I was talking to a former Air Force MP just last week who thought the military issued Beretta was a "POS". I've never fired that particular model myself. But the 9mm semi auto I have fired felt "weak" compared to the .45 ACP I'm accustomed to.
For the street/point blank confrontation (atm robbery attempt as example) , a hammerless .357 revolver will also shoot .38 special rounds and can be fired from inside a pocket or purse. All the perp will see is your hand in a pocket and not know your finger is on a trigger. The .38 round has less kick and is more controllable and with a hollowpoint it will go in like a dime and come out like a cash register. Hammerless is key here for obvious reasons. It wont snag on clothing material or anything loose in a purse. 2nd, the gun will never need to be shown which puts the surprise element in your favor.
00 buckshot or a slug will penetrate several layers of drywall. As will a .45, .357 mag or 9 mill. 5.56 will not, because it shoots such a small slug, but you lose stopping power. It's all about tradeoffs.
Ruger offers a .357 mag in a small, hammerless snubbie. I have to wonder what the recoil would be, particularly if you are shooting it out of your pocket or a purse where you don't have a good grip. http://ruger.com/products/lcr/models.html Still, this is the most bang for size you will get. I'd hate to have to shoot it inside a car with no ear protection though.
I was too, but I saw a demo on one of the shooting programs on cable. The bullet fragments. You will get some fragments to penetrate, but they are so small they won't do anything.
Speaking of bullet penetration this CEO has brass balls. <embed src="http://www.ebaumsworld.com/player.swf" allowScriptAccess="always" flashvars="id1=81807900" wmode="opaque" width="567" height="345" allowfullscreen="true" />
For me at least, I have no problems with getting a decent grip from in a pocket but you are definitely right on how uncomfortable it would be on the ears when firing it from inside a vehicle because even outside in the open air, my eardrums can't handle much from a .357. I would think the pocket would control some of the recoil if you had a decent grip, and in a point blank situation, one maybe two shots is probably all you'd get. To be honest, it better be all otherwise the table may get turned on you in a court for going beyond stopping the threat. This brings one more thing to think about with why hammerless is nice because it's double action. In the court system, things may get spun against you if you fired from a single action setting because an attorney may try to show that your elevated adrenalin caused an accidental discharge on the lighter trigger pull. You will want to make sure that it can be proven that it was a conscious decision/action for you to defend yourself due to a threat against yours or your family's lives.
don't know much about guns but a customer on my paper route used to load shot gun shells with rock salt,they won't kill you but will burn like crazy in 100 spots