S&W revolver marked 'TESTED FOR +P+'

H

Hook686

New member
I bought a used S&W 640 marked .38 Spl on the barrel. Inside the cylinder frame opening of my 640,on the bottom visible when cylinder is opened, is stamped, "TESTED FOR +P+". This is a revolver stamped for .38 Special on the barrel, and +P+ is not a SAAMI standard. .357 magnum rounds do not fit in the chambers. I just got a response back from Smith & Wesson about this and the reply says the revolver CEN 5755 was part of a limited production and that .38 +P would not be a problem in this J-Frame. I am thinking of trying .357 magnum low end reloads in this revolver. Has anyone ever had experience with a S&W revolver stamped, "TESTED FOR +P+" before?
 
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What year of production is the revolver? Sounds like it's a 357 cylinder in a 38 spl frame. Might be interesting item for a letter.
 
Has anyone ever had experience with a S&W revolver stamped, "TESTED FOR +P+" before?
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From what I've read before, the first thousand or so 640s were marked with "TESTED FOR +P+". Lawyers for S&W then informed R&D and manufacturing that since there were no standardized figures for +P+ that the etching had to be removed to prevent litigation.

I can't vouch that it was removed for legal reasons, but S&W did advertise revolvers as being made for +P+ at one point.

I'd take a guess that yours has a serial number prefix of "CEN".

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As you point out, there is no SAAMI standard for +P+ and that is why S&W quit marking the guns that way. As 9x18 says, there is no documentation to back that up, but it makes adequate sense to me.

If somebody transplanted a .357 cylinder to the M640, it would not likely blow up with ".357 low end reloads" but I don't know how long it would take to loosen it up... or crack the receiver ring. I wouldn't push it.
If they reamed out the .38 cylinder, I would not get any magnum load anywhere near it.
Compare it with a 640 Magnum to try to tell which, I THINK the magnum cylinder is longer.
 
9x18_Walther great post. The 640 I bought has a 2-1/8" barrel, but otherwise is as described in that poster. I'll limit my shooting with it to .38+P, and not be concerned with trying anything higher than high end .38+P. CEN 5557 seems to be a 1991 era Model 640.
 
Have put thousands of rounds through my S&W M640 +P+ 38SPL, much of it 38+P+ ammo seconds from the plant. NO PROBLEMS.
The original S&W M640 test gun had exacty 10M rounds run through by S&W. IT ended up as the smoothest J-Frame I ever saw; NICE, and not a hint of undue wear.
At that time there was considerable 38+P+ ammunition in the marketplace IF you knew where to look.
And so it goes...
 
+P+ in 38Spl is particularly problematic, especially if we're dealing with older batches and/or anything marked "police use only".

Back in the '70s and late '80s police didn't want to use "Magnum" ammo as that term had been co-opted by the "Dirty Harry" movies. So some of the ammo houses whipped up basically low-grade 357 in 38 shells marked "+P+" so that cops could testi-lie on the stand that they weren't using "evil magnums". It could still loosen a lot of lesser 38 guns in short order.

We're now seeing the 9mm turned into "+P+" but we have a better understanding of what guns it's safe to use it in: large-frame police duty weapons including the Glock 19 and anything of similar strength. Don't use it in a "pocket 9". Although the Ruger LCR9mm may be able to cope as the cylinder and frame are based on the 357 variant, not the aluminum-framed 38...
 
Not being a wise cracker but, if 357 mag rounds don't fit, how do you intend to load lower end 357 mag loads for this gun? God Bless
 
He is talking about handloading such rounds.

Building ammo like that is extremely easy to do -- standard pressure .357 Magnum runs TWICE the peak pressure of .38 Special. The extra bit of brass/length in a .357 is not at all necessary to build full .357 loads in .38 brass.

Obviously, there are many good reasons to never do this, but anyway...
 
I am thinking of trying .357 magnum low end reloads in this revolver. Has anyone ever had experience with a S&W revolver stamped, "TESTED FOR +P+" before?
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Hook, as you posted .357 Magnum ammo will not fit in the charge holes of the cylinder, so are you going to load up some HOT 38 special rounds? I have a M 640-1 which is factory chambered for the .357 Magnum cartridge, and it is NOT fun to shoot with .357 Magnum ammo. In fact it's not a lot of fun to shoot with HOT 38 special ammo, such as the Underwood 158Gr +P 38 special rounds.

Finally I see no reason to abuse you revolver or yourself shooting more than a LIMITED number of ultra hot ammo in it.

Best of luck with whatever you decide.
 
From what I've read before, the first thousand or so 640s were marked with "TESTED FOR +P+". Lawyers for S&W then informed R&D and manufacturing that since there were no standardized figures for +P+ that the etching had to be removed to prevent litigation.

I can't vouch that it was removed for legal reasons, but S&W did advertise revolvers as being made for +P+ at one point.
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"the first thousand or so" rumor is not true. The CEN 77XX serial range 640 i own has the "TESTED FOR +P+" mark.

S&W introduced the 640 in their 1990 catalog, and even claimed that it was RATED for +P+ ammo.

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WVMountaineer wrote:

Not being a wise cracker but, if 357 mag rounds don't fit, how do you intend to load lower end 357 mag loads for this gun? God Bless
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Reload ... 6 grains of Power Pistol with a 158 grain Speer LSWC .... about 1040 fps per Alliant web site for .38+P,

Vs.

6 grains of Unique with a 158 grain Speer LSWC ... about 1035 fps per Alliant web site for .357 magnum.

This strikes me as a lower end of the .357 magnum range. 6.6 grains of Hodgdon's CFE Pistol powder will yield on the order of 1320 fps with a 158 grain LSWC, which might be at the upper end. 300 fps is nothing to sneeze about in my book.
 
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Old Bear wrote:

Hook, as you posted .357 Magnum ammo will not fit in the charge holes of the cylinder, so are you going to load up some HOT 38 special rounds? I have a M 640-1 which is factory chambered for the .357 Magnum cartridge, and it is NOT fun to shoot with .357 Magnum ammo. In fact it's not a lot of fun to shoot with HOT 38 special ammo, such as the Underwood 158Gr +P 38 special rounds.
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True. I loaded some 158 grain LSWC using 5.2 grains of Unique and got 990 fps. This is about the the maximum I care to shoot with either the 640, or the M&P 340. For practice I load the 158 grain LSWC with 4.5 grains of Unique and get about 850 fps. Still a kick, but more manageable and can shoot most of the afternoon with.

I will be looking for a .38+P 158 grain commercial load that yields about 950 - 1000 fps for carry purposes, as I seriously doubt that pin point target accuracy is required at 'Bad breath' distances.
 
I believe the most obnoxious revolver I ever shot was a 2.5" M66 S&W with 158 gr. Copper-washed ("Lubaloy"?) SWC. Worse than a 4" Model 29 with magnum loads. The 3" SP-101s didn't bother me that much. I can't imagine that 1/2" more barrel made all of the difference, but it must have contributed at least some, I'd expect to find that +P+ 640 somewhere between the M66 and the SP-101.
 
I just got a response back from Smith & Wesson about this and the reply says the revolver CEN 5755 was part of a limited production and that .38 +P would not be a problem in this J-Frame. I am thinking of trying .357 magnum low end reloads in this revolver. Has anyone ever had experience with a S&W revolver stamped, "TESTED FOR +P+" before?
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Hook, I again read your first post. You stated your revolver was marked +P+, but the response from Smith and Wesson, advised you that .38 +P would not be a problem in this J-Frame. So my question is, is your revolver factory marked for +P+ ammo, for which there is NO SAMMI spec, or is your revolver marked really marked +P+? If so I believe this was a case of a factory miss-stamp, which happens every now and then.

Sir, I'm sure you know this but there is a huge power and pressure difference between .38 special even +P and .357 Magnum ammo. So please be careful with what you load up.
 
Hook, I again read your first post. You stated your revolver was marked +P+, but the response from Smith and Wesson, advised you that .38 +P would not be a problem in this J-Frame. So my question is, is your revolver factory marked for +P+ ammo, for which there is NO SAMMI spec, or is your revolver marked really marked +P+? If so I believe this was a case of a factory miss-stamp, which happens every now and then.
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It's no miss-stamp (other than to S&W's liability lawyers)...

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540mope, just about the time you think you've seen it all, something like this comes along. I'd be willing to bet a cold beverage, that if any owners of revolvers that were factory marked such as the one in your photo called Smith and Wesson about this, they (Smith and Wesson) would be more than willing to exchange the revolvers in question for just about any other they make.

I still don't understand how you can certify a product to be safe with out a set standard. It looks like someone at S&W dropped the ball on this one.

Did a little checking at the S&W forum. Smith and Wesson did produce a limited run of these revolvers, that were pressure tested for the "Treasury 110Gr. 38 special load." These were very hot 38 special loads. Most serial numbers started with CEJ.
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It appears that these were fairly early M-640's, about 5,000 were produced. So not as limited as I thought, and I've lost my bet:eek:. Doc, when we get up you can claim the prize:D.
 
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