I have an HP22 and if I were carrying it for defense, it would be loaded with CCI’s; either MiniMags or Stingers. (It would also have the 5” barrel installed.)
As others have pointed out, penetration is a crucial consideration in a small .22LR pistol; second only to functional reliability imo. Shooting with a brother-in-law one time with .22’s at a dump (gotta love Arkansas…
), he was using his ruger 5” or 5-1/2" Mk2, and I had my 4” mk2 and my wife’s beretta 21A. Shooting at an abandoned washing machine from probably 30 feet, the federal 40-grain ‘hi-velocity’ solids from the 4” and 5” guns always penetrated the outer sheet metal of the washer, and nearly half the time also penetrated the heavy steel of the inner washtub. The same ammo from the little beretta never once penetrated even the outer skin. You could literally see them land in the grass after bouncing off the outer sheet-metal layer on the washing machine. It shocked me, but it was consistent; 100% of the time, the rounds from the beretta pocket pistol bounced off, and the rounds (from the same box) from both the four and five inch guns penetrated a minimum of one layer and often two.
The tiny bullet from such a tiny barrel length just has a tiny performance envelope, and really needs as much help as we can give it.