If limited to one carry gun...
Would use S&W Model 19, round butt, 2.5" inch barrel.
However, in real life, I carry (and conceal) all the frame sizes.
+P and +P+....
Refer to PEAK pressure generated. Not to total pressure applied to the projectile. Hence, not directly related to bullet performance. Often just marketing hype, but tis a valid warning to use caution in guns of less than full strength.
Sam