The P22 has a cast zinc slide. Doesn't the PK380 have a steel slide with a steel subframe?The manual says it is okay to fire any SAAMI spec ammo, but there is no SAAMI spec for .380 +P. So if you buy something that someone is calling "+P", but there isn't a SAAMI maximum pressure for .380 +P, you aren't buying SAAMI spec ammunition and you are violating the manual.
If SAAMI created a .380 +P spec, then it would be acceptable to fire ammo that meets that spec.
Buffalo Bore ought to call this ammo +P+ since it is loaded beyond any set pressure SAAMI limit. +P always has a pressure limit. I wish +P was copyrighted so SAAMI could tell people not to use it when it isn't correct -
it's false advertising. There are only four +P ammo specs - 9mm +P, .45 ACP +P, .38 Special +P and .38 Super (which is the +P version of .38 ACP). There is no +P spec for .40, .380, .32, .45 Colt, etc.
There are loads that are common and well above any SAAMI spec, like .45 Super, but those loads have their own non-SAAMI definition, and the Walther manuals say to stick to SAAMI. If you call Buffalo Bore as the Walther manual suggests, Buffalo Bore will tell you their .380 +P is not loaded to a SAAMI spec.
Personally, you couldn't pay me to fire overpressure +P+ ammo in a gun with a cast zinc slide (PK380). Don't do it.