems, as the slide wasn't fully going back.

quote:

Originally posted by Mustang-PaPa:

quote:

Originally posted by chongosuerte:
Barrel and recoil spring. Hell, some people don't even worry about the recoil spring.

Mags will work fine.

People have literally been doing it for decades at this point. It works. I'm surprised at the negative remarks above.

Your a cop and a supervisor right?

So you would use, recommend and support a 239 being converted in this manner for yours and your departments duty guns is what your saying?

Apples and oranges.

I have converted a P239 to 9mm from .40 with a factory 9mm barrel, spring, and 9mm mags. The sky did not turn dark, and I was not struck with lightening. It functioned properly through thousands of rounds of 9mm, and tens of thousands of rounds of .40. Many others have done the same. It's been a known availability for probably as long as the .40 239 has existed. I don't remember now if Sig specifically acknowledged it, but I think I recall they did...I'm sure someone around here will remember for sure.

When I carried it, I did carry it as a .40. I converted to 9mm to plink and because I could.

I choose not to carry it these days as my CCW because I prefer a Glock 19 or a SIG P365.

I would not have a problem with anyone doing the same, and carrying it after they have put enough rounds through it to have faith in it.

quote:

Originally posted by chongosuerte:

quote:

Originally posted by Mustang-PaPa:

quote:

Originally posted by chongosuerte:
Barrel and recoil spring. Hell, some people don't even worry about the recoil spring.

Mags will work fine.

People have literally been doing it for decades at this point. It works. I'm surprised at the negative remarks above.

Your a cop and a supervisor right?

So you would use, recommend and support a 239 being converted in this manner for yours and your departments duty guns is what your saying?

Apples and oranges.

I have converted a P239 to 9mm from .40 with a factory 9mm barrel, spring, and 9mm mags. The sky did not turn dark, and I was not struck with lightening. It functioned properly through thousands of rounds of 9mm, and tens of thousands of rounds of .40. Many others have done the same. It's been a known availability for probably as long as the .40 239 has existed. I don't remember now if Sig specifically acknowledged it, but I think I recall they did...I'm sure someone around here will remember for sure.

When I carried it, I did carry it as a .40. I converted to 9mm to plink and because I could.

I choose not to carry it these days as my CCW because I prefer a Glock 19 or a SIG P365.

I would not have a problem with anyone doing the same, and carrying it after they have put enough rounds through it to have faith in it.

Well as i recall sigs official stance on doing it was not to do it at all.

Yes these conversions have been done for quite some time with both good and bad results.
Please reread my original post as i am not being negative or misleading in my statements.
Thing is we have a new member asking and many others read it and take it as gospel that its a clean accepted conversion which it isn't.

Again for range use yes go for it and have fun but for anything serious i feel that recommending it or atleast not explaining the risks involved is misleading to new members or the many others that may read these threads.

It's about as close to a clean accepted conversion as one can get.

And the 9mm mags work fine.

Were he asking about turning a 9mm into a .40, it would be different and myself and everyone else would advise against it with no hesitation.

Turning a .40 into a 9mm effectively has no "risks", short of possibly not being supported by the factory for damage. I've not even read of anyone who changed the barrel with a factory 9mm and spring and had issues with reliability, but I wouldn't rule it out.

So OP: If you do the barrel/spring swap be aware that you could theoretically and potentially have reliability issues since the gun wasn't made for it; and that SIG may not warranty any damage caused by shooting it with a different caliber than manufactured (if the gun is still under warranty).

But it will work.

And don't take my word for it:
https://sigforum.com/eve/forums...0601935/m/5790070134
https://sigforum.com/eve/forums...0601935/m/5080092534
https://sigforum.com/eve/forums...0601935/m/8920022634
https://sigforum.com/eve/forums...0601935/m/2680002924
https://sigforum.com/eve/forums...0601935/m/9390078854
https://sigforum.com/eve/forums...0601935/m/9350067724
https://sigforum.com/eve/forums...0601935/m/5670098624

This is copied from one of your linked threads and is by GaryBF which better describes the point i was trying to make to the op about intended use;

Unofficially you can install a factory 9mm barrel in your P239-40. I first did it as an intellectual exercise following a question posted here. I measured both 40 amd 9mm barrels and found them the same except for the barrel hood. I tried the swap using live ammunition and found it did not explode in my hand and the experience was quite satisfactory. I wrote here about my conversion and others have done the same. It works. But do not expect SIG to condone the conversion because it is not perfect. I only use it at the shooting range. You don't even need 9mm magazines and, in fact, I don't suggest using them because they are a loose fit. 40 mags work and 357 mags may work even better. So carry on as you wish.



Again these threads go from good advice to 100% a ok over time. I am just trying to help the op and all the many others that will read this know of the possible risks involved for anything other then range or fun use.

Well dang it!.. now y'all have me wanting to try it... I have both a P239 40/357 and a 9mm.... so the conversion should be simple...

I presumed the slide was also different on the 40/357 to accommodate the larger diameter of the 40 cal barrel. Seems I was wrong....

And so I now have a question.... not to steal the thread...

but I have two P239s:

First is a 9mm in SA/DA

Second is a 357 in DAK..

I'broken both down to a field strip and weighed all the parts.. the slide on the 357 one is 51 grams heavier than the 9mm.... the frame of the 357 DAK is actually 12 grams lighter than the 9mm.. the only difference I can find between the two slides is the 357/40 one says on the side "stainless" the 9mm doesn't.

Question: Can I 'safely' put the 9mm slide on the 357 DAK frame with the 357 barrel and spring and rod and shoot it?

quote:

Originally posted by Blume9mm:
Well dang it!.. now y'all have me wanting to try it... I have both a P239 40/357 and a 9mm.... so the conversion should be simple...

I presumed the slide was also different on the 40/357 to accommodate the larger diameter of the 40 cal barrel. Seems I was wrong....

And so I now have a question.... not to steal the thread...

but I have two P239s:

First is a 9mm in SA/DA

Second is a 357 in DAK..

I'broken both down to a field strip and weighed all the parts.. the slide on the 357 one is 51 grams heavier than the 9mm.... the frame of the 357 DAK is actually 12 grams lighter than the 9mm.. the only difference I can find between the two slides is the 357/40 one says on the side "stainless" the 9mm doesn't.

Question: Can I 'safely' put the 9mm slide on the 357 DAK frame with the 357 barrel and spring and rod and shoot it?

I don’t think a .357 barrel is going to fit in a 9mm slide because of the difference in the dimensions of the barrel hood. If you do manage to get the .357 barrel in the 9mm slide then I don’t think the breech face on a 9mm slide is large enough to accommodate the larger base of the .357 cartridge. If you do somehow manage to get all of that worked out than I would think the answer would still be no. You may get the gun to go bang but the faster slide is, at the very least, going to beat the gun to death.

The 9mm slide is not as strong as the .40/.357. I would not use the 9mm slide for either.

If you mean can you shoot it as a 9mm on the frame for a .40/.357 by just switching the slide...I never tried it. I don’t know that I would.

quote:

Originally posted by Blume9mm:

I presumed the slide was also different on the 40/357 to accommodate the larger diameter of the 40 cal barrel. Seems I was wrong....

I'broken both down to a field strip and weighed all the parts.. the slide on the 357 one is 51 grams heavier than the 9mm.... the frame of the 357 DAK is actually 12 grams lighter than the 9mm.. the only difference I can find between the two slides is the 357/40 one says on the side "stainless" the 9mm doesn't.

Question: Can I 'safely' put the 9mm slide on the 357 DAK frame with the 357 barrel and spring and rod and shoot it?

No

The 40/357 slide is heavier for the bigger calibers.
All 239's have SS slides.

Magwell on the 40/357 is larger, this is why it's lighter.

And NO, you do NOT want to try and shoot 40/357 from a 9 slide.
Slide velocities would damage your pistol.

Only the 40/357 can be downgraded to a smaller caliber.

Thanks folks, that all makes since... and kind of what I was thinking... that there was a reason the 357/40 slide was heavier.....

The one draw back I've found to 'upgrading' from 9mm to 357 in the p239 is the added weight....

Oh, but you can switch it all out... 357 barrel willl fit in the 9mm slide and at least functions by hand.... I need to get out my calipers but I don't think there is a difference the outer diameter of the barrels....

Edit: I just measured the hole in both slides and the outer diameter of all the barrels.. 9mm, 357 & 40caliber and they are all the same... hole in the slide is about 1mm larger than the barrels on both. So, they are all interchange... almost seems like Sig made a mistake with this since according to you experts you don't want to do this... shoot 357 or 40 using the 9mm slide....

quote:

Originally posted by Blume9mm:

Oh, but you can switch it all out... 357 barrel willl fit in the 9mm slide and at least functions by hand.... I need to get out my calipers but I don't think there is a difference the outer diameter of the barrels....

Edit: I just measured the hole in both slides and the outer diameter of all the barrels.. 9mm, 357 & 40caliber and they are all the same... hole in the slide is about 1mm larger than the barrels on both. So, they are all interchange... almost seems like Sig made a mistake with this since according to you experts you don't want to do this... shoot 357 or 40 using the 9mm slide....

I think you are missing the point - not only do you not want to do it, it is not possible to chamber a 357sig/40S&W round in a 357sig/40S&W barrel attached to a 9mm slide because the slide is not sized to accept the increased diameter of the rim of the 357sig/40S&W case. Yes the barrel will fit in the 9mm slide and appears to function but the slide will not go into battery with a round in the chamber, at least without using force and deforming the case rim with unpredictable and undesirable results.