What is the origin of the misconception that .40 S&W is a high pressure cartridge?

[Echo40]

What is the origin of the misconception that .40 S&W is a high pressure cartridge?

To this very day, folks make comments about .40 S&W being a high pressure cartridge, yet if you look at SAAMI Specs, .40 S&W is actually equal to Standard Pressure 9mm Luger, with both cartridges specified as 35,000psi. In other words, even 9mm Luger is potentially significantly higher pressure that .40 S&W due to 9mm Luger +P loads being 38,500psi. (There is no official +P loading for .40 S&W.)

The persistence of this misconception has endured for so long that I cannot help but wonder where exactly it came from and how it has lasted so long in spite of the fact that all it takes is a simple glance at SAAMI Specifications to see that it isn't accurate.
Was the .40 S&W at one point in time loaded hotter or what? As far as I know, it has always been loaded to 35,000psi in the United States, and it was actually loaded quite a bit lighter in Europe at 32,600psi according to C.I.P. Specifications.

So what precisely is the basis for the enduring misconception that .40 S&W is a high pressure cartridge?

 

[Peak53]

If 35,000 psi isn't a high pressure cartridge, I'm not really sure what would qualify. High pressure doesn't mean it is over SAAMI, just that is high relative to say .38 +P at 18,000 or so.

 

[HKSmith]

.40 S&W SAAMI operating pressures are similar to .357 Magnum, .41 Magnum, and .44 Magnum. If that's not high pressure for handguns, I don't know what is. Of course, there are specialty cartridges for big hunting revolvers with higher pressures (.454 Casull, .460 S&W Magnum, .500 S&W Magnum, etc.), but for real world carry handguns .40 S&W is about as high pressure as it gets.

 

[ImprovedModel56Fan]

You ever checked the SAAMI specs for .45ACP?

 

[Echo40]

If 35,000 psi isn't a high pressure cartridge, I'm not really sure what would qualify. High pressure doesn't mean it is over SAAMI, just that is high relative to say .38 +P at 18,000 or so.

Folks often say it's high pressure in comparisons to 9mm Luger.

Also, compared to most other duty pistol cartridges, it isn't high pressure at all.

• 10mm Auto -- 37,500psi
• 9mm Luger +P -- 38,500psi
• .357 SIG -- 40,000psi
• 5.7x28 FN -- 50,000psi

 

[Dave Lively]

357 Magnum - 35,000
44 Magnum - 36,000
10mm - 37,500
45 ACP - 21, 000

The 9mm is also a high pressure cartridge at 35,000.

What sets the 40 apart is how when loaded with 180 grain bullets there is not much room for the powder and it doesn't take much bullet setback to create an over-pressure condition. Cartridges with longer cases like the 10mm will not see as dramatic of a pressure increase if setback occurs.

I wouldn't worry about shooting factory 180 grain 40 myself but would not shoot reloads unless they were my reloads. And I quit reloading.

 

[Golphin]

Not sure about pressure but it shoots harder or more snap to me for the few times I have shot the round in a semi auto pistol. Hard to compare it to a 357 in a N frame revolver but I like shooting 45 auto in a plastic pistol better.

 

[Dave Lively]

Folks often say it's high pressure in comparisons to 9mm Luger.

I don't hear that very often. I do hear that it has more recoil, is bit louder and is harder on guns than 9mm. The first two are true in my experience. The third might be but I don't know anyone that wore one out. Some people might associate recoil and noise with pressure when bullet diameter, weight and the type of powder used are really to blame.

 

[Rule3]

It is a high pressure round for a handgun as is 9mm compared to 45 acp, 38 special, 380, 32 etc etc.. You data is faulty as you claim people compare it to 9mm but you in a lot of words use the 9mm +P?
Who are these people that say"compared to a 9mm?"

At what threshold or definition of "high pressure) start?

I can load a 38 special to 90% of a 357 Mag load the the same with 40SW to 90% of a 10mm load. So are those not high pressure?

 

[Univibe]

One thing that is overlooked is that there is very little space in the case, with 180 grain bullets.

The 180 grain is a holdover from the 10mm. They kept the bullet, but shortened the case to make the .40. The loading density is already quite high, and any bullet setback due to manufacturing or handloading errors can jack the pressure up dramatically.

 

[SP45]

This is just memories from 30+ years ago. As i recall there was discussion about the pressure curve being very quick in the 40 S&W and the semi auto were unlocking before the pressure had reduced sufficiently. I know that Colt had a very hard time making them work correctly.

 

[Sevens]

Nobody that I have ever heard calls the .40cal high pressure compared to 9mm Luger but it's the definition of high pressure as handgun cartridges go.

Far more bemusing are the litany of discussions you open where you seem so personally offend at anyone's opinion regarding the .40 S&W cartridge.

Here is my complaint for the .40 S&W and I formed this circa 1993 or 1995. Counter this one if you like:

The 10mm existed and the .40 S&W was spawned. The 10mm guns were chambered in .45cal sized frames and used .45cal-sized barrels and chambers that were reduced in size from .452" to .400", this added steel around the chamber and around the bore. A hotter, smaller hole in a larger gun.

The .40 S&W hit the scene exactly opposite. Take a 9mm-sized gun and barrel and open chamber, make it larger and sacrifice the steel. Do the same thing for the bore. Bigger hole, less steel. And now fit that top half to a pistol frame designed wholly for the 9mm cartridge.

That was my complaint, it is mostly a historical complaint these days but still fact-based. I own four .40 S&W chambered pistols and one conversion barrel. I shoot three of them regularly. The four that I shoot are large frame S&W PC 4006 Limited, CZ Tac Sport (gargantuan) and a KKM .40cal barrel in a 10mm Glock 29.

All three that I shoot are more appropriate for .40 S&W than the laundry list of guns that dot the timeline of history which were little more than .40cal parts stuffed in to 9mm guns.

The .40cal is a fine round. Maybe keep in mind that ALL the folks who don't care for it aren't buying up guns you love and components and ammo too, leaving more for you to get. The globe is certainly big enough for everyone to like what they like and avoid what they don't.

 

[ContinentalOp]

FWIW, I don't recall ever seeing the .40S&W described as a high pressure round. I have seen comments that the 180gr load is maxed out on pressure because of the limited case capacity. That was one of the reasons I used 165gr loads back when I had a Gen3 Glock 23. Plus lots of descriptions of heavier/snappier recoil than equivalently-sized 9mm, and even .45ACP, guns. But not really anything regarding pressure.

The .40 S&W hit the scene exactly opposite. Take a 9mm-sized gun and barrel and open chamber, make it larger and sacrifice the steel. Do the same thing for the bore. Bigger hole, less steel. And now fit that top half to a pistol frame designed wholly for the 9mm cartridge.

IIRC, the Sig P229, while based on the P228 9mm, was designed around the .40S&W, hence the heavier, solid stainless steel slide, and I believe some internal frame design changes (maybe?). The P229 was then adapted to 9mm and .357Sig. I've seen comments that the P229 is actually over-engineered for 9mm, but I'm not entirely sure that's a bad thing.

I think the original Glock 22/23 was designed as you described, essentially taking a 9mm gun and chambering it for .40S&W. It wasn't until later that Glock made the design changes (Gen3?) to better accomodate the .40.

Can't say anything about the development of the other .40S&W pistols.

 

[S&WIowegan]

Pressure compared to??

I have been shooting and handloading the 40 S&W cartridge since it became available. My interest was for USPSA-type shooting. The president of USPSA at the time 40S&W came on the market personally chronographed some Winchester 180 gr factory ammo and declared it made major power factor(at the time 175pf required). Many of us chronoed the same ammo and discovered it DID NOT make major pf.

We handloaders went to work to find powder/bullet combinations that would meet USPSA tests. One of the facts we quickly discovered was Winchester brass had rather thin walls just ahead of the rim. We found bulged or actual blowouts of brass in non-ramped barrels.

In contrast, 9mm brass is actually tapered slightly and has thicker wall ahead of the rim.

Over time, we solved these problems with better brass(Starline), different powders and fully-supported barrels. Also, USPSA eventually lowered the required power factor to 165pf.

The raw pressure numbers quoted by the original poster are only useful relative to brass and barrel combinations.

 

[ggibson511960]

Here's my 2 cents. More 40 S&W cartridges are loaded with truncated cone bullets, or hollow points, more prone to hang and scrape on a feeding ramp, pushing the bullet farther into the case and boosting pressure. Same could happen in a 9 mm, but for decades the predominant loading was a FMJ round ball that feeds more reliably without damaging the cartridge in a gun poorly set up to feed. I read an anecdote recently that Allied troops in WW I summarily shot German soldiers found to be carrying truncated cone FMJ ammunition in their Lugers, even though technically allowed by the Geneva Convention provisions against dum-dums and hollow points.

 

[Sevens]

I admit that I know precious little about almost all Sig pistols.

The .40 S&W hit the market in two different guns: the S&W 4006 where the round was developed and the Glock 23 which was rushed to market after a Glock rep stole a few loaded rounds of .40 S&W on display in the S&W booth at a trade show.

The 4006 has a couple of alterations from the 5906 but they aren’t major and my point remains the same — 9mm guns with .40cal shoehorned in to them.

 

[MyDads38]

My first experience with 40 S&W was Feb. 15, 2015, bought my first ever 40 cal handgun-a S&W SD40VE. I have since added 5 more. I don't find it unpleasant to shoot, though it does have slightly more recoil than a similar size 9mm. I normally shoot 165 gr. ammo, but also shoot the 180 gr with no issues-factory and reloads (mine). Too bad S&W doesn't offer the 40 in a 45 size frame.

 

[S&WIowegan]

My first experience with 40 S&W was Feb. 15, 2015, bought my first ever 40 cal handgun-a S&W SD40VE. I have since added 5 more. I don't find it unpleasant to shoot, though it does have slightly more recoil than a similar size 9mm. I normally shoot 165 gr. ammo, but also shoot the 180 gr with no issues-factory and reloads (mine). Too bad S&W doesn't offer the 40 in a 45 size frame.

The 40 S&W was intentionally designed to run in 9mm-sized pistols. Not only was the 10mm cartridge too hot to handle for some FBI agents, the gun was also heavy and bulky. FBI was trying hard to add female agents.

 

[reccpd101]

My first generation 4013 is practically identical in most dimensions to a 4516 so S&W did for a short time build a .40 on a .45 frame. It was my last LE issue gun and awarded to me by the City upon my retirement. At that time, uniformed officers in my agency carried the Beretta 96 and officers who worked plainclothes had a choice between the two. Most opted for the 4013. Any one doing undercover work could carry most anything they could qualify with so as not to have an obvious police gun. In NC, it was/is commonplace for cities to loan or trade officers for undercover assgnments.

At that time, .40 S&W and 3rd Gen S&W autos in all calibers were commonly related to police so most undercover officers in my agency went with Browning Hi-powers and 1911s. We had several in the armory for that purpose. Mostly former evidence seizures awarded to the department by the Court.

 

[typetwelve]

I'm not sure if this has been mentioned or not, but I think that it's because of recoil. It's easy to believe that x caliber has a higher case pressure than y caliber because it produces harder recoil.

Someone mentioned that many 40 semi autos aren't much larger than 9mm semi autos. Ball ammo for ball ammo for ball ammo, 115g 9mm is going to kick much lighter than 165-180g ball with a higher case pressure. Heck, 45 auto with a max case pressure of well under 20K psi has a punch to it, depending on what you're firing it out of.

Of the 40's I've shot (which isn't many), factory ammo is far more snappy than 9mm, but quite a bit. Case in point, my uncle had a SA XD sub compact in 40, I have one in 9mm. After shooting them back to back, we both found the 40 to be much more challenging to control having harder recoil. He traded it in on a 9mm.