No doubt S&W has a special deal with LE where they will repair or replace pistols shot up with +P+ but we citizens don't have the same luxury. (shrug)
Ah, no. The agencies that requested the development of +P+ ammuniton (actually that's not what they asked for, see next paragraph) signed hold harmless agreements with the ammunition companies acknowledging that use of such ammunition would cause excessive wear and could result in damaged weapons, injuries and/or death of their employees. This insulated the ammo companies from liability and the agencies assumed all liability, including the repair bills. Then and only then was the ammunition delivered.
+P+ ammunition was developed originally to allow the use of .38 Spl headstamped ammunition to produce .357 Magnum performance and was intended only for use in revolvers chambered for .357 Magnum. This was done to avoid ACLU hysterics about magnum ammo inflicting cruel and unusual punishment. 9mm +P+ was developed in an effort to get the JHP bullets of the day to expand.
Unless you pressure test your individual rounds, you'll never know the pressures developed (and those results will only be good for that ammo lot), which is the point of S&W saying don't use it. It very well could be that some +P+ is about the same pressure as ammunition produced under CIP (European) pressure standards. On the other hand, the next lot may not be.
Typically, US made 9mm isn't loaded as hot as european ammo, our +P gets close. This isn't necessarily because of pressure limits, but because manufacturers load to a velocity specification, not a pressure limit. Some push the envelope further than others. Much of the production of US ammo companies is based upon a price point rather than performance.
BTW, some +P+ is dangerous, not because of pressures, but because a bullet is being driven at velocities outside it's design envelope. They don't expand, they shred. This can result in insufficient penetration, particularly where intermediate obstacles like limbs of the body are involved. I'd be less concerned about magic bullets, maximum performance and more concerned with bullet placement.
Also, doesn't anyone do a search for previous threads on any topic????????????????????