40 S&W to .357 Sig

[Lennyjoe]

I prefer the .357 Sig to the .40 cal and even more so as a Reloader.

 

[herrwalther]

Frame cracking can be dealt with pretty easily... Springs, Buffers, Compensators, even porting a barrel. The locking system is a whole different matter. Then you throw in slide design. Most semi auto locked slides you have a weak point under the ejection port by back by the extractor. So you have to keep an eye on that area along with the barrel to slide locking surfaces.

To a degree, that was my point. I would not want to stick a 357 Sig barrel in a 40 caliber BHP and call it good. On some firearms this is all that is needed. Glock and Sig do well on caliber conversions, not just 40 -> 357 Sig, using only a barrel swap.

 

[fxvr5]

According to CIP, max pressure for 357 SIg is 44,240 PSI. That pressure is another ball park compared to 9mm and 40. I would not want to have that kind of pressure in an old design that was not built for it.

I hate to break the news to you, but the 100+ year old 1911 has been chambered in the 9X23 Winchester, which has a pressure limit of 55,000 psi. And as a reminder, the 1911 was designed around a 45 Auto with a pressure limit of 21,000 psi.

 

[starling]

To a degree, that was my point. I would not want to stick a 357 Sig barrel in a 40 caliber BHP and call it good. On some firearms this is all that is needed. Glock and Sig do well on caliber conversions, not just 40 -> 357 Sig, using only a barrel swap.

We are on the same page. I did a 38 super conversion on a Tokarev. On paper it looked fine but there was a bit more to it than a simple barrel swap as opposed to going 7.62x25 to 9mm para. Start throwing in modern high pressure cartridges with older designs and things can get shakey.

Always easier to do conversions down than it is up. Those are fun as well though. A while back there were a few converting those stronger 40S&W hi-powers to 9mm so they could run hotter loads without wear issues. Not sure who was making the barrels. Hopefully the new FN hi-powers had other more modern cartridges in mind when they developed the new FN High Powers. Kind of looks like it from what I can tell.

 

[trackskippy]

The two primary bullets I plan to shoot through this Sig or any other .358" bore matching bullet are the 125gr GD and cast hp, powder coated, gas checked bullets. I'll find the right alloy for the higher chamber pressure possible. So would others agree that a hot 9mm load is close to a .357 Sig? Please reply, if so, I'll save my money and conduct some experiments with the cast bullet combination I mentioned first, instead.

As was mentioned, you want .355-356 bullets. You also want the profiles more like the 147 grain 9mm bullets as the lesser weight 9mm bullets have a different profile and they dont work as well, if at all in the 357SIG.

According to CIP, max pressure for 357 SIg is 44,240 PSI. That pressure is another ball park compared to 9mm and 40. I would not want to have that kind of pressure in an old design that was not built for it.

Have they raised the max pressure? It always used to be 40000psi (SAAMI), and there was no +P for it.

CIP calls it the .357 SIG, and SAAMI calls it the .357 Sig. Note the capitalization. CIP has a higher MAP than SAAMI.

This has always been something that's caused a lot of confusion. They measure pressure differently, and the CIP always seems to have a higher number, but its not necessarily a higher pressure/power. There is no equality or way to compare them either, other than shooting rounds of the same lot and measuring them.

Ive never understood why they dont settle on one method or at least show both ratings on the boxes or literature/specs so if you only follow one, you know what it is.

 

[herrwalther]

Have they raised the max pressure? It always used to be 40000psi (SAAMI), and there was no +P for it.

This has always been something that's caused a lot of confusion. They measure pressure differently, and the CIP always seems to have a higher number, but its not necessarily a higher pressure/power. There is no equality or way to compare them either, other than shooting rounds of the same lot and measuring them.

You answer your own question. CIP and SAAMI measure slightly differently. CIP has one measure of max pressure for 357 Sig, SAAMI has their own.

I hate to break the news to you, but the 100+ year old 1911 has been chambered in the 9X23 Winchester, which has a pressure limit of 55,000 psi. And as a reminder, the 1911 was designed around a 45 Auto with a pressure limit of 21,000 psi.

Precursors to the 1911 used higher pressure rounds like 38 ACP before the 45ACP. Very little changed mechanically from The M1900 to the 1902 etc to the 1911. Because the precursors were designed with higher pressure rounds JMB had in mind and then worked down in pressure/velocity to the 45ACP the military had in mind, the frames and slide link ups can handle a variety of rounds like 9x23, 460 Rowland, 400 Corbon, and many others.

 

[Gerd33]

I usually stick to .357 sig but I also have .40 barrels for my Sig P series pistols since it's just a simple barrel swap to switch between the two calibers for the P224, P226, P229, and P239 and I like having the option even if not utilized.

 

[trackskippy]

You answer your own question. CIP and SAAMI measure slightly differently. CIP has one measure of max pressure for 357 Sig, SAAMI has their own.

Which were you quoting/citing, that's what was confusing me a bit there? Its been a while since Ive paid close attention to it, and was wondering if the 44K number was something new.

I know some of the boutique ammo makers claim higher velocities with some loadings, but my understanding has always been that they do it within the SAAMI pressure threshold which is still 40K psi.

Edit: Di YA, never mind. I see you were quoting CIP.

It would help if we keep things "apples to apples".

 

[herrwalther]

Which were you quoting/citing, that's what was confusing me a bit there? Its been a while since Ive paid close attention to it, and was wondering if the 44K number was something new.

I quoted CIP max pressure in post 19. SAAMI max pressure is still 40,000 PSI. Even for a venerable caliber like 9mm Luger, CIP and SAAMI differ by almost 1000 PSI at max pressure.

 

[Nuclear]

I don’t think a BHP conversion to 357Sig should make any difference as CorBon produced SAAMI spec 135 grain rounds that were very close to 357Sig velocities.

The threads on such conversions (really just replacing the barrel) over on the handgunsandammunition.com board (Stephan Camp’s old forum) don’t show any issues.

 

[trackskippy]

I usually stick to .357 sig but I also have .40 barrels for my Sig P series pistols since it's just a simple barrel swap to switch between the two calibers for the P224, P226, P229, and P239 and I like having the option even if not utilized.

I thought the same thing when I first got them, but quickly realized, I had a lot of money tied up in something that was just sitting there, and never likely to be used.

I quoted CIP max pressure in post 19. SAAMI max pressure is still 40,000 PSI. Even for a venerable caliber like 9mm Luger, CIP and SAAMI differ by almost 1000 PSI at max pressure.

Thats the problem that needs addressed, especially when we arent speaking the same language.

You always hear that Euro ammo is "hotter" when I think it really isn't when you get right down to it.

 

[herrwalther]

You always hear that Euro ammo is "hotter" when I think it really isn't when you get right down to it.

I know when I did side by side training with NATO countries, their ammo had more variation it terms of recoil impulse depending on where it came from. Some stronger, some weaker, some just different. In theory a 9mm NATO, 124 gr bullet loaded to 36,500 PSI should be the same whether it is made in the US, Turkey, Spain, or North Macedonia. But they aren't. American ammo is much more consistent feel from one shot to the next. In overseas stuff, not so much. So the CIP "standard" is more of a pressure range than SAAMI.

 

[trackskippy]

Ive shot a lot of Euro 9mm over the years. Some of it NATO, some of it supposed SMG rated ammo. That ammo definitely had more zip to it, but the other stuff was all pretty much the same.

I still have some of both that I haven't shot because its corrosive. Ill have to get the chrono out and see what it actually clocks at. I also have some USGI 9mm. I'll run some of that with it. I have a feeling, the non SMG stuff is going to be close.

Since it seems like pretty much most of the rest of the world goes with CIP, we should switch to that. Would just make things a lot more simple. But seeing how hard it is for Americans to understand the metric system, I dont see that happening in our lifetime.

 

[kcofohio]

Both of our 40s, an M&P40 and Shield40, have 357 SIG barrels. I did it for the novelty and versatility.
As for lead, I have a Lee 358-125 mold that I powder coat. Tried them out in the M&P, they shot accurately.

I did buy some stronger recoil springs for the M&P.

 

[BJung]

Both of our 40s, an M&P40 and Shield40, have 357 SIG barrels. I did it for the novelty and versatility.
As for lead, I have a Lee 358-125 mold that I powder coat. Tried them out in the M&P, they shot accurately.
View attachment 1057578
I did buy some stronger recoil springs for the M&P.

At what distance and what size were your groups?

 

[fxvr5]

Here's an article on a 357 SIG conversion.
https://www.shootingillustrated.com/articles/2019/7/19/converting-guns-to-357-sig-testing-options/

 

[WrongHanded]

Conversion barrels are a great thing!

Own a .40S&W but want a .357Sig? Buy a conversion barrel.

Own a .357Sig and want cheaper practice ammo? Buy a .40S&W barrel. Then you also have the option to use .40S&W defensive ammo if you can't find and .357Sig.

Have a .40 or .357 and want to shoot cheap bulk ammo on a multi-day pistol course? Buy a 9mm conversion barrel, a few 9mm mags, and maybe a lower power recoil spring.

Those extra barrels I have sitting around can be put into the guns in less than 1 minute, and allow me to shoot an entirely different cartridge. That's some great versatility for a minimal financial investment.

 

[kcofohio]

At what distance and what size were your groups?

Approximately 15 yds. and no more than a 2 1/2" area.

 

[bangswitch]

I have a BHP 40 S&W. Will a .357 damage the frame? That's the last thing I want..

I wouldnt convert a Hi-power but its been done. Design is almost 100 years old and never meant for those kind of pressures. You could protect the frame. Use a buffer and increase the hammer spring, adjust the recoil strength. Typical stuff. If you can get a threaded barrel with a compensator that would help but I dont know what is out there for Hi-power these days. Its more about the barrel lockup and timing than it is about frame battering.

The .40S&W version of the BHP uses a heavier cast frame (stronger than the older forged frames) and slide is reinforced, plus it has 3 locking lugs to the 9mm's 2 lugs. No reason it couldn't withstand .357 Sig, but why would you want to swap? You're just trading bullet diameter for bullet velocity, and that's on lighter bullets you don't even see in .40S&W. I don't see the .357 Sig doing anything better than the .40S&W.

1911 can handle 9mm fine. Full power 10mm is another story.

I've got well over 2000 rounds through my bone-stock Ruger SR1911 10mm Auto with no issues at all. I think the 1911 platform is perfect for the caliber.

 

[AustinTX]

Odd that so many people seem to think that peak chamber pressure is the sole determinant of how hard a given round is on a pistol, and that you can just compare the peak pressure numbers across calibers and without taking anything else into account.

 

[WrongHanded]

Odd that so many people seem to think that peak chamber pressure is the sole determinant of how hard a given round is on a pistol, and that you can just compare the peak pressure numbers across calibers and without taking anything else into account.

That's why I posted the recoil comparisons.

 

[kcofohio]

Odd that so many people seem to think that peak chamber pressure is the sole determinant of how hard a given round is on a pistol, and that you can just compare the peak pressure numbers across calibers and without taking anything else into account.

I consider the muzzle energy when reloading. Longshot can take the energy of a 124 gr. XTP up to 562 ft. lb. and 800x can take a 147 gr. XTP up to 566 ft. lb., all while being under 40k psi. But I prefer to stay closer to the 506 ft. lb.

 

[starling]

Odd that so many people seem to think that peak chamber pressure is the sole determinant of how hard a given round is on a pistol, and that you can just compare the peak pressure numbers across calibers and without taking anything else into account.

Its a pretty major factor in terms of lockup wear/damage. Frame and slide battering are not as big of a deal and easier to remedy.... depending on platform.

I've got well over 2000 rounds through my bone-stock Ruger SR1911 10mm Auto with no issues at all. I think the 1911 platform is perfect for the caliber.

Big difference between 10mm target loads and full power 10mm. Not many 10mms can handle full power... which is the whole point IMO. If I desire light 10mm target load performance there is a whole lot more options available with 40s&w (which I am also a fan of). Probably best to stick to light loads in your Ruger. Maybe use some of the various 1911 tricks as well for dealing with hotter loads. You can only do so much though in that design. 1911s are awesome but the heavy construction can be misleading. Something like Cheap plastic feeling Glock 20 can handle full power 10mm all day while the 1911 beats itself to death. A lot of people just want something that says 10mm on it so ..... whatever. There are not a whole lot of pistols out there that can really handle that round well in full power. 1911 really needs a beefed up slide and different locking system in my view. Maybe do a longslide with a sig style lockup and a thicker slide around the ejection port. Maybe a rotating barrel like the Obegon 1911. Or.... just beef up everything like an LAR Grizzly.

 

[bangswitch]

Big difference between 10mm target loads and full power 10mm. Not many 10mms can handle full power... which is the whole point IMO. If I desire light 10mm target load performance there is a whole lot more options available with 40s&w (which I am also a fan of). Probably best to stick to light loads in your Ruger. Maybe use some of the various 1911 tricks as well for dealing with hotter loads. You can only do so much though in that design. 1911s are awesome but the heavy construction can be misleading. Something like Cheap plastic feeling Glock 20 can handle full power 10mm all day while the 1911 beats itself to death.

I wouldn't call 1250 fps 185 grain loads as target loads. If I want to download 10mm, I'd rather shoot .40S&W, and I have two of those to choose from. I shot the same load in the 2nd gen G20 I owned for 25 years and got swelled cases for my trouble because of the unsupported chamber. The recoil shock was much worse in the G20, too, the heavier 1911 frame and grip shape are better for me, and it has a fully supported chamber.

 

[Lennyjoe]

I shot the same load in the 2nd gen G20 I owned for 25 years and got swelled cases for my trouble because of the unsupported chamber.

That’s why some of us full power 10MM G20 gun owners use aftermarket barrels (KKM for me) and heavier recoil springs to get the full capability out of that cartridge.

I’d be really hesitant to shoot my 800X 180 gr XTP loads out of a stock 1911….