Wondering if the P239 mags in 40S&W is the same as 357Sig, are they interchangeable?
My P239SAS is 40S&W and can only find 357Sig mags...
thank you in advance for any info...

I believe the .357 SIG mags don’t feed .40 well but the .40 will feed .357SIG or vice versa. I can’t remember which.

I have shot .357 Sig out of my .40 mags but I never tried to shoot .40s out of my .357 Sig mags.

quote:

Originally posted by mtbiker59:
Wondering if the P239 mags in 40S&W is the same as 357Sig, are they interchangeable?
My P239SAS is 40S&W and can only find 357Sig mags...
thank you in advance for any info...

Scroll down towards the bottom for some pictures and description of the two mags (they are not the same).

https://sigforum.com/eve/forums...840073064#1840073064

In stock p239 .40 mags

https://www.midwestgunworks.co...wi/prod/MAG-239-40-7

quote:

Originally posted by Tusk:

quote:

Originally posted by mtbiker59:
Wondering if the P239 mags in 40S&W is the same as 357Sig, are they interchangeable?
My P239SAS is 40S&W and can only find 357Sig mags...
thank you in advance for any info...

Scroll down towards the bottom for some pictures and description of the two mags (they are not the same).

https://sigforum.com/eve/forums...840073064#1840073064

In stock p239 .40 mags

https://www.midwestgunworks.co...wi/prod/MAG-239-40-7

Thank you Tusk,
I did see the pictures, yes they are different so I have to get 40S&W specific and the web store only has one in stock...

quote:

Originally posted by mtbiker59:
Wondering if the P239 mags in 40S&W is the same as 357Sig, are they interchangeable?
My P239SAS is 40S&W and can only find 357Sig mags...
thank you in advance for any info...

There are usually a few .40 Sig magazines on ebay if You happen to use it but some sellers are way over priced on them so look around at all the listings. Never had any problems using .357 in the .40 mags but at least in my mags, the .40 doesn't fit well in the 357 mags.

Seems I learn something every time I come to the Sig forum...

I thought there was no difference and I know that 40 cal mags can be used for 357s with the P239 with no problem... but never thought about the other direction. I just bought a couple more 40 cal mags and decided to compare the two and there is a definite difference...


If you absolutely need a mag or even two let me know.

40 cal mags for sale in the classified here:

https://sigforum.com/eve/forums...0601935/m/6940046664

One of the beauties of the 357SIG magazines is that they have no problems properly feeding 9MM Parabellum ammunition through them while keeping the projectiles centered on the feed ramp

To be fair, the 40 S&W mags also work with a very little chance of problems even though the cartridge is sitting somewhat differently

I was tempted to buy a box of 40cal ammo to run through my P239 but just have not had the time... maybe next time I'm at a gun show I'll pick some up... Like I said and others have too... no problem shooting 357sig with 40cal mags....

but you can see their is a difference in the two pictured above how the mags are indented.

I keep meaning to switch out the barrel and possibly recoil spring and see how 9mm does with a 357/40 cal slide.

quote:

I keep meaning to switch out the barrel and possibly recoil spring and see how 9mm does with a 357/40 cal slide.

A spring change is not necessary. So far I have well over 1000 rounds of 9MM Parabellum ammunition through my 357SIG P239 with only a barrel change. I am using a Factoy OEM threaded barrel. Reliabiity has been 100% so far



It has not mattered if I was using the suppressor or not

Most of the 9MM Parabellum ammunition used was either the IMI 115 JHP or the Winchester Ranger 147 Subsonic

ALL rounds were fired from 357SIG magazines

Remember the P239 does not need a conversion barrel. The exterior dimensions of the factory 9mm, 357SIG and 40S&W barrels are all the same

Should you choose to use a similar setup for defensive purposes, please run several hundred rounds of your chosen defense ammunition through the firearm to confirm total reliability

Colt sea,

I think your wrote that last part wrong... from what you have experienced... one would need the 9mm barrel to convert a 357/40 P239 to 9mm but nothing else... recoil spring and slide could stay the same....

You are right in that the exterior diameter of all three barrels are the same and so the slide will work on any... but I've been told to not used a 9mm slide with a 357/40 round... the 9mm slide is slightly lighter...(1.8 oz / 52gms) also slightly thinner and not as tall.

quote:

Originally posted by Blume9mm:
Colt sea,

I think your wrote that last part wrong... from what you have experienced... one would need the 9mm barrel to convert a 357/40 P239 to 9mm but nothing else... recoil spring and slide could stay the same....

You are right in that the exterior diameter of all three barrels are the same and so the slide will work on any... but I've been told to not used a 9mm slide with a 357/40 round... the 9mm slide is slightly lighter...(1.8 oz / 52gms) also slightly thinner and not as tall.

No, I never said the slide dimensions were the same, a 9MM slide should not be used to fire 357/40, I said the exterior barrel dimensions were the same and that is why you can use a OEM barrel instead of a conversion barrel

This message has been edited. Last edited by: colt_saa,