This topic has come up before. Startled in the middle of the night and/or under duress, most people are inaccruate, or at least inconsistent, with a pistol. Having a stock to brace against and a longer weapon to work with greatly improves accuracy under stress. In a nutshell, any accurate .22 delivered into a BG is better than a salvo of .40 cal bullets that never hit their mark. And if 25 rounds isn't enough... couple two mags together.

For HD, choose your ammo wisely. Buy something that always works, is accurate, and has some mass to it. Try out the CCI Velocitor .40gr or the Winchester Super-X PowerPoint 40gr.