First of all: Happy 2018 and thank you for reading and responding to my post.
Called Sig today to inquire as to when the P239 9mm barrels will be back in stock. The response I got from the customer service rep is “soon”!

Then we discussed swapping the 9mm barrel with my current .40. With the utmost confidence in the world, I was assured this is impossible and was told the only way is with an action kit (slide/barrel/recoil spring) which Sig does not make for the P239. Is the customer rep blowing smoke up my barrel? If so, can someone recommend another source for a barrel. I understand I will have to buy the 9mm mags as the .40 & .357 are not interchangeable with the 9mm.
For those of you asking why I would go from .40 to a 9; because of my source of 9mm brass and reloads. As a carry, the P239 will be back with the .40 barrel.

Happy New Year

Swap Sig barrel. Shoot gun.

Get a 9mm spring if you want. Cheap.

9mm shoots fine in the .40 mags. .357 is where you run into issues with mags.

Top Gun Supply has threaded barrels in stock for $200. No regular ones tho.

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.

Thnks for the input and quick response.

Per GaryBF, there is no problem using the SIg OEM 9mm barrel in the P239 .40. About a dozen others on the forum, including me, have done it with no problems regarding functionality or safety. There are a LOT of older threads that discussed this.

My "converted" 9mm also uses BOTH Sig 9mm AND .40 mags with no functioning issues.

I also use the defunct Sig "Plus 1" mag kits for both calibers. Sig marketed them for use in the .40 mags ONLY. Somebody forgot to tell the 9mm mags, since they are just fine with the .40 kits.

Count me in among those who have experienced excellent operation just swapping barrels. My 9 mm barrel is a Barsto, but gets good results. 357 Sig mags work perfectly.

Like many other Forum members here, I have been running a factory 9MM barrel in my 357SIG 239s for MANY years.

Since I do prefer 357SIG to 9MM, I probably have put only a thousand or so rounds of 9MM downrange with the P239



My factory barrel happens to be threaded so most of the ammunition I have shot was through the suppressor.

I never changed the spring and I never bought 9MM magazines, the ones that came with my P239s work just fine

I swapped out a 357Sig with an OEM 9mm barrel.
Worked fine for me.

Limp wristing the pistol will require a 9mm recoil spring.

Thanks for the input! I was aware this issue had been discussed many times and I appreciate your confidence and support. I wanted to highlight what the Sig Customer Service Rep said and told me it was impossible! I know they cant endorse people from modifying their handgun, but they make a pretty penny doing what we all do at home!

Happy 2018!

May I add after reading all of the favorBle posts; NO THE P239 IS NOT DEAD!

I bought my P239 as a .357 Sig, bought a .40 S&W barrel and converted it successfully (with the barrel and magazines), then purchased a 9mm factory barrel and recoil spring. As a 9mm, my P239 has functioned 100% with .40 S&W and .357 Sig magazines and is probably more accurate in this configuration than the others. Couldn't be happier!

Many of us on this site have used Sig barrels for this P239. Mine in 40 s&w with .357 Sig & 9mm barrels.

How are the sights when shooting 9mm from an original .40?

The difference in POI is almost negligible unless you go beyond 25 yards. You could find a compromise sight set if you really felt it necessary.