The question was:

Are BB guns good for defense???

The answer is yes, but only in one specific situation. IF you have a high powered air rifle, it can have the same (or more) ft/lb as a .22 short over a very short distance.

The only way to use a weapon that is underpowered and capable of a single projectile in a defensive situation is VERY CLOSE.

This type of weapon must be used (and has been used) no more than 4 inches from the cranium. The preferred method is jam the barrel into the eye socket of the attacker while pressing the trigger.

If you are foolish enough to use this for defense, a large knife on the end of the barrel would be the most useful addition possible.

In other words, at any distance, a super-soaker filled with chlorine bleach or a high concentration of quality (HOT) chili powder and water would be an improvement.

At least get a crossbow if you are scared of firearms.