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Discussion Starter · #1 ·
I noticed that the P320 cal x-kits come with a new slide. Is this necessary, or just to jack up the price? Do all the caliber barrels fit in the same slide (assuming it's the right length) - .45 excepted?
 

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Smaller barrels (e.g. 9mm) will fit into larger slide (e.g. 40SW). Larger barrels wont fit into smaller slides.
 

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I would think .357sig and 40sw would be the only 2 that would be the same, but that's just a guess
 
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Stlmia is right on. I learned that with 9mm and 40. The 40 barrel would not fit in 9mm slide. The 9 barrel shoots jut fine in the 40 slide. I also have the 45 but have not tried the 40 in the 45 slide. I assume it will fit.
 

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The 40 and 357 Sig can interchange with a barrel of the same length as the original. The 9 requires a different spring (and barrel od is different, so use it in a 40/357 at your own discretion), but the 45 is a totally different dimension for the FCU and frame. The slides, from compact to subcompact, and full to compact will work within the 9-40 configuration based on the ones I have.
 

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The 40 and 357 Sig can interchange with a barrel of the same length as the original. The 9 requires a different spring (and barrel od is different, so use it in a 40/357 at your own discretion), but the 45 is a totally different dimension for the FCU and frame. The slides, from compact to subcompact, and full to compact will work within the 9-40 configuration based on the ones I have.
Well, technically, the longer barrels will fit into smaller slides, and will probably work. But the smaller barrels obviously wont hold in a larger slide. For example, for any given caliber, a Full Size barrel will fit into a Compact slide. Of course, it would look ridiculous and use your discretion whether or not you want to shoot it that way. Nevertheless, it is possible to assemble it this way.

Also, I've heard of other forum members mention .45 FCUs as being compatible, but not recommended as one of the internal safeties does not engage.
 

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Discussion Starter · #10 ·
Smaller barrels (e.g. 9mm) will fit into larger slide (e.g. 40SW). Larger barrels wont fit into smaller slides.
The 40 and 357 Sig can interchange with a barrel of the same length as the original. The 9 requires a different spring (and barrel od is different, so use it in a 40/357 at your own discretion), but the 45 is a totally different dimension for the FCU and frame. The slides, from compact to subcompact, and full to compact will work within the 9-40 configuration based on the ones I have.
Ok, this is what I figured. Forgetting about the .45, which is essentially an entirely different gun (slide/mags/grip). So the .40/.357 barrels have the same circumference (which means the .357 is thicker?), but the the 9mm is smaller around. So:

- Do the all have the same dimensions in the chamber (in the squared off area). Meaning, will the all lock into the slide the same way in the ejection port? (I guess we need someone who has all 3).

- The 9mm is smaller, so it should fit in the .40/.357 slide, but will the extra space cause any safety or accuracy issues? (Does the P320 even fully lock up at the muzzle/slide hole, or does it all occur at the base end of the barrel).

Essentially I am trying to see if I can make use of the "modularity", and try out some different rounds, without having to pay for 50% of a gun for each caliber (that seems a little exorbitant considering you don't get another "firearm").

So, if I got a P320 in .40 S&W, and just bought a .357 barrel and a 9mm barrel, and the corresponding springs**, would everything fit and shoot fine?



** Sig seems to list only one universal spring for all the model (except the Sub-C), regardless of caliber: https://www.sigsauer.com/store/sig-sauer-p320-recoil-spring-assembly.html
 

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Generally speaking, across multiple manufacturers/platforms, .40 S&W and .357 SIG use the same slide, recoil spring, and magazines... just the barrel has to be changed.

Generally speaking, although a 9mm barrel which is inherently thinner will fit in a .40/.357 SIG slide, I personally would not be comfortable shooting it... unless it's a conversion barrel clearly designed for that application. Usually other parts have to be swapped out for reliability including recoil spring, extractor, etc... different magazines too of course... POA/POI changes too with such a caliber change using a .40/.357 slide... and as mentioned, it's doubtful the barrel fits perfectly.

For me personally, I would not want to mess around and would just pick up the caliber x-change kit for $300-$325 or so when it's listed on Gunbroker or when some retailer has it on sale. Just because it seems to work doesn't mean it's safe in the long run and I would never want to use that config for EDC or home defense... that's just me.

.
 
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Hmmmmmm....

This suggests that the 357sig and 40 Cal-X kits... could be purchased, and a barrel acquired elsewhere, to get the same end result as a 9mm Cal-X kit.

I need to do some shopping...
Technically correct. But again, use your own discretion. Based on what I've seen here on the forum thus far, this is a debatable topic. Some say that the 9mm barrel in the 40SW/357SIG slide runs, and shoots fine. Others who have tried it say that it causes increased wear, and report decreased accuracy with this configuration. I've also seen someone mentioned problems related to firing pin alignment.

Personally, I would not run it this way.
 

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So the .40/.357 barrels have the same circumference (which means the .357 is thicker?), but the the 9mm is smaller around. So:

- Do the all have the same dimensions in the chamber (in the squared off area). Meaning, will the all lock into the slide the same way in the ejection port? (I guess we need someone who has all 3).

- The 9mm is smaller, so it should fit in the .40/.357 slide, but will the extra space cause any safety or accuracy issues? (Does the P320 even fully lock up at the muzzle/slide hole, or does it all occur at the base end of the barrel).

So, if I got a P320 in .40 S&W, and just bought a .357 barrel and a 9mm barrel, and the corresponding springs**, would everything fit and shoot fine?

As others have said, for the 40SW and 357SIG exchange, all you need is a barrel. The 40SW slide and the 357SIG slide is one in the same.

You can play with loose barrels in slide, and yes it will run and shoot fine. But whether or not there are safety and accuracy issues is up for debate.

Personally, I think there would be, and so I wouldn't run it that way.
 

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Discussion Starter · #14 ·
Technically correct. But again, use your own discretion. Based on what I've seen here on the forum thus far, this is a debatable topic. Some say that the 9mm barrel in the 40SW/357SIG slide runs, and shoots fine. Others who have tried it say that it causes increased wear, and report decreased accuracy with this configuration. I've also seen someone mentioned problems related to firing pin alignment.

Personally, I would not run it this way.
I see.


Essentially though, Sig could have made this work by standardizing the external dimensions (both tube and chamber) of the barrels for the three calibers and using one universal slide (in Full, Compact, and Sub-C). This would allow caliber changes to simply be done with a new barrel and mags (though the 9mm might be slightly beefier than necessary, closer to a bull barrel). I wonder if there was an engineering reason they didn't do this, or if it was simply about $$.
 

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I see.


Essentially though, Sig could have made this work by standardizing the external dimensions (both tube and chamber) of the barrels for the three calibers and using one universal slide (in Full, Compact, and Sub-C). This would allow caliber changes to simply be done with a new barrel and mags (though the 9mm might be slightly beefier than necessary, closer to a bull barrel). I wonder if there was an engineering reason they didn't do this, or if it was simply about $$.
You would still need a different recoil spring and extractor probably (especially if they made a thicker/heavier 9mm barrel to fit the slide)... .40/.357 is naturally more powerful and will cycle the slide differently (some 9mm loads would be too weak to properly cycle the slide and eject the shell casing)... and the .40/.357 SIG slide has sights "calibrated", front/rear sizes, for the specific caliber of the pistol. Even when I switch to my .357 SIG barrel in my .40 S&W P320C, the POA/POI is different.

.
 

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For what is worth, I got a P320 Compact in 40sw. Then I added the 357sig and 9mm threaded barrels. The only thing I change out is the barrel. Everything works great. The only issue I've seen is the last round of 9mm can be hard to get into the mag even with a Uplala (spelling) loader. I keep everything well greased too :)

I also got a SC x-change kit in 40sw. I do the same barrel swap to 9mm and don't have any issues.

I do use only good quality factory ammo. I do not buy low cost reloads that are out there. Most of my ammo is Speer Lawman or Speer Gold Dot. Somethings I get Rem or Federal.

Technically there is a PIO change, but it would be fractions of an inch at 7 yards. Even at 25 yards it would be less than an inch. If fractions of an inch are an issue for your shooting, the P320 is most likely not what you should be shoot ... haha.
 

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Discussion Starter · #17 ·
You would still need a different recoil spring and extractor probably (especially if they made a thicker/heavier 9mm barrel to fit the slide)... .40/.357 is naturally more powerful and will cycle the slide differently

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This seems to make sense, but SIG only offers one OEM RSA for all calibers (except .45) and all slide/frame sizes (except sub-c): https://www.sigsauer.com/store/sig-sauer-p320-recoil-spring-assembly.html. It seems that they believe 9mm/.40/.357 all are close enough in force to use the same spring (and even more surprisingly with both the Full size or Compact). Maybe I'm missing something, but I cant see it.

For what is worth, I got a P320 Compact in 40sw. Then I added the 357sig and 9mm threaded barrels. The only thing I change out is the barrel. Everything works great. The only issue I've seen is the last round of 9mm can be hard to get into the mag even with a Uplala (spelling) loader. I keep everything well greased too :)

I also got a SC x-change kit in 40sw. I do the same barrel swap to 9mm and don't have any issues.

I do use only good quality factory ammo. I do not buy low cost reloads that are out there. Most of my ammo is Speer Lawman or Speer Gold Dot. Somethings I get Rem or Federal.

Technically there is a PIO change, but it would be fractions of an inch at 7 yards. Even at 25 yards it would be less than an inch. If fractions of an inch are an issue for your shooting, the P320 is most likely not what you should be shoot ... haha.
Could we trouble you for some pictures? :huh:
 

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This seems to make sense, but SIG only offers one OEM RSA for all calibers (except .45) and all slide/frame sizes (except sub-c): https://www.sigsauer.com/store/sig-sauer-p320-recoil-spring-assembly.html. It seems that they believe 9mm/.40/.357 all are close enough in force to use the same spring (and even more surprisingly with both the Full size or Compact). Maybe I'm missing something, but I cant see it.
Just because it isn't listed online doesn't mean they don't sell it. I'd be confident in saying that to order most smaller parts, you have to call SIG CS.

I only have the P320 in 9mm (full size and compact), so I can't speak for the particular P320 RSA. However, I do have the P250 in both 9mm and 40SW, and the RSA is noticeably different between the two. I would expect that the same is true for the P320. Also, if I'm not mistaken, only one RSA is listed online for the P250 (even though there are obviously others in existence).

Also, when I install the 9mm barrel in the 40SW slide, I do notice a more loose fit overall. And from my perspective, the barrel and slide are noticeably (visually) mismatched when looking at the slide's breach face.
 

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In my compact slide the 40,357sig and 9mm all the same amount of wiggle when against the breech face and when forward in the slide. To me it seems fine as these are not match grade fitted components. That is just my 2-cents.
 
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