Though I don't remember seeing anything about this previously, in the past two days I have happened upon a handful of discussions (weird how stuff like this seems to come in groups) on the wear-and-tear that different cartridges put on pistols (specifically autoloaders). They all go like this: Modern, high pressure cartridges like the .40S&W will wear out a gun faster than "standard" (or "low pressure") cartridges like 9x19 or .45 ACP. Now, I did a little research (SAAMI specs), and while the .45 ACP is indeed a lower pressure round (at 21000 PSI), both the 9x19 and .40S&W have the exact same spec at 35000 PSI. Why then are people calling .40 "high pressure" and, in the same breath, saying that a round that "isn't" "high pressure" (9mm) is a better choice for firearm longevity? Is this some kind of superstition, something that's been repeated enough that it's dogma? I could see the .40 causing more damage than the 9mm over time as a more powerful cartridge (it has a greater case capacity by about 45%, so burns more propellant). This, however, has to do with the energy released upon firing, not with the pressure difference (of which there is none).