Whether the .22 LR or the .25 ACP is the more effective is a matter of debate. The ballistics tables give it to the .22, but the ballistics tables are calibrated on longer barreled pistols that produce more velocity and therefore more energy. When you chronograph the two calibers out of identical short-barrel pistols, the .25 is generally seen to be putting out a little bit more power.
Perspective! And I love my Beretta M9A1-22 .22 LR thus far!
