[EZ CZ75]

I have spent a few days now looking for info on why the 38 has to have lower pressures than the 357 mag. I have not found any direct answer, although I am sure it is out there.

So, why can't one putas much pressure in the 38 considering it is only 1/8" shorter than the big brother?

From what I have read it seems that it might be from webbing, case structure, tolerances, gun metalurgy, etc...

IOW, I have found a lot that might contribute to it, but nothing so far that is concrete. Is it something along the lines of S&W Vs. Ruger where only Rugers should be used for the hottest loads?

I have found references to the 38 being loaded hotter back in the 60's and 70's, almost to 357 mag velocities, but I have not seen any actual data myself.

Thanks in advance for the help.

[Ben Shepherd]

The difference:
357 is currently loaded to 36,000 psi.
Hot 38 stuff is around 21,000.

The 38 brass itself can generally take the higher 357 pressure, but the firearm it's chambered in can't.

[Vern Humphrey]

The .38 Special was orginally developed as a black powder round. Revolvers chambered for that round were never designed to handle the pressure of the .357. Even after the transition to smokeless powder, ammunition companies had to remember their ammunition would be fired in revolvers designed for black powder.

Conversely, revolver makers, knowing the pressures developed by the ammuniton, designed revolvers to be safe at the pressure level, but not at higher levels.

The first .357s were not .38 specials at all -- Smith and Wesson used the .44 caliber Hand Ejector for their .38-44 and Registered Magnum revolvers, while Colt used the SAA and New Service. Both of those were designed for the .45 Colt. Later Colt offered the Official Police frame -- which was originally designed for the .41 Colt in .357.

[model 649]

Wot he said, plus, the .357 was developed from the .38 special cartridge, used in custom guns with beefier components to take the pounding. The length difference in the modern .357 cartridge is to keep it from chambering in a .38 special gun. Same principal with .44 special and .44 magnum. So, technically, yes, you could load a .38 special to .357 pressures. firing it would require a custom .38 gun, however.
Josh

[Archie]

... is the .38 Special dates from 1898 or so and was typical of the day. Loaded to black powder pressure and velocity (and often loaded with black powder) the guns were designed for that pressure range (about 15000-16000 if I recall correctly. 20000-21000 is the +P level.)

The ammunition makers liability factors drive them to load for the weakest link, so to speak. .38 Special revolvers have strengthened over time, but the change has been incremental. WWI revolvers were stronger than 1898 revolvers. WWII revolvers stronger than WWI. 'Modern' revolvers are probably stronger yet. Still, no one (gun makers, ammo makers, this website or me) would encourage anyone to purposely overload a revolver on the basis it will 'probably' handle the pressure.

[ugaarguy]

So, why can't one putas much pressure in the 38 considering it is only 1/8" shorter than the big brother?

Theoretically you could in a gun chambered for 357 Mag. since it will hande the pressure, but DO NOT DO IT; the risk of mixing up the ammo and possibly running a 357 mag level cartridge thru a 38 special is not worth it. The 357 Magnum came about from Elmer Keith hot loading the 38 special in guns strong enough to handle it. S&W wanted to make it commercially available, but even in the fisrt half of the 20th Century liability was a major concern. S&W didn't want to deal with someone putting it in a 38 that wasn't strong enough to handle it, especially with th ease of identical looking rounds getting mixed up. So, they lengthened the case slightly to keep someone from chambering it any 38, gave it a new name, and the 357 Magnum was born. As Ben Shepherd said, the pressures are significantly higher in a 357 Magnum and therefor the gun frames and cylinders undergo a much more refined heat treatment to handle it. Elmer Keith's loading the 44 special to the extreme was also the genesis of the 44 Magnum.

[EZ CZ75]

That, my friends, was exactly what I was looking for.

Just to put everyone at ease, I have hand loaded for almost 15 years and had no plans to try loading the 38 too hot. After all, the only 38 we own (it is my wife's because it is cute) is a snubby stainless S&W. Fun gun, but there is no sense in just wasting powder in a short barrel.

Thanks again for the help and info.

[Gary A]

Ben Shepherd wrote: "Hot 38 stuff is around 21,000", and Archie wrote: "20000-21000 is the +P level". I have spoken to Speer and they confirm their 135 grain Gold Dot short barrel +P load is loaded to around 20-21000 psi. What confuses me a bit is that I have always read that SAAMI standard for 38 Special +P was 18,500 psi versus 17,000 psi for standard pressure. Has that changed? I ask because many people say that +P is OK for limited use in older alloy frame revolvers because it is not loaded much hotter than standard stuff. Going from 17,000 psi to 18,500 psi, I can see their argument, but going from 17,000 psi to 21,000 psi is a horse of a different color, isn't it? By the old standard, 21,000 would be +P+. Help me out here. What am I missing?

[Onmilo]

Gary if this helps your quandry, I have never advocated the use of any +P cartridge in any alloy frame revolver.

[Steve C]

Special +P was 18,500 psi versus 17,000 psi for standard pressure. Has that changed?

What has changed is the units of measurement for cartridge pressures in the last 10 years or so. Many people fail to note that the old pressure measuremnts where CUP (copper units of pressure) and the current pressure measurement is in PSI (lbs per sq inch).

There is no direct conversion formula between CUP and PSI as CUP isn't a mathmatical scale. The OLD CUP standard for +P .38 spl was 22,200 CUP and the standard load was 18,900 CUP.

The modern PSI equivalents to the old CUP maximum pressure for the .38 spl is 18,500PSI for +P and 17,000 PSI for standard loads.

[Gary A]

Onmilo wrote, "Gary if this helps your quandry, I have never advocated the use of any +P cartridge in any alloy frame revolver."
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I tend to agree with you and that is how I treat mine. However, I keep looking at these questions to see if my thinking is accurate or too conservative. I really like the Speer loads (for steel frame guns) but know they are really on the high-pressure side. I note that in their technical paper on the 135 .38 Special, they use a steel 640 for testing.


Steve C wrote, "The modern PSI equivalents to the old CUP maximum pressure for the .38 spl is 18,500PSI for +P and 17,000 PSI for standard loads."
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And that is my point. I have always considered the maximum psi pressure for .38 Special plus P to be 18,500 psi. That is why Speer's answer to me that the 135 load runs somewhere between 20,000 and 21,500 psi (the tech paper says MAP is 21,500, an e-mail quoted a tad less) is so perplexing. I know people are at least loading these in older airweights. That might be fine but for actual shooting, I think they are too hot for alloy revolvers, especially older ones. A lot of people claim plus P is only a little more pressure than standard. Maybe so, but 17,000 to 21,500 is a jump of just under 26.5 percent. More than a little in my book.

I appreciate the feedback.

[unspellable]

There are two different points to consider when running hot loads in a revolver. It's excessive pressure that will cause catastrophic failure by blowing a gun apart. But excessive recoil makes a gun shoot loose. It's the latter that argues against level II 45 Colt loads in a S&W, not the pressure.

On the other hand, it should be remembered that guns are proofed for a reason. A gun might have enough metal in it to take a super hot load, but it also might have a flaw that held together for the proof load but will let go with a hot rod load.

[Jim Watson]

I have shot enough .38 +P in my Airweight S&Ws to know where it hits and how it feels. My neck is worth more than some extra wear and tear on a replaceable gun. I practice with standard stuff so as to not beat them into unreliability.