Can you safely fire .38 Super in a .357 Magnum?

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Micropterus

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Just curious. I was checking the rim/extractor contact on my Ruger GP-100 and decided to see if a .38 Super round would fit. Since it is semi-rimmed, I thought I'd give it try so I could see what I was looking for a bit better. Except for being a wee bit tight, the .38 Super rounds slid in nicely and the extractor easily engages the smaller rim.

I know the bullet diameter is slight smaller (.355 vs .357). And the case is a bit bigger in diameter. But otherwise, any reason (ie. pressure, etc) this would not work?
 
I'm not going to do it, I'm just curious. I've owned a .38 Super for nearly 20 years now and this the the first time I've ever checked to see if it would even chamber in a .357.
 
If you search the board a bit, you'll see that this one comes up fairly often for some reason.

"It fit's" isn't generally a good reason to try it, yet I see people wanting to do siimilar things pretty often.

Can it be done? Yep. Is it safe? I'd say one's life, limb, and/or eyesight is a tough gamble to find out.

Especially when .357 mag ammo is easier to find, and cheaper to shoot.

Daryl
 
It lists the PSI of the .38 Super as higher than the .357. But it lists the CUP of the .38 Super as lower than the .357. I don't understand why. I would think if one were higher, the other would be higher, too. Anyone know the relationship between the two?
 
http://www.chuckhawks.com/pressure_measurement.htm

Hope this helps. I am learning also.

Now suppose you see a pressure given in PSI for some hot new cartridge and want to relate that to the more familiar CUP in order to compare it to another cartridge or load measured by that method. As I mentioned earlier, these pressure measuring methods are not 100% accurate and, primarily for that reason, there does not exist an accepted formula for making this conversion.

I suppose that it would be reasonable to guess that, in general, if a cartridge has a published maximum average pressure in the 50,000 CUP range that the PSI equivalent will be considerably higher, generally in the 60,000 range. If the CUP specification is in the 40 to 45,000 range, there is a reasonable chance that the PSI specification may be nearly the same. And if the CUP number is lower than about 40,000 the PSI equivalent will probably be considerably less. Unfortunately, none of these generalizations are accurate or consistent enough to be meaningful to shooters, reloaders, or anyone else.

For reasons not yet understood there are numerous exceptions for individual cartridges. The measured CUP and PSI readings vary considerably from one cartridge to the next and are not consistently different. Remember that the earlier mentioned standards organizations now publish both CUP and PSI specifications, as determined from actual measurements, for all cartridges.
Click to expand...

BTW, notice that the SAAMI spec. I posted in post #10 are all in PSI for the rounds we are discussing, so this should be apples to apples.
 
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OK, I don't recommend firing any cartridge except in a gun designed and marked for it, with some exceptions, like .38 Special in a .357.

So how about those pressures? The .38 Super +P is rated at 36,500 psi (on my chart) and the .357 at 35,000. I doubt very much that such a relatively small difference is going to cause any guns to explode in a mushroom cloud and wipe out whole cities. For one thing, the .357 proof load is around 45,500 psi, so even 36,500 comes nowhere near the pressures a .357 revolver is designed to withstand.

In fact, the .38 Super will fit in a .38 Special/.357 chamber only by virtue of overlapping tolerances. (Of five revolvers I tried, .38 Super fits in only one.)It was based on the .38 S&W case, which Browning originally used in his experiments. It was made longer but that will not prevent firing it in some of the old .38 S&W breaktops that don't have shoulders in the chambers, or in some old .38 Special revolvers designed for a 17,000 psi round. Those would be the areas of my concern, not firing it in a modern .357 Magnum revolver.

Another reason I would not use .38 Super/.38 ACP in a revolver without moon clips is that the small rim will almost always jump the extractor, hanging up the gun in a reload.

Jim
 
I don't recommend it, but, have done it as an experiment in an old model 28. Not a good practice but good info to know in an emergency.
 
I would guess you could fire a 357mag in a 41 mag but I would NEVER do that anymore than I would fire a 38Super in a 357mag. Are 357mag's so difficult to get in your area?
 
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