people who have specific loads for protection (whether it be home defense or concealed carry) often times carry hollowpoint ammunition. This isn't necessary in all cases. I've found that shooting a lot of 22LR and 25ACP ammo, regular ball ammo does the job well. These slow and relatively lightweight projectiles don't always expand properly. There are a few conditions to take into consideration. the guns people often times carry for self defense are small, short barreled handguns. The velocity to make a 22 or 25 caliber hollowpoint bullet expand like it should just isn't there most of the time they're fired out of short barrels.
Penetration seems to be a problem with these rounds in general, so i wouldn't want to jeopardize that any further by using a hollowpoint round, which in theory should slow down, expand, and not penetrate. Clothing is another thing to keep in mind. When you're shooting a 36-50 grain projectiles that often times aren't breaking 900 feet per second, you need every bit of penetration you can get. A bad guy wearing a heavy jacket or multiple layers of tough cloth can slow down a bullet considerably which drastically effects the penetration of the projectile. Also, if hollowpoints are used on someone wearing thick clothing, the point itself may become clogged and slow down considerably, not inflicting a desireable wound channel on the assailant.
If you have to shoot someone with a 22 or 25, make damn sure it'll do some dammage by using regular round nose or ball ammo. I'm not worried at all about overpenetration, not in the least. These bullets are likeley to ricochet off of bone such as ribs, not break it or go through it like larger defensive calibers tend to do.
When carrying larger calibers such as 380 and 9mm, I always carry hollowpoints to minimize the chance of going through an assailant and harming innocent people or causing unnecessary dammage to other people's property. This threat of overpenetration just isn't a factor with 22s and 25s.