When you do that keep in mind that there is NOTHING wrong with the 9mm caliber at all IF you carry with the right ammo and the only right ammo for a 9mm handgun with a barrel shorter than 4" is Federal HST 124gr.
If you're a lady with a concealed carry license, they can be lighter and physically smaller to fit better in a purse.
Same argument can be made for a Smaller guy who needs to pack it under street clothes without being stopped, frisked, and held up for paperwork by every badge on the street.
But they are Far from ideal and I wouldn't trust my life to anything pushing a lightweight 124 grain bullet at Any velocity.
Get that pill moving fast enough to compensate for its light weight and you've got over penetration to deal with. Shoot your attackers And someone behind them with the same shot. No thanks.
Also the Hydrostatic shock to consider.
A .45 cal bullet is going to set up hydrostatic shock waves in living tissue that are All out of proportion to the much smaller waves a 9mm will. Inflict a lot more upset/damage, farther reaching shock wave, to more tissue and organs surrounding the bullet path.
That is a Huge difference in stopping power.
If, God Forbid, some ghoul Forces you to shoot them, you are going to have to answer some very specific questions after the fact.
Saying you intended to kill them is about the Worst possible answer to any of them.
Your Intent, was to stop them from killing or crippling you, or you can very quickly find yourself in a world of legal trouble. If they die as a result of it, that decision was Their's, not yours.
A bigger diameter, heavier, slower bullet is a far more effective stopper than a smaller lighter one no matter how it's constructed to mushroom at higher velocity.
