Question about +P rating

IMO, it is purely a marketing ploy by S&W to get people to buy a gun so light it couldn't possibly handle +P ammo. SAAMI is the organization, of which S&W is a member, that sets standards for ammo. It introduced +P in the mid-1970's at the same time it downgraded the pressure rating for standard ammo. +P is essentially standard pressure .38 Special before the pressure standards were revised. SAAMI has also changed upward the proof pressures for .38 Special and now referrs all testing to +P proof pressures. Gun manufacturers are party to these changes and only stupid ones would design a gun that couldn't handle any pressure commercial ammo that it could properly chamber.

The older 38 Special was loaded to around 1,000 FPS (from actual S&W flyer from 1965) and that is +P now. However, the +Pin an airweight is rather harsh, especially if snub nosed. The types of metals but also the treatments of those metals such as heat treating or manufacturing such as cast versus machined may all result in different strengths. I do have a 36, Colt DS, and Colt Cobra all can shoot +P at various times but not steady.
I have found Wadcutters in 38 Special are very effective at creating a nasty wound. I use them and don't stress my guns or hands needlessly. That is JMO.

You can shoot Plus P in both the 36 and the 637 in limited (key word limited) amounts with probably no problems. It would be easier on the guns and definitely easier on the hand. Practice with standard .38 ammo (if you can even find any nowadays) and at the end of the session run a cylinder or two thru it with Plus P. Load them up with Plus P for carry and your ready to go.

If a gun is rated for +P it should be able to handle a steady diet of it. My wife has a 637 Airweight with an aluminum alloy frame that's rated for +P. It's got some pretty snappy recoil for a .38 even with non +P loads. Especially with the stock grips. It has a lifetime warranty so if I wanted to shoot nothing but +P out of it I would and not worry about it.

bonedaddy said:

You can shoot Plus P in both the 36 and the 637 in limited (key word limited) amounts with probably no problems. It would be easier on the guns and definitely easier on the hand. Practice with standard .38 ammo (if you can even find any nowadays) and at the end of the session run a cylinder or two thru it with Plus P. Load them up with Plus P for carry and your ready to go.

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I don't use +P in my 637 so that's not even an issue. I guess my question was why is it not advisable to shoot +P in the 36 except in limited use. FWIW, the 36 dates to 1968. Your reply is the first time I have heard that limited use of +P also applies to the 637, even though the barrel shows "+P."

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The Plus P rating was invented in 1971, so a gun from 68 could not claim to be plus P rated since that didnt exist yet. The catch is that max pressure for 38 special was reduced by SAMMI, and the Plus P rating was what the old max pressure was before it was lowered. In summery, the new plus p is the same as the older 38 special max pressure

jonesy814 said:

The Plus P rating was invented in 1971, so a gun from 68 could not claim to be plus P rated since that didn't exist yet. The catch is that max pressure for 38 special was reduced by SAMMI, and the Plus P rating was what the old max pressure was before it was lowered. In summery, the new plus p is the same as the older 38 special max pressure

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So, can the higher pressure +P be used in a 36, even on a limited basis, or just treat it like the 637? I guess the easy way to settle this issue is to just use standard .38s in the 36. Why do I have a feeling I'm going around in circles on this? 😣

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Maybe I can make this simple. There is no S&W .38 Special revolver that cannot shoot +P all day every day irrespective of how it is marked. Period.

Well, er, except for the aluminum cylinder guns made in the 1960's.

+P gets you essentially nothing. There isn't that much difference in pressure, and therefor velocity, to worry about it. A .38 is not turned into a .357 mag by using +P ammo.

I would go ahead and shoot + P but my hand and wrist would give out long before the Smith would.

The actual difference between a standard velocity round and +P rated round is literally a few tenths of a grain of powder and generally the bullet profile. Perhaps a few hundred FPS faster.

I don't generally shoot them, and would only use them in self defense loads. They will stress your gun more than standard velocity.

For a fractional cent worth of powder, they charge 2x or more per round. Good marketing, especially during a shortage.

I just want to point out that 5150 originally requested to know if his gun could shoot +P ammo without problem. He didn't ask whether it was a good idea or if it conveyed some magic benefit that pedestrian standard pressure ammo doesn't, or whether it cost too much. Why does this always seem to devolve into a philosophical argument when the simple, accurate answer is "yes, you can shoot +P without damaging your gun?"

Wiregrassguy said:

I just want to point out that 5150 originally requested to know if his gun could shoot +P ammo without problem. He didn't ask whether it was a good idea or if it conveyed some magic benefit that pedestrian standard pressure ammo doesn't, or whether it cost too much. Why does this always seem to devolve into a philosophical argument when the simple, accurate answer is "yes, you can shoot +P without damaging your gun?"

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Almost. My gun is the 637 and is rated (labeled) for +P. But maybe I didn't pose the original question clearly. I was wondering if the newer metallurgy and/or engineering, for lack of better terms, allows the 637 and others like it to shoot the +P, whereas it is not recommended for older guns, at least on a high-volume basis. I'm referring to guns manufactured prior to the introduction of the +P rating, like the older Model 36 I was talking about.

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As mentioned earlier, the original .38 special round had the power level of today's +P, and so was proofed to shoot the higher pressure round. In general (with some specific exceptions in lightweight guns with alloy cylinders) that applies through today's guns.

The lack of marked label of approval is more a legal issue than a physical or metallurgy one. Shoot an older gun with +P and don't expect anyone to come forward to guarantee the gun, or take responsibility for safety of doing it. The standard line would be, if you don't know for sure - don't do it.

There were specific points in time (I think in the 1917-1919 era) where heat treatment metal hardening processes were used to improve the metallurgy and resistance to higher pressure.


I have a very early second change M&P, and in spite of it's likely ability to run +P, I'll never intentionally shoot the higher pressure rounds in it. It is well over 100 years old, after all...

Wiregrassguy: Well said. I was not implying to the OP that it is a written rule somewhere to shoot "limited" amounts of Plus P through either gun. It was just the procedure that I follow. Shoot all the Plus P's you want through that 637. Numerous amounts of Plus P ammo through either gun might cause no major problems whatsoever but they will eventually cause unwanted wear to the guns.

Wiregrassguy said:

Maybe I can make this simple. There is no S&W .38 Special revolver that cannot shoot +P all day every day irrespective of how it is marked. Period.

Well, er, except for the aluminum cylinder guns made in the 1960's.

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This. Exactly.

bonedaddy said:

Wiregrassguy: Well said. I was not implying to the OP that it is a written rule somewhere to shoot "limited" amounts of Plus P through either gun. It was just the procedure that I follow. Shoot all the Plus P's you want through that 637. Numerous amounts of Plus P ammo through either gun might cause no major problems whatsoever but they will eventually cause unwanted wear to the guns.

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I don't shoot +P ammo thru my 637, I was just looking for some clarification on the subject.

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5150 --> Did you get what you wanted?

Wiregrassguy said:

5150 --> Did you get what you wanted?

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I guess so. After sifting thru the replies I at least have a better understanding of the marketing side of the industry and all that SAMMY stuff.

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